How safely can post-term pregnancies with uncertain gestational age be followed up using amniotic fluid index measurements?

Abstract

Objective. To review whether 2 weeks’ follow-up is safe for women at 42 weeks with an uncertain gestational age (GA) and amniotic fluid index (AFI) of ≥10 cm, as well as reassuring cardiotocography (CTG).
Methods. A retrospective descriptive study of women with an uncertain GA of 42 weeks was done at Tygerberg Hospital. The women had weekly CTG and AFI determinations. Induction of labour followed non-reassuring CTG or an AFI of <5.
Results. A total of 135 women were studied. The time interval between first evaluation at uncertain 42 weeks and delivery ranged between 0 and 46 days (median 10 days). Of the women, 104 had normal vaginal deliveries and 31 (23.0%) caesarean sections. Eleven women (8.1%) with an AFI ≥10 had CS for fetal distress within 2 weeks of the visit at 42 weeks. No neonatal morbidity or mortality was noted.
Conclusion. Weekly monitoring with CTG and AFI at 42 weeks with unsure GA is safe. A follow-up visit after 2 weeks cannot be recommended, as 8% of women required CS within less than 2 weeks because of fetal distress.