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Postdates Pregnancy
CHAPTER 53
Postdates Pregnancy D. Jill Mallory, MD
PATHOPHYSIOLOGY
INTEGRATIVE THERAPY
Postdates or postterm pregnancy is defined as a pregnancy that extends to or beyond 42 weeks of gestation (294 days or estimated date of delivery [EDD] plus 14 days). A normal pregnancy lasts approximately 40 weeks from the start of a woman’s last menstrual period, but any pregnancy that lasts between 37 and 42 weeks is considered normal. Approximately 4%–7% of all singleton pregnancies extend to 42 weeks or 14 days beyond the EDD.1 Postterm pregnancy is associated with a higher perinatal mortality rate (stillbirth and newborn death within the first week) and a higher risk for complications during delivery, such as an emergency cesarean delivery, shoulder dystocia, postpartum hemorrhage, birth asphyxia, meconium aspiration syndrome, and neonatal birth injury.2 Current research suggests that the lowest infant mortality rate is achieved when pregnant women have completed at least 41 weeks of gestation before labor is induced and when induction occurs before or at 42 weeks of gestation, although the absolute risk for problems from delivering beyond 42 weeks is low.2 The overall risk for perinatal death is estimated at 0.4% in women who deliver beyond 42 weeks of gestation and 0.3% for women who deliver between 37 and 42 weeks of gestation.3 Because of this small increase in perinatal mortality, the induction of labor is widely practiced at or before 42 weeks of gestation, and postterm pregnancy has become the most common reason for induction.4 Unfortunately, labor induction itself is not without risks. Obstetric problems associated with induction of labor in postterm pregnancy include cesarean section, prolonged labor, postpartum hemorrhage, and traumatic birth. These problems are more likely to result from induction when the uterus and cervix are not ready for labor.2 Furthermore, induction of labor brings with it increased risks of uterine rupture, uterine hyperstimulation, fetal distress, and instrumentation.5 Very few studies have considered women’s experiences and opinions when it comes to the timing of inducing labor, and for women seeking a natural, unmedicated labor and birth, induction poses many philosophical challenges. Accurate dating is obviously important for reducing the need of induction, and studies have shown that early ultrasound is associated with a reduced incidence of pregnancies misclassified as postterm.6 When women have accurate pregnancy dating and are approaching 41 weeks of gestation, many may seek nonpharmaceutical measures of cervical ripening and labor induction. One small study of 50 women showed that many were opposed to medical induction of labor, yet they used self-help measures to stimulate labor at home.7 More research is needed in the realm of nonpharmaceutical cervical ripening and labor induction options for women who have postdate pregnancies.
Nutrition Pineapple Pineapple (Ananas comosus), which contains the compound bromelain, has historical medicinal use both as a whole food and in extract form. Bromelain has been proposed as the active ingredient, and it is present only in the fresh fruit because the canning process destroys it. Bromelain has been used to elicit uterine contractions as a means of shortening labor. Some animal model research suggests that instead of increasing cervical prostaglandins, bromelain may actually inhibit them.8 No research is available on the possible effectiveness of bromelain for induction of human uterine contractions, although this use is widely suggested in lay pregnancy resources. Some investigators suggest that pineapple’s effects on labor may result from gastrointestinal stimulation by fiber and sugar, thus affecting local neural pathways.9 No known risks are associated with pineapple use in pregnancy.
Supplements Castor Oil Castor oil, derived from the bean of the castor plant (Ricinus communis), has a very rich history of use for labor stimulation that dates back to ancient Egypt. One survey completed in 1999 found that 93% of U.S. midwives reported using castor oil to induce labor.10 Despite this prevalence, research into the use of castor oil has been limited. A recent study in mice found that the castor oil metabolite ricinoleic acid activated intestinal and uterine smooth muscle cells via prostaglandin E2 receptor 3 (EP3) prostanoid receptors.11 This may explain its mechanism of action in humans. Three trials were included in a recent Cochrane review looking at castor oil for labor induction.12 It included 233 women at term and compared ingestion of castor oil with no treatment/ placebo. Outcomes evaluated included cesarean section rate, meconium staining of amniotic fluid, instrumental delivery, and Apgar scores. All women who ingested castor oil had nausea; otherwise, outcomes were not significantly different from those in women who did not ingest castor oil. A retrospective observational study done in Thailand of 612 women looked at the timing of delivery, fetal distress, meconium-stained amniotic fluid, tachysystole of the uterus, uterine rupture, abnormal maternal blood pressure during labor, Apgar scores, neonatal resuscitation, stillbirth, postpartum hemorrhage, severe diarrhea, and maternal death.13 No differences were seen 535
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in outcomes between the women who ingested castor oil and the women who did not. This finding suggests that castor oil is safe to use but may not be helpful. Prospective randomized controlled trials are needed. Evening Primrose Oil Evening primrose oil (Oenothera biennis) is often used for several health conditions of women, including breast pain (mastalgia), menopausal and premenstrual symptoms, and labor induction or augmentation. It contains the amino acid tryptophan and an unusually high content of essential fatty acids, especially cis-linoleic acid (CLA) and gamma-linoleic acid (GLA).10 These fatty acids are prostaglandin precursors, which may explain traditional use of the oil for stimulating cervical ripening.10 This supplement is used widely during the last month of pregnancy by midwives in the United States both for cervical ripening and to decrease the incidence of postdates pregnancy.10 Evening primrose oil is traditionally administered as one to two capsules intravaginally at bedtime, starting after 37 completed weeks of pregnancy. There has been one case report of an infant born with petechiae and ecchymosis after its mother took primrose oil a week before giving birth.14 One study investigated oral administration and showed that this route was not effective.15 Furthermore, the oral use of evening primrose oil during pregnancy may also be associated with more prolonged labor and an increased risk for premature rupture of membranes, arrest of descent, oxytocin use, and vacuum extraction.15 This finding is not surprising because oral administration during pregnancy was never a traditional use. Larger trials assessing the efficacy of vaginal administration are needed.
Homeopathy Homeopathy is a safe choice for pregnant women and babies because the remedies used in this system of healing have no pharmacological action.16 In the United States, the use of homeopathic remedies has increased, and a survey among nurse-midwives in North Carolina reported that 30% recommend homeopathic substances for use during pregnancy. The two most common homeopathic remedies used for labor induction are cimicifuga (homeopathic black cohosh) and caulophyllum (homeopathic blue cohosh), which are believed to act directly on the uterus and cervix. These remedies have a long history of use around the world for labor stimulation, especially in Europe and India.17 Caulophyllum is used either to induce labor or augment labor if uterine contractions are short and irregular or when uterine contractions stop. Caulophyllum and cimicifuga are both indicated for dysfunctional uterine contractions and are thought to help initiate a coordinated and effective contraction pattern. Cimicifuga is used specifically to ease the fear of labor and delivery in women who have a history of traumatic childbirth, miscarriage, or abortion.18 Cimicifuga alone is administered as a single dose of 30 C or 200 C potency every 30 minutes for at least 2 hours or together with
caulophyllum 200 C, alternating doses of the two remedies for a total of six doses in 24 hours. Other remedies that are commonly used for labor induction include aconite, arsenicum, gelsemium, phosphorus, and pulsatilla. These are all given in 200 C potency as a single dose (two pellets).19 A 2003 Cochrane review examined the use of caulophyllum, cimicifuga, and some of these other homeopathic remedies.16 The review assessed only two studies comparing homeopathy and placebo for cervical ripening or labor induction and found that small sample sizes and insufficient detail in the research made it impossible to draw any meaningful clinical conclusions. More research needs to be conducted to determine whether homeopathy is a potentially viable alternative to oxytocin and prostaglandins for labor induction. Furthermore, studies should be designed to incorporate individualized homeopathic treatments, prescribed by a trained homeopath, to account for the individualized nature of this modality.
