Obstetric outcome in uncomplicated prolonged pregnancy

lltwutitul JourNl01

GYNECOLOGY &OBSTETRICS International Journal of Gynecology & Obstetrics 55 (1996) 225-230

Article

Obstetric outcome in uncomplicated prolonged pregnancy Z.M. Abotalib, M.H. Soltan*, N. Chowdhury, B. Adelusi Department

of Obstetrics

& Gynaecology,

King Khalid University Saudi Arabia

College of Medicine,

King Saud Uniuersity,

Riyadh,

Received 24 April 1996; revised 18 July 1996; accepted 29 July 1996

Abstract Objective: To study and compare the obstetric outcome in term pregnancies and uncomplicated prolonged Methods: The study was a retrospective review of 596 cases. The case notes of 286 patients with pregnancies. uncomplicated prolonged pregnancies (2 42 weeks) and 310 patients with normal term pregnancies (37 to < 42 weeks) were analyzed. The Gold Stat package was used for statistical coding and analysis. Results: There was no fetal morbidity or mortality among the two groups. However, the number of previous abortions were significantly higher in prolonged pregnancies compared with term pregnancies. Similarly, fetal and placental weights, labor induction and operative delivery rates were significantly higher in prolonged pregnancies. However, there were no significant differences between the patients who were induced and those who had spontaneous labor among the prolonged pregnancies. Conclusions: There is no doubt that prolonged pregnancy may be associated with certain risks factors, However, there is no outcome variable to justify whether or not to induce those pregnancies which are prolonged. Copyright 0 1996 International Federation of Gynecology and Obstetrics.

Keywords:

Prolonged

pregnancy;

Outcome

1. Introduction

The definition of post-term pregnancy varies from institution to institution, as term pregnancy varies from place to place, and may even vary according to race [l]. The WHO definition of term pregnancy of 294 days [2] is universally accepted. However, the fact that one in 20 pregnant women fail to go into spontaneous labor after this

*Corresponding

author. Fax: + 966 I 467-1993.

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period of gestation attests to the wide variation in gestational length [3]. Furthermore, approximately 10% of all pregnancies last longer than 42 weeks, although, this figure is halved if gestation is based on accurate menstrual dates or early ultrasonic examination [4]. The argument is further supported by the lack of a detailed knowledge of initiation of labor. It is not known, for example, why some women go into premature labor, while others have prolonged pregnancy. It is known, however, that when pregnancy exceeds 42 weeks’ gestation, perinatal

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mortality is increased [5]. For example, gestationspecific perinatal mortality rates for a Swedish population have been shown to increase from 2-3/1000 at 40 weeks to 4/1000 at 43 weeks [5]. There is an ongoing debate on whether or not induction of labor for prolonged pregnancy could result in a better obstetric outcome. The reluctance of some practitioners to support a routine induction policy has stemmed from a belief that such a policy would result in increased operativedelivery, and hence, increased maternal morbidity. Aside from perinatal mortality, the fetal morbidity associated with prolonged pregnancy has been reiterated in a recent editorial by Rosen and Dickenson [6]. They stated that after 42 weeks’ gestation, about 2.8% of fetuses exceed 4500 g at delivery, compared with only 0.8% at 40 weeks. In addition, there may be the attendant risks of shoulder dystocia, brachial plexus injury, maternal soft tissue injury, and the fetus may outgrow its placental supply and suffer from placental insufficiency and thereby be at an increased risk of meconium aspiration in utero [7]. However reports have shown that routine induction at 42 weeks does not appear to improve neonatal outcome [8-101. The objective of the present study was to determine the outcome of pregnancy in post-term cases, when compared with term cases, as well as when post-term pregnancies are induced. 2. Materials

and methods

The delivery log and computerized database of the obstetric unit of the KKUH were reviewed over the period January 1994 to December 1994. During this study period, there were 4512 deliveries in the unit, of which 286 normal patients having had an uncomplicated prolonged pregnancy (42 weeks and above) were selected. All abnormal pregnancies such as women with diabetes, pre-eclampsia, IUGR, hypertension and were excluded from the other abnormalities study. Case files of 310 women with normal pregnancies from 37 completed weeks to 41 weeks of gestation were randomly selected and reviewed to serve as controls. The controls were each selected within 24 h of delivery of each case study.

