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Postdate antenatal testing
GYNECOLOGY &OBsTltTRICS International Journal of Gynecology & Obstetrics 49 (1995) 145-147
Article
Postdate antenatal testing G. Ohel*“, N. Yaacobi”, N. Linderb, J. Younisa ‘Department of Obstetrics and Gynecology, Poriya Hospital, Tiberias, Israel bDepartment
of Neonatology. Sheba Medical Center, Tel-Hashomer, Tel-Aviv University, School of Medicine,
Tel-Aviv,
Israel
Received 13 December 1994;revision received 20 January 1995:accepted I February 1995
Abstract Objective: To test the effect on pregnancy outcome of a policy of very early commencementof postdate surveillance testing, and induction of labor at 42 weeks. Methods: Retrospective analysis of 2776 consecutive cephalic deliveries at 38-42 weeksof gestation. Management of the postdate pregnanciesincluded twice-weekly antenatal testing beginning at 40 completed weeksand elective induction of labor at 42 completed weeks.Pregnancy outcome parameterswere compared between the groups delivered at 38-40 weeks and at 41-42 weeks. Results: There were 2138 pregnancies delivered at 38-40 weeks and 638 at 41-42 weeks. The latter group had a statistically significant increase in the rate of cesareansection, mainly accounted for by an increasedrate of fetal distressand failure to progressin labor. Similarly the rate of instrumental vagina1 delivery, meconium in labor and macrosomia had a statistically significantly higher incidence in the postdate group. These differences in outcome were already apparent at 41 weeksof gestation. Conclusion: Despite early initiation of fetal surveillance, starting at 40 completed weeks,postdate pregnanciesare associated with an increased rate of emergencycesareansection, macrosomia and meconium in labor. Keywords:
Pregnancy; Postdates; Fetal surveillance
1. Introduction Postmaturity has long been known to be associated with increased perinatal morbidity and mortality [l]. Furthermore it has been shown that the incidence of complications increases significantly each week after 40 weeks of gestation [2,3]. Such data have dictated the now widespread protocols of fetal surveillance in postdate pregnancies. While, traditionally, fetal testing has begun at 42 * Corresponding author.
weeks, recent reports suggest the need for testing at an earlier gestational age [4,5]. The purpose of this study was to assess the perinatal impact of a policy of very early postdate testing starting at or within a few days of the expected date of confinement.
2. Materials and methods During a period of 20 months, starting January 1991, there were 3549 deliveries at the Poriya Hospital, Tiberias. Of these (excluding cases with
0020-7292/95/%09.500 1995 International Federation of Gynecology and Obstetrics SSDI 0020-7292(95)02357-I
146
G. Ohel et al. /International
Journal of Gynecology & Obstetrics 49 (1995) 145-147
n : t T
i
12fl 10
f=l I III
ii
841
I
had reached 42 completed weeks, or earlier in caseswith abnormal fetal test results. Clinical data were extracted regarding outcome of labor, indications for cesarean section, Apgar scores, the presenceof meconium and weight of the newborn for each week of gestation, from 38 weeks onwards. Chi-squared analysis was used to compare the clinical data of the three gestational agegroups (38-40, 41 and 42 weeks). 3. Results
Fig. 1. Frequency distribution of cesareansectionsaccording to indications and gestational age.
major fetal malformations), there were 2776 singleton, cephalic deliveries that occurred at 38-42 weeks of gestation: 2138 at 38-40 weeks, 516 at 41 weeks and 122 at 42 weeks. These pregnancies constitute the study population. Mothers admitted in labor had routine obstetric care that included continuous fetal heart rate monitoring for all cases.Postdatetesting began when pregnancies had reachedthe expecteddate of confinement. Gestational age was verified by early sonography. Tests were done every 3-4 days and included the non-stress test, sonographic assessmentof amniotic fluid volume and ambulatory fetal movement counting. Labor was induced in pregnancies that
There were no stillbirths or neonatal deaths in any of the gestational age groups studied. The cesarean section rate for all indications was 9Oh (192 cases)at 38-40 weeks, 7.9% (41 cases)at 41 weeksand 18%(22 cases)at 42 weeksof gestation. The rise in incidence was statistically significant (P < 0.002). While the rate of elective cesareansection decreasedfrom 4.7% of all deliveries at 38-40 weeksto 0.8% at 42 weeks, there was a significant increase in emergency cesarean sections: 4.3% at 38-40 weeks, 6.2% at 41 weeks (P < 0.059) and 17.3%at 42 weeks(P < 0.00001).Further analysis of cesareansection rates according to indications and gestational age is shown in Fig. 1 and Table 1. The rise in emergencycesareansectionswas due both to failure to progress in labor (10.7% of cases at 42 weeks) and to fetal distress (6.6% of casesat 42 weeks).The incidence of heavy neonates(above 4 kg), meconium staining of the amniotic fluid and instrumental deliveries was higher in postdate de-