For labor induction, caulophyllum and cimicifuga homeopathic remedies are as follows: 30 C or 200 C given every 30 minutes,1 pellet of each remedy, for a total of six doses in 24 hours. No remedy is given the next day. Repeat the same protocol on day 3 if needed. Other remedies to consider are gelsemium for fear of birth and pulsatilla when contractions come and go, but labor never becomes established.
Botanicals Red Raspberry Leaf Red raspberry leaf (Rubus idaeus, Rubus occidentalis) has been used as a uterine tonic and general pregnancy tea for at least two centuries. Although this botanical is often mistakenly recommended to induce labor, its actual role is to increase blood flow to the uterus and aid the uterine muscle fibers in more organized contraction. Studies indicate that some of the plant components, such as fragrine, an alkaloid, do act directly on smooth muscle.20 Animal studies show conflicting data in terms of the herb’s effect on uterine muscle. Some studies show a contractile effect, whereas others show a relaxing effect. Historical uses include prevention of miscarriage, prevention of postdates pregnancy, decrease of discomfort in prodromal labor, and decrease of morning sickness. Red raspberry leaf was also probably consumed for nutritional support because the plant contains many nutrients, including vitamins A, C, and E, as well as calcium, iron, and potassium. Overall, the herb does seem to reduce the risk for postdates pregnancy and appears safe for general use.21 One randomized controlled trial of 192 women showed no adverse effects to mother or baby, a shorter second stage of labor (a mean difference of 10 minutes), and a lower rate of forceps use.19 One retrospective, observational study of more than 150 women also found that red raspberry leaf reduced the risk for postdates pregnancy, but more conclusive data are needed.16
53 Postdates Pregnancy Dosage It is most commonly consumed as a tea, taken as 1–3 cups daily. Precautions Generally regarded as safe
Black Cohosh This herb (Actaea racemosa) also has a long history of use. Native Americans mixed it with chamomile, ginger, and raspberry tea to induce menses and labor. The active compounds in black cohosh include terpene glycoside fractions, such as actein and cimifugoside, which have been associated with an estrogenic effect and are thought to reduce levels of pituitary luteinizing hormone, thus decreasing ovarian production of progesterone.18 This effect may contribute to the initiation of uterine contractions because the relaxing effect of the high levels of progesterone on the uterine muscle decreases before the initiation of labor. However, a systematic review on the use of black cohosh in labor found no evidence of efficacy.22 One of its alkaloids, caulosaponin, causes coronary blood vessel constriction and direct myocardial toxicity in a dose-dependent manner. This poses challenges to practitioners because the doses present in over-the-counter products may be difficult to verify. At least one case report has been published of toxicity in an infant whose mother was given an unknown dose of black cohosh at term.23 At this time, the German Commission E, an expert committee established by the German Ministry of Health that evaluates herbal products, does not recommend the use of black cohosh in pregnancy.24 Blue Cohosh The herb blue cohosh (Caulophyllum thalictroides) also has a long tradition of use as a uterine tonic. It was traditionally used by Native Americans during 2–3 weeks before the onset of labor.22 Between 1882 and 1905, blue cohosh was listed in the United States Pharmacopoeia for labor induction.22 Over-the-counter preparations of blue cohosh contain varying amounts of triterpene glycosides, which have documented oxytocic effects.25 No studies are available on efficacy. Three case reports are available that demonstrate possible adverse neonatal effects, such as fetal hypoxia, myocardial infarction, and congestive cardiac failure.26 Whether these effects resulted from the herb itself is not known, given that herbs are often used in combination with other plants, and adulteration and contamination problems can occur. Until further research on this plant is done, it is best avoided for labor induction.
At this time, the use of blue and black cohosh is best avoided in pregnant women because of safety concerns.
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Biomechanical Therapy Breast Stimulation Breast stimulation has historically been used to induce or augment labor since as early as the eighteenth century.27 Stimulation of the breast is thought to increase the production of endogenous oxytocin in pregnant and nonpregnant women. The most commonly used protocol for breast stimulation involves using either a manual or electric breast pump, manual massage around the areola of the nipple, or rolling the base of the nipple. Typical hospital protocols recommend stimulating each breast individually for 10 minutes each, with a 10-minute rest period following, for a total of four cycles. The Cochrane Collaboration performed a systematic review of six trials with a total of 719 participants that compared breast stimulation with no intervention to induce labor in women at term.28 The review found that compared with no intervention, breast stimulation significantly reduced the number of women who had not gone into labor at 72 hours.28 This difference was not significant in women with an unfavorable cervix. Breast stimulation also reduced the risk for postpartum hemorrhage by 84%.28 It did not seem to have an effect on cesarean section rates. No incidences of uterine hyperstimulation were noted. Breast stimulation for labor induction allows women’s participation in the induction process and has the advantage of being a low-cost and nonpharmaceutical means of labor induction. Observational studies, however, have shown a link between bilateral breast stimulation and uterine hyperstimulation.29 For this reason, unilateral stimulation is typically recommended. Concerns have been raised regarding possible adverse effects on placental perfusion; however, the incidences of abnormal fetal heart rate tracings are similar to those found with oxytocin use.30 Continuous electronic fetal monitoring is typically used with breast stimulation in the hospital setting. A common protocol used by women in their homes at term is unilateral breast stimulation done for 1 hour per day for 3 consecutive days. Until safety issues have been more thoroughly evaluated, this technique should not be used in high-risk populations. Shiatsu Shiatsu is an ancient form of massage based on Chinese acupuncture theory that often includes the use of breathing and stretching. Shiatsu can be done through the clothes or on bare skin and uses static pressure, which can vary from light holding to deep physical pressure applied with the palm of the hand or thumb. Shiatsu lends itself well to maternity settings because specific shiatsu techniques can be taught to birth partners or practitioners. It has historically been used in midwifery practices to induce or augment labor.31 One small pilot study evaluated shiatsu for induction and augmentation of postterm labor.32 Sixty-six women with postterm pregnancies were studied in a hospital-based midwifery practice. Pregnant women
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were taught to massage three acupuncture points in conjunction with breathing techniques and exercises. The controls attended the same clinic, but they were not taught the techniques. The investigators found that the women with postterm pregnancies who used shiatsu were significantly more likely to have spontaneous labor than were the study participants who did not use shiatsu.
Bioenergetics Acupuncture As part of the ancient system of medicine, known as traditional Chinese medicine, acupuncture has been used in pregnancy for thousands of years. Modern studies have evaluated the insertion of fine needles into specific points on the body, as well as the use of mild electrical currents through these needles, known as electroacupuncture. A 2013 Cochrane Systematic Review evaluated acupuncture for inducing labor.33 The investigators identified 14 trials that included 2220 women for review. Acupuncture was compared with sham acupuncture or usual cases. Most of the trials were undertaken in Western countries. No trial reported on the achievement of vaginal delivery in 24 hours or uterine hyperstimulation. The use of acupuncture did not seem to affect cesarean section rates or neonatal seizure rates. Acupuncture did seem to increase cervical ripening; however, it did not seem to shorten labor. There were no other statistically significant differences between the groups, including no differences in neonatal morbidity or maternal mortality. Overall, the limited studies to date suggest that acupuncture appears safe for inducing labor, has no known adverse effects on the fetus, and may be effective. The inherent difficulties in blinding for acupuncture treatment make the study of this technique challenging. Given its safety profile, it may be worth trying in patients who wish to avoid pharmaceutical induction of labor. Table 53.1 provides acupuncture points that patients can massage at home to stimulate labor.