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A comprehensive review of the maternal charts of all cases and controls was undertaken. Gestational age was confirmed from the prenatal records, using information regarding the accuracy of the women’s last normal menstrual period. It was further confirmed by ultrasound bi-parietal diameter results which were obtained prior to 20 weeks, or crown-rump length which was obtained between 6 and 14 weeks. All unresolved dating discrepancies were excluded from the study. Those patients allowed to go beyond term were monitored with daily kick charts, twice weekly nonstress tests and weekly biophysical profiles, and all those with abnormal tests were excluded. Among the outcome variables, fetal distress was defined as the presence of moderate to severe variable decelerations in labor, fetal bradycardia or tachycardia requiring operative intervention, decreased fetal heart rate variability, and meconium-stained amniotic fluid necessitating delivery. Neonatal morbidity was defined as the presence of birth trauma, including cephalhematoma, clavicular fracture and brachial plexus injury, admission to the neonatal intensive care unit for hyperbilirubinemia with or without the need of phototherapy, among others. The data were collated and analyzed, using the Gold Stat package. Chi-square test and other descriptive statistics were used to obtain the statistical significance for different variables. 3. Results

There was no fetal mortality during the study period. Maternal and fetal morbidity was also very low. Cases of fetal distress and meconium stained fluid were observed in 5.3% and 2.5%, respectively among the study groups, and 2.6% and 1.3%, respectively in the controls. Postpartum hemorrhage occurred in 1.4% among the study group and 1.6% in the controls. NICU admission was low in both groups. Table 1 shows the demographic characteristics of patients with post-term pregnancies and control. There was no significant difference between the two groups with regard to age and parity. However, the number of patients with three or

Z.M. Table 1 Demographic

characteristics

Abotalib

et al. /International

of patients

with

post-term

Controls Age (years) 15-25 26-34 35 + Parity 0 1-4 5+ History of abortion l-2 3+ “Statistically

significant

Journal

pregnancies

2 characteristics

Onset Spontaneous Induced Duration fmin) < 480 480-720 > 720 Mode of delivery Spontaneous Forceps Vacuum cs x Statistically

significant

& Obstetrics

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227

225-230

and controls Cases (%o)

(%c)

f-value

119 (52.4) 153 (52.2) 38 (50.0)

108 (47.6) 140 (47.8) 38 (50.0)

0.87 0.92 0.79

48 (46.6) 201 (53.3) 61 (53.0)

55 (53.4) 177 (46.7) 54 (47.0)

0.23 0.46 0.81

84 (48.8) 7 (25.0)

88 (51.2) 21 (75.0)

0.32 0.003*

at 5% level of significance.

more abortions were significantly higher among the study cases (P = 0.003). The induction rate was much higher (72.7%) in the cases with prolonged pregnancy, as compared with 27.3% in the controls. (Table 2). This difference was statistically significant (P < 0.001). Similarly, instrumental deliveries, particularly vacuum delivery, and cesarean section rates, were significantly higher in the cases, compared with controls (P = 0.02 and 0.011, respectively. There were no statistically significant differences however, between the two groups in terms of duration of labor. There were differences in mean placental weights as well as mean fetal weights between the Table Labor

of Gynecology

of patients

with

post-term

pregnancies

cases and controls (Table 3). The study cases tended to show statistically significant heavier placental and fetal weights 0’ = 0.004 and < 0.001, respectively). However, there were no significant differences found in the duration of labor, requirements for analgesia and Apgar score between the cases and controls. Table 4 shows that there was no significant difference in duration of labor or mode of delivery, except for instrumental delivery (vacuum) among the prolonged pregnancy patients who went into spontaneous labor compared with those amongst them who had their labor induced. The difference in vacuum delivery was statistically significant, however (P < 0.03).

and controls

t 42

< 42 Weeks

f-value

134 (34.6%) 152 (72.7%)

253 (65.4%) 57 (27.3%)

< 0.001” < 0.001*

187 (50.8%) 59 (42.1%) 40 (45.5%)

181 (49.2%) 81 (57.9%) 48 (54.5%)

0.08 0.11 0.61

243 (46.2%) 2 (20.0%) 15 (71.4%) 26 (66.7%)

283 8 6 13

0.01* 0.07 0.02* 0.01”

at 5% level of significance

(53.8%) (80.0%) (28.6%) (33.3%)

228 Table Mean

2.M. 3 values

of labor

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et al. /International

in patients

Journal

with

of Gynecology

post-term

pregnancies

& Obstetrics

*Statistically

significant

27.46 2.67 0.42 4.41 475.12 443.71 106.19 25.00 627.07 3294.84 7.66 8.98

i f + f f f f * + & f +

5.5 2.2 0.78 1.5 265.39 327.21 27.66 0.0 124.2 443.36 1.09 0.46

4 characteristics

of post-term

patients

Characteristics

5 values

who had induced

or spontaneous

27.63 2.73 0.65 4.83 426.64 457.94 103.05 25.25 657.29 3492.24 7.55 8.94

0.71 0.73 O.OOS* 0.13 0.08 0.77 0.28 0.46 < o.otM* < 0.001* 0.28 0.59

f k * * f + * f + k * f

5.3 2.4 1.3 1.8 254.16 295.42 17.3 2.5 113.94 413.36 1.3 1.2

116 2 3 13

of demographic

and labor

with analgesia

Total

97 (52.2%) 31 (51.7%) 24 (60%)

(47.7%) (100.0%) (20.0%) (50.0%)

characteristics

127 0 12 13

for spontaneous

Spontaneous (mean A S.D.)