Table 1 Perinatal outcome variables in different gestational age groups P-value
Week of gestation
Cesareansection (all indications) (%) Cesareansection (fetal distress) (%) Cesareansection (no progress) (%) Instrumental delivery (%) Meconium (%) Weight >4 kg (%) Apgar 1 min <7 (%) Apgar 5 min <7 (%)
38-40 (n = 2138)
41 (n = 516)
42 (n = 122)
9.0 2.5 1.8 4.3 11.3 4.0 4.4 0.9
7.9 3.7 2.5 8.7 15.9 6.6 4.1 0.8
18.0 6.6 10.7 6.6 21.3 5.7 7.4 1.6
c 0.002
G. Ohel et al. /International
Journal of Gynecology & Obstetrics 49 (1995) 145-147
liveries compared with those delivered at 38-40 weeks. These differences were statistically significant (Table 1). The incidence of low Apgar scores increased at 42 weeks (7.4% and 1.6% of casesat 1 and 5 min, respectively), but the differences from the earlier gestational age groups did not reach statistical significance (Table 1). 4. Discussion This study evaluated the possible advantagesof very early commencementof fetal surveillance in postdate pregnancies.The results demonstrate that while the overall neonatal outcome was good, the incidence of cesareansections in the postdate pregnancies was significantly increased. Analysis of cesarean section rates according to diagnosis demonstrated that their overall rise at 41 and 42 weeks occurred despite the anticipated reduced number of elective cesareansections. The increased rate was accounted for by the significant rise in emergencycesareansections. At 42 weeksthe incidenceof cesareansectionsfor failure to progressin labor and fetal distress was 17.3%.This rate was about four times greater than that at 38-40 weeks. Of importance is the finding that compared with 38-40 weeks,the incidence of emergencycesarean sections, instrumental deliveries, heavy neonates and the presence of meconium was already increasedat 41 weeks of gestation. Postdate pregnancy posesa special challenge to the clinician. In current day obstetric practice mature fetusesare expectedto have very low perinatal morbidity and a corrected perinatal mortality of zero. Yet such expectations have not beenfulfilled. Postdate perinatal complication rates are still higher than at term [2,3] and occasional fetal deaths still occur despite antepartum fetal surveillance [6-81. It has been suggestedthat such outcome may be improved by more frequent and earlier commencement of fetal testing [5,6]. Our results indicate that this may not be the case. Although the overall neonatal outcome in the postdate pregnancies was good, the increased
147
rates, in this group, of macrosomia, fetal distress and meconium in labor may have a potentially adverse effect on both mothers and neonates. A recent review on postdate pregnanciesanalyzed 11 randomized, controlled trials comparing a policy of induction of labor with a policy of expectant managementand serial fetal surveillance [9]. Meta-analysis of these trials shows that induced labor groups are less likely to have fetal distress, meconium-stained amniotic fluid, macrosomic babies and babies who die during the perinatal period. Women who undergo induction of labor are also lesslikely to undergo delivery by cesarean section or operative vaginal delivery [9]. In accord with these conclusions, the results of the present study demonstrate that despite very early fetal surveillance starting at 40 completed weeks of gestation, there is still a higher incidence of cesarean sections, operative deliveries, heavy babies and meconium. References [I] McClure-Browne JC. Postmaturity. Am J Obstet Gynecol 1963;85: 573-582. [2] Arias F. Predictability of complications associatedwith prolongation of pregnancy. Obstet Gynecol 1987; 70: 101-106. [3] Grauz JP, Heimler R. Asphyxia and gestational age. Obstet Gynecol 1983;62: 175-179. [4] Bochner CJ, Williams III J, CastroL, Medearis A, Hobel CJ, Wade M. The efficacy of starting postterm antenatal testing at 41 weeks as compared with 42 weeks of gestational age. Am J Obstet Gynecol 1988; 159: 550-554. [5] Guidetti DA, Divon MY, Langer 0. Postdate fetal surveillance: is 41 weeks too early? Am J Obstet Gynecol 1989; 161: 91-93. 161Barss VA, Frigoletto FD, Diamond F. Stillbirth after nonstresstesting. Obstet Gynecol 1985;65: 541-544. [7] Clement D, Schifrin BS, Kates RB. Acute oligohydramnios in postdate pregnancy. Am J Obstet Gynecol 1987; 157: 884-886. (81Grubb DK, Rabello YA, Paul RH. Post-term pregnancy: fetal death rate with antepartum surveillance. Obstet Gynecol 1992;79: 1024-1026. [9] Hannah ME. Postterm pregnancy: should all women have labour induced? A review of the literature. Fetal Mater Med Rev 1993;5: 3-17.
