Amniotic fluid index in normal pregnancy: an assessment of gestation specific reference values among Indian women.

Aim: To obtain a gestational reference range for the amniotic fluid index (AFI) among Indian women.

Methods: An analysis of AFI estimations was undertaken in 517 Indian women with normal pregnancy between 16 and 42 weeks of gestation. It was a prospective, cross-sectional study conducted in a university teaching hospital. Women with fetal anomalies, pregnancy-induced hypertension, diabetes mellitus, and other maternal complications were excluded from the study. The median, the 5th and the 95th percentile values were calculated for each gestational week and these values were compared with other studies.

Results: The median reached its peak at the 27th week of gestation. We observed approximately 6 cm as the lower limit of normal (5th percentile) and approximately 18 cm (95th percentile) as upper limit of normal AFI at term for our population, whereas in the Caucasian population, the values were approximately 7 cm and approximately 20 cm, respectively. All gestation specific AFI values were lower in the studied population of Indian women compared with other studies on Caucasian population (P < 0.01 for 5th percentile & P < 3.26 x 10(-7) for 95th percentile), but slightly higher than the Chinese population.

Conclusion: Amniotic fluid index values differ in different populations. We standardized the reference values for normal AFI in Indian women. We found that they are lower in the population studied compared with reported values in the Caucasian population, but slightly higher than the Chinese population.