Age

labor Induced

89 (47.8%) 29 (48.3%) 16 (40%)

Parity Abortion Number of patients Placenta weight Fetal weight Apgar 1 min Apgar 5 min

P-value

had induced labor were compared with those who had spontaneous labor (Table 5). Even though the grandmultiparous patients tended to go into

Spontaneous

Duration (min) < 480 480-720 > 720 Type of delivery SVD Forceps Vacuum cs

Table Mean labor

2 42 Weeks cases (mean k SD.)

at 5% level of significance.

There was no significant difference found in relation to the mean demographic and labor characteristics, when prolonged pregnancy cases who Table Labor

225-230

and controls

< 42 Weeks controls (mean + S.D.) Age Parity Previous history of abortion Bishop score Duration spontaneous labor (min) Duration induced labor (min) Number of patients taking 1 analgesia Number of patients taking > 2 analgesia Placental weight Fetal weight Apgar 1 min Apgar 5 min

55 (1996)

27.57 2.99 0.66 102.08 664.83 3513.01 7.64 9.05

f + + + f f 5 rf:

5.8 2.7 1.41 14.1 119.66 408.77 0.99 1.02

0.64 0.79 0.35

(52.3%) (0%) (80.0%) (50.0%)

in post-term

0.48 0.13 0.03* 0.74

pregnancies

who

had induced

or spontaneous

Induced (mean + S.D.)

P-value

27.68 2.51 0.64 103.61 650.70 3473.93 7.47 8.84

0.86 0.10 0.94 0.62 0.32 0.43 0.27 0.15

k f + f f + + *

4.9 2.2 1.14 18.8 3.05 417.9 1.5 1.39

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spontaneous labor, this difference was not statistically significant. 4. Discussion

Prolonged pregnancy has always been regarded as a high risk condition. Indeed, several studies over the last 60 years have shown that perinatal mortality and morbidity tend to rise when pregnancy goes beyond 42 weeks [ll-141. In contrast however, the present study has not shown any increased perinatal mortality and morbidity. In an interview-based study [l], using multiple linear regression to analyze 9355 observations at the Boston Hospital for women from 1977-1980, 140 variables were evaluated in terms of predicting prolonged pregnancy. The results showed that multiparous women, women aged < 19 or > 34 years, and black women had shorter gestations compared with primipara, women aged 19-34 years, and Caucasian women, respectively. However, there was no significant difference in age and parity in the present study, although a significant association was found between prolonged pregnancy and a history of three or more abortions (P = 0.008). Therefore there may be a need to review the predictive value of abortions on prolongation of pregnancy, in order to anticipate this problem in recurrent aborters. A statistically significant difference was observed in the mode of delivery when patients with prolonged pregnancy were compared with controls. Our findings are in concordance with the findings of Votta and Cibils [4] who had also observed an increased incidence of cesarean section and instrumental deliveries in the post-term group. However, as Steel [15] stated in his commentary, there may be much ado about nothing concerning post maturity. He advocated, therefore, that as most babies continue to grow significantly, the pregnancies should be allowed to continue, unless growth retardation can be demonstrated. This current study is in support of this viewpoint. The mean placental weight as well as fetal weight, for example, were significantly higher in the study cases, compared with the controls (P < O.OOl), thus demonstrating continued fetal growth beyond term.

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Knox et al. [lo] studied 180 women at 42 weeks’ gestation randomly assigned to two groups with high and low induction. There was no difference in the outcome, as measured by the occurrence of fetal distress in labor, or Apgar scores. The current study is in agreement with these findings, as there were no significant differences in fetal distress and Apgar scores when prolonged pregnancy cases who were induced were compared with those of them who had spontaneous labor. Similarly, there was no significant difference in the need for analgesia in post-term cases who had spontaneous labor compared with those who were induced. There is no doubt that prolonged pregnancy may be associated with increased risks of operative deliveries and bigger than average babies, compared with controls. However, when it comes to the question of whether or not to induce these patients, there is no outcome variable which would give any justification for one course of action over the other, as shown in our results. As long as the various parameters of ultrasound, non-stress test, fetal kicks, and biophysical profile, all remain within normal limits, induction of labor may not therefore be necessary. References

[II

PI [31 [41

[51

[61

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