Article
Postdate antenatal testing G. Ohel*“, N. Yaacobi”, N. Linderb, J. Younisa ‘Department of Obstetrics and Gynecology, Poriya Hospital, Tiberias, Israel bDepartment
of Neonatology. Sheba Medical Center, Tel-Hashomer, Tel-Aviv University, School of Medicine,
Tel-Aviv,
Israel
Received 13 December 1994;revision received 20 January 1995:accepted I February 1995
Abstract Objective: To test the effect on pregnancy outcome of a policy of very early commencementof postdate surveillance testing, and induction of labor at 42 weeks. Methods: Retrospective analysis of 2776 consecutive cephalic deliveries at 38-42 weeksof gestation. Management of the postdate pregnanciesincluded twice-weekly antenatal testing beginning at 40 completed weeksand elective induction of labor at 42 completed weeks.Pregnancy outcome parameterswere compared between the groups delivered at 38-40 weeks and at 41-42 weeks. Results: There were 2138 pregnancies delivered at 38-40 weeks and 638 at 41-42 weeks. The latter group had a statistically significant increase in the rate of cesareansection, mainly accounted for by an increasedrate of fetal distressand failure to progressin labor. Similarly the rate of instrumental vagina1 delivery, meconium in labor and macrosomia had a statistically significantly higher incidence in the postdate group. These differences in outcome were already apparent at 41 weeksof gestation. Conclusion: Despite early initiation of fetal surveillance, starting at 40 completed weeks,postdate pregnanciesare associated with an increased rate of emergencycesareansection, macrosomia and meconium in labor. Keywords:
Pregnancy; Postdates; Fetal surveillance
1. Introduction Postmaturity has long been known to be associated with increased perinatal morbidity and mortality [l]. Furthermore it has been shown that the incidence of complications increases significantly each week after 40 weeks of gestation [2,3]. Such data have dictated the now widespread protocols of fetal surveillance in postdate pregnancies. While, traditionally, fetal testing has begun at 42 * Corresponding author.
weeks, recent reports suggest the need for testing at an earlier gestational age [4,5]. The purpose of this study was to assess the perinatal impact of a policy of very early postdate testing starting at or within a few days of the expected date of confinement.
2. Materials and methods During a period of 20 months, starting January 1991, there were 3549 deliveries at the Poriya Hospital, Tiberias. Of these (excluding cases with
0020-7292/95/%09.500 1995 International Federation of Gynecology and Obstetrics SSDI 0020-7292(95)02357-I
146
G. Ohel et al. /International
Journal of Gynecology & Obstetrics 49 (1995) 145-147
n : t T
i
12fl 10
f=l I III
ii
841
I
had reached 42 completed weeks, or earlier in caseswith abnormal fetal test results. Clinical data were extracted regarding outcome of labor, indications for cesarean section, Apgar scores, the presenceof meconium and weight of the newborn for each week of gestation, from 38 weeks onwards. Chi-squared analysis was used to compare the clinical data of the three gestational agegroups (38-40, 41 and 42 weeks). 3. Results
Fig. 1. Frequency distribution of cesareansectionsaccording to indications and gestational age.
major fetal malformations), there were 2776 singleton, cephalic deliveries that occurred at 38-42 weeks of gestation: 2138 at 38-40 weeks, 516 at 41 weeks and 122 at 42 weeks. These pregnancies constitute the study population. Mothers admitted in labor had routine obstetric care that included continuous fetal heart rate monitoring for all cases.Postdatetesting began when pregnancies had reachedthe expecteddate of confinement. Gestational age was verified by early sonography. Tests were done every 3-4 days and included the non-stress test, sonographic assessmentof amniotic fluid volume and ambulatory fetal movement counting. Labor was induced in pregnancies that
There were no stillbirths or neonatal deaths in any of the gestational age groups studied. The cesarean section rate for all indications was 9Oh (192 cases)at 38-40 weeks, 7.9% (41 cases)at 41 weeksand 18%(22 cases)at 42 weeksof gestation. The rise in incidence was statistically significant (P < 0.002). While the rate of elective cesareansection decreasedfrom 4.7% of all deliveries at 38-40 weeksto 0.8% at 42 weeks, there was a significant increase in emergency cesarean sections: 4.3% at 38-40 weeks, 6.2% at 41 weeks (P < 0.059) and 17.3%at 42 weeks(P < 0.00001).Further analysis of cesareansection rates according to indications and gestational age is shown in Fig. 1 and Table 1. The rise in emergencycesareansectionswas due both to failure to progress in labor (10.7% of cases at 42 weeks) and to fetal distress (6.6% of casesat 42 weeks).The incidence of heavy neonates(above 4 kg), meconium staining of the amniotic fluid and instrumental deliveries was higher in postdate de-