Lifestyle Sexual Intercourse Unprotected sexual intercourse is thought to encourage the onset of labor by two means. One is the release
TABLE 53.1 Acupressure Points for Induction of Labor 1. Midway along the top of the trapezius muscles, if you were to draw a line from the acromion to C7 2. The motion sickness point at the angle between the first and second metacarpals 3. In the semicircle around the distal medial and lateral malleoli 4. The little toe, all over Massage these points for at least 2–3 minutes each. From Mallory J. Integrative care of the mother-infant dyad. Prim Care. 2010;37:149–163.
of endogenous oxytocin in the mother, and the other is cervical ripening caused by seminal prostaglandins. A Cochrane review looked at an observational study of 28 women at term. Unprotected intercourse for three consecutive nights neither significantly changed Bishop scores (1.0 with coitus vs. 0.5 controls; P > .05) nor increased the number of women who went into labor at the end of 3 days (relative risk, 0.99; 95% confidence interval, 0.45–2.20).34 Sexual intercourse in pregnancy is considered safe, provided the absence of placenta previa, rupture of membranes, or active genital infection.30 Larger studies are needed to determine whether sexual intercourse has any significant effect on reducing the risk for postdates pregnancy.
Pharmaceuticals Misoprostol Misoprostol is a prostaglandin E1 analog widely used for off-label indications such as induction of labor in postdates pregnancy. This hormone is given by insertion through the vagina or rectum or by mouth to ripen the cervix and elicit uterine contractions. A Cochrane review looked at 121 trials and found that small doses (25 mcg every 4 hours) of misoprostol vaginally were as effective as other methods of labor induction.35 Larger doses of misoprostol were found to be more effective than prostaglandins for labor induction, and larger doses also reduced the need for additional oxytocin. Another Cochrane review found that the oral route of administration may be preferable to the vaginal route.36 Compared with the vaginal route, oral route of administration was associated with a lower rate of babies born with low Apgar scores and a lower rate of postpartum hemorrhage but with a higher rate of meconium-stained amniotic fluid. A third Cochrane review has looked at buccal or sublingual administration.37 Data on these routes of administration are more limited; however, there was a trend toward a lower cesarean section rate, a reduced need for oxytocin augmentation, and an increased rate of vaginal delivery in 24 hours. More studies are needed to establish the optimal buccal/sublingual dosage. The main risk for misoprostol use is hyperstimulation of the uterus, and this risk seems to increase with increasing dose. At this time, misoprostol is not approved by the Food and Drug Administration (FDA) for induction of labor.
Dosage The most common dose used in the United States is 25 mcg intravaginally every 4 hours (maximum, 50 mcg). Wait for more than 4 hours after the last dose before adding oxytocin. The most common oral dose used is 50 mcg. Misoprostol comes in 100- and 200-mcg tablet formulations. Precautions Uterine hyperstimulation, uterine rupture, diarrhea, nausea, vomiting, headache Although misoprostol is commonly used for labor induction in the United States, it has not been approved by the FDA for this use.
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Oxytocin
Amniotomy
Oxytocin is the most common induction agent used worldwide. It is used alone, in combination with amniotomy, or following cervical ripening with other pharmacological or nonpharmacological methods. Oxytocin is a synthetic analog of the natural labor hormone by the same name. It binds to oxytocin receptors in the uterine myometrium, increases intracellular calcium, and stimulates uterine contractions. A Cochrane review of more than 61 studies concluded that it is safe and effective.38 A black box warning placed on the drug by the FDA states that oxytocin is not to be used for elective labor induction.
The deliberate rupture of membranes may be sufficient to bring about labor without the use of pharmaceuticals. This approach has the advantage of being cheap, but it may be uncomfortable for some women. If the time between amniotomy and delivery of the baby is long, infection may occur. The risk for umbilical cord prolapse is also increased, especially if the fetal head is ballotable at the time of membrane rupture. Anecdotal reports note that amniotomy may be less beneficial in nulliparous women. More evidence is needed regarding effectiveness compared with placebo or compared with other methods of induction of labor.40
Dosage Start with 0.5–2 milliunits/minute and increase by 1–2 milliunits/minute every 15–40 minutes until the uterine contraction pattern is established. The maximum for induction is 40 milliunits/minute. Oxytocin is available in intravenous and intramuscular preparations. Precautions Increased use of epidural anesthesia, uterine hyperstimulation, uterine rupture, abruptio placentae, fetal distress, nausea, vomiting
Vaginal Prostaglandins (PGE2 and PGF2alpha) Prostaglandins have been used for the induction of labor since the 1960s. These drugs are synthetic analogs of the body’s naturally occurring prostaglandins, which function to ripen the cervix and bring about contractions. A Cochrane review looked at 70 randomized controlled studies of various forms of prostaglandins and found them to be a safe and effective means of labor induction.39 Prostaglandin E2 is the most commonly used type, and it increases the likelihood of vaginal birth in 24 hours and may reduce the risk for cesarean section by 10%.39
Membrane Sweeping Sweeping of the membranes, also known as membrane stripping, is a simple manual technique usually done in the outpatient setting. The technique involves inserting a finger into the cervical os during a sterile vaginal examination and sweeping the finger in a circular motion to detach the membranes from the lower uterine segment. This method sometimes works to initiate labor by increasing the local production of prostaglandins. A Cochrane review of 72 studies found that sweeping of the membranes performed routinely for women at term was associated with a reduced frequency of pregnancy extending beyond 41 weeks.41 This method is considered safe and reduces the need for pharmaceutical means of induction of labor in postdates pregnancy.41 There was no increased risk for cesarean section or maternal or neonatal infection. Adverse effects include maternal discomfort, vaginal bleeding, and irregular contractions. Transcervical Foley Catheter or Cook Catheter Insertion This approach involves placing a 30-mL Foley catheter bulb or an inflatable Cook catheter transcervically, inflating it with sterile saline solution, and applying maintenance traction or simply leaving it in place (Fig. 53.1).
Dosage The dose is one 10-mg pessary intravaginally. The insert releases 0.3 mg/hour over 12 hours. Remove at 12 hours, at the onset of active labor, or if uterine hyperstimulation occurs. The agent is available as a 10-mg sustained-release insert. It is also available as an intravaginal tablet or gel. Precautions Uterine hyperstimulation, fetal distress, uterine rupture, bronchospasm, abdominal cramps, headache, nausea, diarrhea
Mechanical Methods Potential advantages of mechanical methods, compared with pharmacological methods, for the induction of labor in postdates pregnancy include simplicity of use, lower cost, and reduction of side effects, such as uterine hyperstimulation and fetal distress. However, special attention should be paid to contraindications such as a low-lying placenta, risk for infection, and maternal discomfort.
FIG. 53.1 □ Cook cervical ripening balloon. (© 2012; Lisa Clark, courtesy Cook Medical.)
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A Cochrane review looked at 71 studies and concluded that induction of labor with mechanical methods resulted in a similar rate of cesarean section as prostaglandins with equal efficacy of achieving vaginal delivery in 24 hours and a lower risk for uterine hyperstimulation.42 When
compared with oxytocin alone, the rate of cesarean section is lower with mechanical methods. Complications include acute febrile reaction, pain, vaginal bleeding, and altered fetal presentation.
