Postdate antenatal testing.

OBJECTIVE

To test the effect on pregnancy outcome of a policy of very early commencement of postdate surveillance testing, and induction of labor at 42 weeks.

METHODS

Retrospective analysis of 2776 consecutive cephalic deliveries at 38-42 weeks of gestation. Management of the postdate pregnancies included twice-weekly antenatal testing beginning at 40 completed weeks and elective induction of labor at 42 completed weeks. Pregnancy outcome parameters were 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 cesarean section, mainly accounted for by an increased rate of fetal distress and failure to progress in labor. Similarly the rate of instrumental vaginal 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 weeks of gestation.

CONCLUSION

Despite early initiation of fetal surveillance, starting at 40 completed weeks, postdate pregnancies are associated with an increased rate of emergency cesarean section, macrosomia and meconium in labor.