Objective: To assess the usefulness of amniotic fluid index (AFI) in the assessment of postdate pregnancies.
Study design: A prospective, observational study was carried out on the AFI of 118 well-dated postdate pregnancies at 41 weeks within 2 days of delivery. The AFI quartile distribution was determined and correlated with the risk of thick meconium-stained liquor (MSL), intervention for fetal distress and admission to the special care baby unit (SCBU).
Results: The median AFI was 8 cm, with a range from 1-33 cm. There was a significant inverse correlation between the occurrence of thick MSL, intervention for fetal distress and SCBU admission. Logistic regression analysis, upon adjusting for possible confounding factors, showed that only AFI in the 2 lower quartiles combined (< or = 8 cm) had a significant association with the risk of thick MSL (adjusted OR 11.0, 95th CI 2.43-49.8) but not admission to the SCBU. AFI in the lowest quartile (< or = 5 cm) had a significant association with the risk of intervention for fetal distress only (adjusted OR 7.95, 95th CI 1.67-37.7).
Conclusion: Although AFI may be used to predict the occurrence of thick MSL and the need for intervention for fetal distress in postdate pregnancies, its role on its own is limited.