PREVENTION PRESCRIPTION • W omen can be encouraged in the preconception period to track their menstrual cycles and sexual activity closely to aid in accurate pregnancy dating. When women are unsure of their pregnancy dates, first-trimester ultrasound reduces the number of women later incorrectly classified as having postdates pregnancies. • Good self-care in pregnancy, including aromatherapy, good nutrition, massage, sexual
intercourse, spiritual practices, chiropractic, and yoga during the latter weeks of pregnancy may serve to relax the mother and allow the natural rise of oxytocin and reduction of stress hormones, thus resulting in a greater likelihood of spontaneous onset of labor.43-45 • Membrane sweeping, done routinely at 39 weeks, may also reduce the risk for a pregnancy that continues beyond 41 weeks.
THERAPEUTIC REVIEW These therapeutic options for prevention of postdates pregnancy and induction of labor in postdates pregnancy may be considered in the healthy, term patient with no medical complications that would make delivery urgent. NUTRITION • Pineapple consumption is commonly recommended for labor induction. Although pineapple has no proven benefit, the risks of this intervention are low. SUPPLEMENTS • Castor oil has a long history of use for labor induction. It is considered safe, but it has not been proven effective. Side effects include nausea. Doses are not standardized. • Evening primrose oil use lacks data on efficacy. The dose is two capsules intravaginally at bedtime, starting at 38 weeks of pregnancy. This supplement should not be used orally in pregnancy. • The homeopathic remedies caulophyllum and cimicifuga can be dosed at 200 C potency by alternating 1 pellet of each remedy every 30 minutes for a total of six doses in 24 hours to help stimulate labor. The benefit is unknown, and risks are minimal. BOTANICALS • Red raspberry leaf, taken as 1–3 cups of tea daily during the third trimester, may reduce the risk for postdates pregnancy. • Despite a strong history of use, black cohosh and blue cohosh should be avoided in pregnancy because of safety concerns until more data are available. BIOMECHANICAL THERAPY • Unilateral breast stimulation can be done for 1 hour per day for 3 consecutive days to induce labor at term.
C
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• Shiatsu may reduce the risk for postdates pregnancy.
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ACUPUNCTURE • Evidence is mixed on the effectiveness of acupuncture to reduce the risk for postdates pregnancy, for cervical ripening, and for labor induction. Acupuncture is considered safe.
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LIFESTYLE • Sexual intercourse may not be effective for reducing the risk for postdates pregnancy.
PHARMACEUTICALS • Misoprostol is commonly used for cervical ripening and labor induction, despite a lack of approval by the FDA for this indication. See the doses and A precautions discussed in the text. • Oxytocin may be used to induce uterine contractions in postdates pregnancy when cervical conditions are favorable. See the doses and precautions A discussed in the text. • Vaginal prostaglandins may be used for cervical ripening and labor induction, and they are a good choice for postdates pregnancy in patients with unfavorable cervical conditions. See the doses and A precautions discussed in the text. MECHANICAL THERAPY • Amniotomy may be used to induce or augment labor, and it may be more beneficial in multiparous A women. • Membrane sweeping can be considered routinely at 39 weeks to reduce the risk for postdates pregA nancy. • Transcervical Foley catheter insertion or Cook catheter insertion can be done for cervical ripening in postdates pregnancy, and it may have lower risks A than pharmaceutical ripening agents.
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Key Web Resources American College of Obstetricians and Gynecologists: Patient handout on postdates pregnancy American College of Nurse-Midwives: Consumer information on pregnancy and midwifery ACOG Guidelines: Management of late-term and postterm pregnancies
REFERENCES References are available online at ExpertConsult.com.
http://www.acog.org/Patients/FAQs/What-to-Expect-AfterYour-Due-Date http://www.mymidwife.org/ http://contemporaryobgyn.modernmedicine.com/ contemporary-obgyn/news/acog-guidelines-management-late-term-and-postterm-pregnancies?page=full
REFERENCES 1. ACOG Committee on Practice Bulletins-Obstetrics: ACOG Practice Bulletin. Clinical management guidelines for obstetriciansgynecologists, Number 55, September 2004 (replaces practice pattern number 6, October 1997). Management of postterm pregnancy, Obstet Gynecol 104:639–646, 2004. 2. Gülmezoglu AM, Crowther CA, Middleton P: Induction of labour for improving birth outcomes for women at or beyond term, Cochrane Database Syst Rev 4:CD004945, 2006. 3. Olesen AW, Westergaard JG, Olsen J: Perinatal and maternal complications related to postterm delivery: a national registerbased study, 1978-1993, Am J Obstet Gynecol 189:222–227, 2003. 4. Eagle WA: A recommendation for the definition of “late term” (near term) and the weight-gestational age classification system, Semin Perinatol 30:2–7, 2006. 5. MacKenzie IZ: Induction of labour at the start of the new millennium, Reproduction 131:989–998, 2006. 6. Neilson JP: Ultrasound for fetal assessment in early pregnancy, Cochrane Database Syst Rev 4:CD007058, 1998. 7. Westfall RE, Benoit C: The rhetoric of “natural” in natural childbirth: childbearing women’s perspectives on prolonged pregnancy and induction of labour, Soc Sci Med 59:1397–1408, 2004. 8. Gaspani L, Limiroli E, Ferrario P, et al.: In vivo and in vitro effects of bromelain on PGE(2) and SP concentrations in the inflammatory exudates of rats, Pharmacology 65:83–86, 2002. 9. Tiran D: Complementary therapies: your questions answered. Use of pineapple for induction of labour, Pract Midwife 12:33–34, 2009. 10. McFarlin BL, Gibson MH, O’Rear J, et al.: A national survey of herbal preparation use by nurse-midwives for labor stimulation: review of the literature and recommendations for practice, J Nurse Midwifery 44:602–603, 1999. 11. Tunaru S, Althoff TF, Nüsing RM, et al.: Castor oil induces laxation and uterus contraction via ricinoleic acid activating prostaglandin EP3 receptors, Proc Natl Acad Sci U S A 109:9179–9184, 2012. 12. Kelly AJ, Kavanagh J, Thomas J: Castor oil, bath and/or enema for cervical priming and induction of labour, Cochrane Database Syst Rev 7:CD003099, 2013. 13. Boel ME, Lee SJ, Rijken MJ, et al.: Castor oil for induction of labour: not harmful, not helpful, Aust N Z J Obstet Gynaecol 49: 499–503, 2009. 14. Wedig KE, Whitsett JA: Down the primrose path: petechiae in a neonate exposed to herbal remedy for parturition, J Pediatr 152:140, 2008. 15. Dove D, Johnson P: Oral evening primrose oil: its effect on length of pregnancy and selected intrapartum outcomes in low risk nulliparous women, J Nurse Midwifery 44:320–324, 1999. 16. Smith CA: Homeopathy for induction of labour, Cochrane Database Syst Rev 4:CD003399, 2003. 17. Kistin S, Newman A: Induction of labor with homeopathy: a case report, J Midwifery Womens Health 52:303–307, 2007. 18. Tyler VE: The honest herbal, ed 3, New York, 1993, Pharmaceutical Products Press. 19. Simpson M, Parsons M, Greenwood J, et al.: Raspberry leaf in pregnancy: its safety and efficacy in labor, J Midwifery Womens Health 46:51–59, 2001. 20. Rojas-Vera Patel AV, Dacke CG: Relaxant activity of raspberry (Rubus idaeus) leaf extract in guinea pig ileum in vitro, Phytother Res 16:665–668, 2002. 21. Mills E, Dugoua JD, Perri D, et al.: Herbal medicines in pregnancy & lactation: an evidence based approach, London/New York, 2006, Taylor & Francis.