Table 1 Perinatal outcome variables in different gestational age groups P-value
Week of gestation
Cesareansection (all indications) (%) Cesareansection (fetal distress) (%) Cesareansection (no progress) (%) Instrumental delivery (%) Meconium (%) Weight >4 kg (%) Apgar 1 min <7 (%) Apgar 5 min <7 (%)
38-40 (n = 2138)
41 (n = 516)
42 (n = 122)
9.0 2.5 1.8 4.3 11.3 4.0 4.4 0.9
7.9 3.7 2.5 8.7 15.9 6.6 4.1 0.8
18.0 6.6 10.7 6.6 21.3 5.7 7.4 1.6
c 0.002
G. Ohel et al. /International
Journal of Gynecology & Obstetrics 49 (1995) 145-147
liveries compared with those delivered at 38-40 weeks. These differences were statistically significant (Table 1). The incidence of low Apgar scores increased at 42 weeks (7.4% and 1.6% of casesat 1 and 5 min, respectively), but the differences from the earlier gestational age groups did not reach statistical significance (Table 1). 4. Discussion This study evaluated the possible advantagesof very early commencementof fetal surveillance in postdate pregnancies.The results demonstrate that while the overall neonatal outcome was good, the incidence of cesareansections in the postdate pregnancies was significantly increased. Analysis of cesarean section rates according to diagnosis demonstrated that their overall rise at 41 and 42 weeks occurred despite the anticipated reduced number of elective cesareansections. The increased rate was accounted for by the significant rise in emergencycesareansections. At 42 weeksthe incidenceof cesareansectionsfor failure to progressin labor and fetal distress was 17.3%.This rate was about four times greater than that at 38-40 weeks. Of importance is the finding that compared with 38-40 weeks,the incidence of emergencycesarean sections, instrumental deliveries, heavy neonates and the presence of meconium was already increasedat 41 weeks of gestation. Postdate pregnancy posesa special challenge to the clinician. In current day obstetric practice mature fetusesare expectedto have very low perinatal morbidity and a corrected perinatal mortality of zero. Yet such expectations have not beenfulfilled. Postdate perinatal complication rates are still higher than at term [2,3] and occasional fetal deaths still occur despite antepartum fetal surveillance [6-81. It has been suggestedthat such outcome may be improved by more frequent and earlier commencement of fetal testing [5,6]. Our results indicate that this may not be the case. Although the overall neonatal outcome in the postdate pregnancies was good, the increased
147
rates, in this group, of macrosomia, fetal distress and meconium in labor may have a potentially adverse effect on both mothers and neonates. A recent review on postdate pregnanciesanalyzed 11 randomized, controlled trials comparing a policy of induction of labor with a policy of expectant managementand serial fetal surveillance [9]. Meta-analysis of these trials shows that induced labor groups are less likely to have fetal distress, meconium-stained amniotic fluid, macrosomic babies and babies who die during the perinatal period. Women who undergo induction of labor are also lesslikely to undergo delivery by cesarean section or operative vaginal delivery [9]. In accord with these conclusions, the results of the present study demonstrate that despite very early fetal surveillance starting at 40 completed weeks of gestation, there is still a higher incidence of cesarean sections, operative deliveries, heavy babies and meconium. References [I] McClure-Browne JC. Postmaturity. Am J Obstet Gynecol 1963;85: 573-582. [2] Arias F. Predictability of complications associatedwith prolongation of pregnancy. Obstet Gynecol 1987; 70: 101-106. [3] Grauz JP, Heimler R. Asphyxia and gestational age. Obstet Gynecol 1983;62: 175-179. [4] Bochner CJ, Williams III J, CastroL, Medearis A, Hobel CJ, Wade M. The efficacy of starting postterm antenatal testing at 41 weeks as compared with 42 weeks of gestational age. Am J Obstet Gynecol 1988; 159: 550-554. [5] Guidetti DA, Divon MY, Langer 0. Postdate fetal surveillance: is 41 weeks too early? Am J Obstet Gynecol 1989; 161: 91-93. 161Barss VA, Frigoletto FD, Diamond F. Stillbirth after nonstresstesting. Obstet Gynecol 1985;65: 541-544. [7] Clement D, Schifrin BS, Kates RB. Acute oligohydramnios in postdate pregnancy. Am J Obstet Gynecol 1987; 157: 884-886. (81Grubb DK, Rabello YA, Paul RH. Post-term pregnancy: fetal death rate with antepartum surveillance. Obstet Gynecol 1992;79: 1024-1026. [9] Hannah ME. Postterm pregnancy: should all women have labour induced? A review of the literature. Fetal Mater Med Rev 1993;5: 3-17.