Serial antenatal monitoring compared with labor induction in post-term pregnancies

In view of the increased risk of obstetric and perinatal complications in post-term pregnancy, and the lack of consensus regarding clinical routines for fetal surveillance and labor induction, the aim of this prospective controlled study was to compare obstetric and perinatal outcome after serial monitoring until 43 weeks of gestation with that after labor induction at 42 gestational weeks.

A study group of 193 gravidae scheduled for serial monitoring until 43 weeks of gestation was compared with a control group of 205 gravidae admitted for induction of labor at 42 weeks. A third, high-risk, group comprised gravidae (from either of the foregoing groups) who had to be admitted for emergency induction of labor owing to increased fetal risk (i.e., the presence of oligohydramnios or a small-for-gestational-age fetus).

The frequency of labor induction was significantly lower in the study group than among controls (p < 0.001), but the two groups did not differ in obstetric or perinatal outcome. As compared with these two low-risk groups, the high-risk group was characterized by significantly higher frequencies of instrumental delivery (p < 0.01), operative delivery for fetal distress (p < 0.001) and infants requiring neonatal intensive care (p < 0.001).

As the wait-and-see policy with serial monitoring resulted in a lower rate of labor induction, but not in a lower rate of instrumental delivery or perinatal complication, medically the two routines would appear to be comparable. However, an individual approach with intensified fetal surveillance is to be recommended, as it is vital to identify post-term pregnancies where the fetus is at increased risk. The use of such new techniques as umbilical artery flow velocimetry would no doubt improve the management of high-risk post-term pregnancies.