22. McFarlin BL, Gibson MH, O’Rear J, Harman P: A national survey of herbal preparation use by nurse-midwives for labor stimulation. Review of the literature and recommendations for practice, J Nurse Midwifery 44:205–216, 1999. 23. Gunn TA, Wright IM: The use of black and blue cohosh in labour, N Z Med J 109:410–411, 1996. 24. De Smet PA, Keller K, Hansel R, et al.: Adverse effects of herbal drugs (vol. 2). Berlin, 1993, Springer. 25. Satchithanandam S, Grundel E, Roach J, et al.: Alkaloids and saponins in dietary supplements of blue cohosh (Caulophyllum thalictroides) J AOAC Int 91(1):21–32, 2008. 26. Dugoua JJ, Seely D, Perri D, et al.: Safety and efficacy of blue cohosh (Caulophyllum thalictroides) during labour and lactation, Can J Clin Pharmacol 15:e66–e73, 2008. 27. Curtis P: Breast stimulation to augment labour: history, mystery and culture, Birth 26:123–126, 1999. 28. Kavanagh J, Kelly AJ, Thomas J: Breast stimulation for cervical ripening and induction of labour, Cochrane Database Syst Rev 3:CD003392, 2005. 29. Lenke RR, Nemes JR: Use of nipple stimulation to obtain contraction stress test, Obstet Gynecol 63:345, 1984. 30. Adair C: Nonpharmacologic approaches to cervical priming and labor induction, Clin Obstet Gynecol 43:447–454, 2000. 31. Yates S: Supporting women with shiatsu: another tool for keeping birth normal, MIDIRS Midwifery Dig 8:422–424, 1998. 32. Ingram J, Domagala C, Yates S: The effects of shiatsu on post-term pregnancy, Complement Ther Med 13:11–15, 2005. 33. Smith CA, Crowther CA, Grant SJ: Acupuncture for induction of labour, Cochrane Database Syst Rev 8:CD002962, 2013. 34. Kavanagh J, Kelly AJ, Thomas J: Sexual intercourse for cervical ripening and induction of labour, Cochrane Database Syst Rev 2:CD003093, 2001. 35. Hofmeyr GJ, Gülmezoglu AM, Pileggi C: Vaginal misoprostol for cervical ripening and induction of labour, Cochrane Database Syst Rev 10:CD000941, 2010. 36. Alfirevic Z, Weeks A: Oral misoprostol for induction of labor, Cochrane Database Syst Rev 2:CD001338, 2006. 37. Muzonzini G, Hofmeyr GJ: Buccal or sublingual misoprostol for cervical ripening and induction of labor, Cochrane Database Syst Rev 4:CD004221, 2004. 38. Alfirevic Z, Kelly AJ, Dowswell T: Intravenous oxytocin alone for cervical ripening and induction of labour, Cochrane Database Syst Rev 4:CD003246, 2009. 39. Thomas J, Fairclough A, Kavanagh J, Kelly AJ: Vaginal prostaglandin (PGE2 and PGF2a) for induction of labour at term, Cochrane Database Syst Rev 6:CD003101, 2014. 40. Bricker L, Luckas M: Amniotomy alone for induction of labour, Cochrane Database Syst Rev 4:CD002862, 2000. 41. Boulvain M, Stan CM, Irion O: Membrane sweeping for induction of labour, Cochrane Database Syst Rev 1:CD000451, 2005. 42. Jozwiak M, Bloemenkamp KW, Kelly AJ, et al.: Mechanical methods for induction of labour, Cochrane Database Syst Rev 3:CD001233, 2012. 43. McNabb MT, Kimber L, Haines H, et al.: Does regular massage from late pregnancy to birth decrease maternal pain perception during labour and birth? A feasibility study to investigate a programme of massage, controlled breathing and visualization, from 36 weeks of pregnancy until birth, Complement Ther Clin Pract 12:222–231, 2006. 44. Fields N: Yoga: empowering women to give birth, Pract Midwife 11:30–32, 2008. 45. Beddoe AE, Lee KA: Mind-body interventions during pregnancy, J Obstet Gynecol Neonatal Nurs 37:165–175, 2008.
541.e1
Postdates Pregnancy D. Jill Mallory, MD
PATHOPHYSIOLOGY
INTEGRATIVE THERAPY
Postdates or postterm pregnancy is defined as a pregnancy that extends to or beyond 42 weeks of gestation (294 days or estimated date of delivery [EDD] plus 14 days). A normal pregnancy lasts approximately 40 weeks from the start of a woman’s last menstrual period, but any pregnancy that lasts between 37 and 42 weeks is considered normal. Approximately 4%–7% of all singleton pregnancies extend to 42 weeks or 14 days beyond the EDD.1 Postterm pregnancy is associated with a higher perinatal mortality rate (stillbirth and newborn death within the first week) and a higher risk for complications during delivery, such as an emergency cesarean delivery, shoulder dystocia, postpartum hemorrhage, birth asphyxia, meconium aspiration syndrome, and neonatal birth injury.2 Current research suggests that the lowest infant mortality rate is achieved when pregnant women have completed at least 41 weeks of gestation before labor is induced and when induction occurs before or at 42 weeks of gestation, although the absolute risk for problems from delivering beyond 42 weeks is low.2 The overall risk for perinatal death is estimated at 0.4% in women who deliver beyond 42 weeks of gestation and 0.3% for women who deliver between 37 and 42 weeks of gestation.3 Because of this small increase in perinatal mortality, the induction of labor is widely practiced at or before 42 weeks of gestation, and postterm pregnancy has become the most common reason for induction.4 Unfortunately, labor induction itself is not without risks. Obstetric problems associated with induction of labor in postterm pregnancy include cesarean section, prolonged labor, postpartum hemorrhage, and traumatic birth. These problems are more likely to result from induction when the uterus and cervix are not ready for labor.2 Furthermore, induction of labor brings with it increased risks of uterine rupture, uterine hyperstimulation, fetal distress, and instrumentation.5 Very few studies have considered women’s experiences and opinions when it comes to the timing of inducing labor, and for women seeking a natural, unmedicated labor and birth, induction poses many philosophical challenges. Accurate dating is obviously important for reducing the need of induction, and studies have shown that early ultrasound is associated with a reduced incidence of pregnancies misclassified as postterm.6 When women have accurate pregnancy dating and are approaching 41 weeks of gestation, many may seek nonpharmaceutical measures of cervical ripening and labor induction. One small study of 50 women showed that many were opposed to medical induction of labor, yet they used self-help measures to stimulate labor at home.7 More research is needed in the realm of nonpharmaceutical cervical ripening and labor induction options for women who have postdate pregnancies.
Nutrition Pineapple Pineapple (Ananas comosus), which contains the compound bromelain, has historical medicinal use both as a whole food and in extract form. Bromelain has been proposed as the active ingredient, and it is present only in the fresh fruit because the canning process destroys it. Bromelain has been used to elicit uterine contractions as a means of shortening labor. Some animal model research suggests that instead of increasing cervical prostaglandins, bromelain may actually inhibit them.8 No research is available on the possible effectiveness of bromelain for induction of human uterine contractions, although this use is widely suggested in lay pregnancy resources. Some investigators suggest that pineapple’s effects on labor may result from gastrointestinal stimulation by fiber and sugar, thus affecting local neural pathways.9 No known risks are associated with pineapple use in pregnancy.
Supplements Castor Oil Castor oil, derived from the bean of the castor plant (Ricinus communis), has a very rich history of use for labor stimulation that dates back to ancient Egypt. One survey completed in 1999 found that 93% of U.S. midwives reported using castor oil to induce labor.10 Despite this prevalence, research into the use of castor oil has been limited. A recent study in mice found that the castor oil metabolite ricinoleic acid activated intestinal and uterine smooth muscle cells via prostaglandin E2 receptor 3 (EP3) prostanoid receptors.11 This may explain its mechanism of action in humans. Three trials were included in a recent Cochrane review looking at castor oil for labor induction.12 It included 233 women at term and compared ingestion of castor oil with no treatment/ placebo. Outcomes evaluated included cesarean section rate, meconium staining of amniotic fluid, instrumental delivery, and Apgar scores. All women who ingested castor oil had nausea; otherwise, outcomes were not significantly different from those in women who did not ingest castor oil. A retrospective observational study done in Thailand of 612 women looked at the timing of delivery, fetal distress, meconium-stained amniotic fluid, tachysystole of the uterus, uterine rupture, abnormal maternal blood pressure during labor, Apgar scores, neonatal resuscitation, stillbirth, postpartum hemorrhage, severe diarrhea, and maternal death.13 No differences were seen 535
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in outcomes between the women who ingested castor oil and the women who did not. This finding suggests that castor oil is safe to use but may not be helpful. Prospective randomized controlled trials are needed. Evening Primrose Oil Evening primrose oil (Oenothera biennis) is often used for several health conditions of women, including breast pain (mastalgia), menopausal and premenstrual symptoms, and labor induction or augmentation. It contains the amino acid tryptophan and an unusually high content of essential fatty acids, especially cis-linoleic acid (CLA) and gamma-linoleic acid (GLA).10 These fatty acids are prostaglandin precursors, which may explain traditional use of the oil for stimulating cervical ripening.10 This supplement is used widely during the last month of pregnancy by midwives in the United States both for cervical ripening and to decrease the incidence of postdates pregnancy.10 Evening primrose oil is traditionally administered as one to two capsules intravaginally at bedtime, starting after 37 completed weeks of pregnancy. There has been one case report of an infant born with petechiae and ecchymosis after its mother took primrose oil a week before giving birth.14 One study investigated oral administration and showed that this route was not effective.15 Furthermore, the oral use of evening primrose oil during pregnancy may also be associated with more prolonged labor and an increased risk for premature rupture of membranes, arrest of descent, oxytocin use, and vacuum extraction.15 This finding is not surprising because oral administration during pregnancy was never a traditional use. Larger trials assessing the efficacy of vaginal administration are needed.
Homeopathy Homeopathy is a safe choice for pregnant women and babies because the remedies used in this system of healing have no pharmacological action.16 In the United States, the use of homeopathic remedies has increased, and a survey among nurse-midwives in North Carolina reported that 30% recommend homeopathic substances for use during pregnancy. The two most common homeopathic remedies used for labor induction are cimicifuga (homeopathic black cohosh) and caulophyllum (homeopathic blue cohosh), which are believed to act directly on the uterus and cervix. These remedies have a long history of use around the world for labor stimulation, especially in Europe and India.17 Caulophyllum is used either to induce labor or augment labor if uterine contractions are short and irregular or when uterine contractions stop. Caulophyllum and cimicifuga are both indicated for dysfunctional uterine contractions and are thought to help initiate a coordinated and effective contraction pattern. Cimicifuga is used specifically to ease the fear of labor and delivery in women who have a history of traumatic childbirth, miscarriage, or abortion.18 Cimicifuga alone is administered as a single dose of 30 C or 200 C potency every 30 minutes for at least 2 hours or together with
caulophyllum 200 C, alternating doses of the two remedies for a total of six doses in 24 hours. Other remedies that are commonly used for labor induction include aconite, arsenicum, gelsemium, phosphorus, and pulsatilla. These are all given in 200 C potency as a single dose (two pellets).19 A 2003 Cochrane review examined the use of caulophyllum, cimicifuga, and some of these other homeopathic remedies.16 The review assessed only two studies comparing homeopathy and placebo for cervical ripening or labor induction and found that small sample sizes and insufficient detail in the research made it impossible to draw any meaningful clinical conclusions. More research needs to be conducted to determine whether homeopathy is a potentially viable alternative to oxytocin and prostaglandins for labor induction. Furthermore, studies should be designed to incorporate individualized homeopathic treatments, prescribed by a trained homeopath, to account for the individualized nature of this modality.
For labor induction, caulophyllum and cimicifuga homeopathic remedies are as follows: 30 C or 200 C given every 30 minutes,1 pellet of each remedy, for a total of six doses in 24 hours. No remedy is given the next day. Repeat the same protocol on day 3 if needed. Other remedies to consider are gelsemium for fear of birth and pulsatilla when contractions come and go, but labor never becomes established.
Botanicals Red Raspberry Leaf Red raspberry leaf (Rubus idaeus, Rubus occidentalis) has been used as a uterine tonic and general pregnancy tea for at least two centuries. Although this botanical is often mistakenly recommended to induce labor, its actual role is to increase blood flow to the uterus and aid the uterine muscle fibers in more organized contraction. Studies indicate that some of the plant components, such as fragrine, an alkaloid, do act directly on smooth muscle.20 Animal studies show conflicting data in terms of the herb’s effect on uterine muscle. Some studies show a contractile effect, whereas others show a relaxing effect. Historical uses include prevention of miscarriage, prevention of postdates pregnancy, decrease of discomfort in prodromal labor, and decrease of morning sickness. Red raspberry leaf was also probably consumed for nutritional support because the plant contains many nutrients, including vitamins A, C, and E, as well as calcium, iron, and potassium. Overall, the herb does seem to reduce the risk for postdates pregnancy and appears safe for general use.21 One randomized controlled trial of 192 women showed no adverse effects to mother or baby, a shorter second stage of labor (a mean difference of 10 minutes), and a lower rate of forceps use.19 One retrospective, observational study of more than 150 women also found that red raspberry leaf reduced the risk for postdates pregnancy, but more conclusive data are needed.16
53 Postdates Pregnancy Dosage It is most commonly consumed as a tea, taken as 1–3 cups daily. Precautions Generally regarded as safe
Black Cohosh This herb (Actaea racemosa) also has a long history of use. Native Americans mixed it with chamomile, ginger, and raspberry tea to induce menses and labor. The active compounds in black cohosh include terpene glycoside fractions, such as actein and cimifugoside, which have been associated with an estrogenic effect and are thought to reduce levels of pituitary luteinizing hormone, thus decreasing ovarian production of progesterone.18 This effect may contribute to the initiation of uterine contractions because the relaxing effect of the high levels of progesterone on the uterine muscle decreases before the initiation of labor. However, a systematic review on the use of black cohosh in labor found no evidence of efficacy.22 One of its alkaloids, caulosaponin, causes coronary blood vessel constriction and direct myocardial toxicity in a dose-dependent manner. This poses challenges to practitioners because the doses present in over-the-counter products may be difficult to verify. At least one case report has been published of toxicity in an infant whose mother was given an unknown dose of black cohosh at term.23 At this time, the German Commission E, an expert committee established by the German Ministry of Health that evaluates herbal products, does not recommend the use of black cohosh in pregnancy.24 Blue Cohosh The herb blue cohosh (Caulophyllum thalictroides) also has a long tradition of use as a uterine tonic. It was traditionally used by Native Americans during 2–3 weeks before the onset of labor.22 Between 1882 and 1905, blue cohosh was listed in the United States Pharmacopoeia for labor induction.22 Over-the-counter preparations of blue cohosh contain varying amounts of triterpene glycosides, which have documented oxytocic effects.25 No studies are available on efficacy. Three case reports are available that demonstrate possible adverse neonatal effects, such as fetal hypoxia, myocardial infarction, and congestive cardiac failure.26 Whether these effects resulted from the herb itself is not known, given that herbs are often used in combination with other plants, and adulteration and contamination problems can occur. Until further research on this plant is done, it is best avoided for labor induction.
At this time, the use of blue and black cohosh is best avoided in pregnant women because of safety concerns.
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Biomechanical Therapy Breast Stimulation Breast stimulation has historically been used to induce or augment labor since as early as the eighteenth century.27 Stimulation of the breast is thought to increase the production of endogenous oxytocin in pregnant and nonpregnant women. The most commonly used protocol for breast stimulation involves using either a manual or electric breast pump, manual massage around the areola of the nipple, or rolling the base of the nipple. Typical hospital protocols recommend stimulating each breast individually for 10 minutes each, with a 10-minute rest period following, for a total of four cycles. The Cochrane Collaboration performed a systematic review of six trials with a total of 719 participants that compared breast stimulation with no intervention to induce labor in women at term.28 The review found that compared with no intervention, breast stimulation significantly reduced the number of women who had not gone into labor at 72 hours.28 This difference was not significant in women with an unfavorable cervix. Breast stimulation also reduced the risk for postpartum hemorrhage by 84%.28 It did not seem to have an effect on cesarean section rates. No incidences of uterine hyperstimulation were noted. Breast stimulation for labor induction allows women’s participation in the induction process and has the advantage of being a low-cost and nonpharmaceutical means of labor induction. Observational studies, however, have shown a link between bilateral breast stimulation and uterine hyperstimulation.29 For this reason, unilateral stimulation is typically recommended. Concerns have been raised regarding possible adverse effects on placental perfusion; however, the incidences of abnormal fetal heart rate tracings are similar to those found with oxytocin use.30 Continuous electronic fetal monitoring is typically used with breast stimulation in the hospital setting. A common protocol used by women in their homes at term is unilateral breast stimulation done for 1 hour per day for 3 consecutive days. Until safety issues have been more thoroughly evaluated, this technique should not be used in high-risk populations. Shiatsu Shiatsu is an ancient form of massage based on Chinese acupuncture theory that often includes the use of breathing and stretching. Shiatsu can be done through the clothes or on bare skin and uses static pressure, which can vary from light holding to deep physical pressure applied with the palm of the hand or thumb. Shiatsu lends itself well to maternity settings because specific shiatsu techniques can be taught to birth partners or practitioners. It has historically been used in midwifery practices to induce or augment labor.31 One small pilot study evaluated shiatsu for induction and augmentation of postterm labor.32 Sixty-six women with postterm pregnancies were studied in a hospital-based midwifery practice. Pregnant women
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were taught to massage three acupuncture points in conjunction with breathing techniques and exercises. The controls attended the same clinic, but they were not taught the techniques. The investigators found that the women with postterm pregnancies who used shiatsu were significantly more likely to have spontaneous labor than were the study participants who did not use shiatsu.
Bioenergetics Acupuncture As part of the ancient system of medicine, known as traditional Chinese medicine, acupuncture has been used in pregnancy for thousands of years. Modern studies have evaluated the insertion of fine needles into specific points on the body, as well as the use of mild electrical currents through these needles, known as electroacupuncture. A 2013 Cochrane Systematic Review evaluated acupuncture for inducing labor.33 The investigators identified 14 trials that included 2220 women for review. Acupuncture was compared with sham acupuncture or usual cases. Most of the trials were undertaken in Western countries. No trial reported on the achievement of vaginal delivery in 24 hours or uterine hyperstimulation. The use of acupuncture did not seem to affect cesarean section rates or neonatal seizure rates. Acupuncture did seem to increase cervical ripening; however, it did not seem to shorten labor. There were no other statistically significant differences between the groups, including no differences in neonatal morbidity or maternal mortality. Overall, the limited studies to date suggest that acupuncture appears safe for inducing labor, has no known adverse effects on the fetus, and may be effective. The inherent difficulties in blinding for acupuncture treatment make the study of this technique challenging. Given its safety profile, it may be worth trying in patients who wish to avoid pharmaceutical induction of labor. Table 53.1 provides acupuncture points that patients can massage at home to stimulate labor.
Lifestyle Sexual Intercourse Unprotected sexual intercourse is thought to encourage the onset of labor by two means. One is the release
TABLE 53.1 Acupressure Points for Induction of Labor 1. Midway along the top of the trapezius muscles, if you were to draw a line from the acromion to C7 2. The motion sickness point at the angle between the first and second metacarpals 3. In the semicircle around the distal medial and lateral malleoli 4. The little toe, all over Massage these points for at least 2–3 minutes each. From Mallory J. Integrative care of the mother-infant dyad. Prim Care. 2010;37:149–163.
of endogenous oxytocin in the mother, and the other is cervical ripening caused by seminal prostaglandins. A Cochrane review looked at an observational study of 28 women at term. Unprotected intercourse for three consecutive nights neither significantly changed Bishop scores (1.0 with coitus vs. 0.5 controls; P > .05) nor increased the number of women who went into labor at the end of 3 days (relative risk, 0.99; 95% confidence interval, 0.45–2.20).34 Sexual intercourse in pregnancy is considered safe, provided the absence of placenta previa, rupture of membranes, or active genital infection.30 Larger studies are needed to determine whether sexual intercourse has any significant effect on reducing the risk for postdates pregnancy.
Pharmaceuticals Misoprostol Misoprostol is a prostaglandin E1 analog widely used for off-label indications such as induction of labor in postdates pregnancy. This hormone is given by insertion through the vagina or rectum or by mouth to ripen the cervix and elicit uterine contractions. A Cochrane review looked at 121 trials and found that small doses (25 mcg every 4 hours) of misoprostol vaginally were as effective as other methods of labor induction.35 Larger doses of misoprostol were found to be more effective than prostaglandins for labor induction, and larger doses also reduced the need for additional oxytocin. Another Cochrane review found that the oral route of administration may be preferable to the vaginal route.36 Compared with the vaginal route, oral route of administration was associated with a lower rate of babies born with low Apgar scores and a lower rate of postpartum hemorrhage but with a higher rate of meconium-stained amniotic fluid. A third Cochrane review has looked at buccal or sublingual administration.37 Data on these routes of administration are more limited; however, there was a trend toward a lower cesarean section rate, a reduced need for oxytocin augmentation, and an increased rate of vaginal delivery in 24 hours. More studies are needed to establish the optimal buccal/sublingual dosage. The main risk for misoprostol use is hyperstimulation of the uterus, and this risk seems to increase with increasing dose. At this time, misoprostol is not approved by the Food and Drug Administration (FDA) for induction of labor.
Dosage The most common dose used in the United States is 25 mcg intravaginally every 4 hours (maximum, 50 mcg). Wait for more than 4 hours after the last dose before adding oxytocin. The most common oral dose used is 50 mcg. Misoprostol comes in 100- and 200-mcg tablet formulations. Precautions Uterine hyperstimulation, uterine rupture, diarrhea, nausea, vomiting, headache Although misoprostol is commonly used for labor induction in the United States, it has not been approved by the FDA for this use.
53 Postdates Pregnancy
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Oxytocin
Amniotomy
Oxytocin is the most common induction agent used worldwide. It is used alone, in combination with amniotomy, or following cervical ripening with other pharmacological or nonpharmacological methods. Oxytocin is a synthetic analog of the natural labor hormone by the same name. It binds to oxytocin receptors in the uterine myometrium, increases intracellular calcium, and stimulates uterine contractions. A Cochrane review of more than 61 studies concluded that it is safe and effective.38 A black box warning placed on the drug by the FDA states that oxytocin is not to be used for elective labor induction.
The deliberate rupture of membranes may be sufficient to bring about labor without the use of pharmaceuticals. This approach has the advantage of being cheap, but it may be uncomfortable for some women. If the time between amniotomy and delivery of the baby is long, infection may occur. The risk for umbilical cord prolapse is also increased, especially if the fetal head is ballotable at the time of membrane rupture. Anecdotal reports note that amniotomy may be less beneficial in nulliparous women. More evidence is needed regarding effectiveness compared with placebo or compared with other methods of induction of labor.40
Dosage Start with 0.5–2 milliunits/minute and increase by 1–2 milliunits/minute every 15–40 minutes until the uterine contraction pattern is established. The maximum for induction is 40 milliunits/minute. Oxytocin is available in intravenous and intramuscular preparations. Precautions Increased use of epidural anesthesia, uterine hyperstimulation, uterine rupture, abruptio placentae, fetal distress, nausea, vomiting
Vaginal Prostaglandins (PGE2 and PGF2alpha) Prostaglandins have been used for the induction of labor since the 1960s. These drugs are synthetic analogs of the body’s naturally occurring prostaglandins, which function to ripen the cervix and bring about contractions. A Cochrane review looked at 70 randomized controlled studies of various forms of prostaglandins and found them to be a safe and effective means of labor induction.39 Prostaglandin E2 is the most commonly used type, and it increases the likelihood of vaginal birth in 24 hours and may reduce the risk for cesarean section by 10%.39
Membrane Sweeping Sweeping of the membranes, also known as membrane stripping, is a simple manual technique usually done in the outpatient setting. The technique involves inserting a finger into the cervical os during a sterile vaginal examination and sweeping the finger in a circular motion to detach the membranes from the lower uterine segment. This method sometimes works to initiate labor by increasing the local production of prostaglandins. A Cochrane review of 72 studies found that sweeping of the membranes performed routinely for women at term was associated with a reduced frequency of pregnancy extending beyond 41 weeks.41 This method is considered safe and reduces the need for pharmaceutical means of induction of labor in postdates pregnancy.41 There was no increased risk for cesarean section or maternal or neonatal infection. Adverse effects include maternal discomfort, vaginal bleeding, and irregular contractions. Transcervical Foley Catheter or Cook Catheter Insertion This approach involves placing a 30-mL Foley catheter bulb or an inflatable Cook catheter transcervically, inflating it with sterile saline solution, and applying maintenance traction or simply leaving it in place (Fig. 53.1).
Dosage The dose is one 10-mg pessary intravaginally. The insert releases 0.3 mg/hour over 12 hours. Remove at 12 hours, at the onset of active labor, or if uterine hyperstimulation occurs. The agent is available as a 10-mg sustained-release insert. It is also available as an intravaginal tablet or gel. Precautions Uterine hyperstimulation, fetal distress, uterine rupture, bronchospasm, abdominal cramps, headache, nausea, diarrhea
Mechanical Methods Potential advantages of mechanical methods, compared with pharmacological methods, for the induction of labor in postdates pregnancy include simplicity of use, lower cost, and reduction of side effects, such as uterine hyperstimulation and fetal distress. However, special attention should be paid to contraindications such as a low-lying placenta, risk for infection, and maternal discomfort.
FIG. 53.1 □ Cook cervical ripening balloon. (© 2012; Lisa Clark, courtesy Cook Medical.)
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A Cochrane review looked at 71 studies and concluded that induction of labor with mechanical methods resulted in a similar rate of cesarean section as prostaglandins with equal efficacy of achieving vaginal delivery in 24 hours and a lower risk for uterine hyperstimulation.42 When
compared with oxytocin alone, the rate of cesarean section is lower with mechanical methods. Complications include acute febrile reaction, pain, vaginal bleeding, and altered fetal presentation.
PREVENTION PRESCRIPTION • W omen can be encouraged in the preconception period to track their menstrual cycles and sexual activity closely to aid in accurate pregnancy dating. When women are unsure of their pregnancy dates, first-trimester ultrasound reduces the number of women later incorrectly classified as having postdates pregnancies. • Good self-care in pregnancy, including aromatherapy, good nutrition, massage, sexual
intercourse, spiritual practices, chiropractic, and yoga during the latter weeks of pregnancy may serve to relax the mother and allow the natural rise of oxytocin and reduction of stress hormones, thus resulting in a greater likelihood of spontaneous onset of labor.43-45 • Membrane sweeping, done routinely at 39 weeks, may also reduce the risk for a pregnancy that continues beyond 41 weeks.
THERAPEUTIC REVIEW These therapeutic options for prevention of postdates pregnancy and induction of labor in postdates pregnancy may be considered in the healthy, term patient with no medical complications that would make delivery urgent. NUTRITION • Pineapple consumption is commonly recommended for labor induction. Although pineapple has no proven benefit, the risks of this intervention are low. SUPPLEMENTS • Castor oil has a long history of use for labor induction. It is considered safe, but it has not been proven effective. Side effects include nausea. Doses are not standardized. • Evening primrose oil use lacks data on efficacy. The dose is two capsules intravaginally at bedtime, starting at 38 weeks of pregnancy. This supplement should not be used orally in pregnancy. • The homeopathic remedies caulophyllum and cimicifuga can be dosed at 200 C potency by alternating 1 pellet of each remedy every 30 minutes for a total of six doses in 24 hours to help stimulate labor. The benefit is unknown, and risks are minimal. BOTANICALS • Red raspberry leaf, taken as 1–3 cups of tea daily during the third trimester, may reduce the risk for postdates pregnancy. • Despite a strong history of use, black cohosh and blue cohosh should be avoided in pregnancy because of safety concerns until more data are available. BIOMECHANICAL THERAPY • Unilateral breast stimulation can be done for 1 hour per day for 3 consecutive days to induce labor at term.
C
C
C
C
B
1
2
1
1
1
C
2
A
1
• Shiatsu may reduce the risk for postdates pregnancy.
C
1
ACUPUNCTURE • Evidence is mixed on the effectiveness of acupuncture to reduce the risk for postdates pregnancy, for cervical ripening, and for labor induction. Acupuncture is considered safe.
B
1
C
1
LIFESTYLE • Sexual intercourse may not be effective for reducing the risk for postdates pregnancy.
PHARMACEUTICALS • Misoprostol is commonly used for cervical ripening and labor induction, despite a lack of approval by the FDA for this indication. See the doses and A precautions discussed in the text. • Oxytocin may be used to induce uterine contractions in postdates pregnancy when cervical conditions are favorable. See the doses and precautions A discussed in the text. • Vaginal prostaglandins may be used for cervical ripening and labor induction, and they are a good choice for postdates pregnancy in patients with unfavorable cervical conditions. See the doses and A precautions discussed in the text. MECHANICAL THERAPY • Amniotomy may be used to induce or augment labor, and it may be more beneficial in multiparous A women. • Membrane sweeping can be considered routinely at 39 weeks to reduce the risk for postdates pregA nancy. • Transcervical Foley catheter insertion or Cook catheter insertion can be done for cervical ripening in postdates pregnancy, and it may have lower risks A than pharmaceutical ripening agents.
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Key Web Resources American College of Obstetricians and Gynecologists: Patient handout on postdates pregnancy American College of Nurse-Midwives: Consumer information on pregnancy and midwifery ACOG Guidelines: Management of late-term and postterm pregnancies
REFERENCES References are available online at ExpertConsult.com.
http://www.acog.org/Patients/FAQs/What-to-Expect-AfterYour-Due-Date http://www.mymidwife.org/ http://contemporaryobgyn.modernmedicine.com/ contemporary-obgyn/news/acog-guidelines-management-late-term-and-postterm-pregnancies?page=full
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