3.1. Sample Size Estimation. Khadilkar et al. [16] from the Department of Obstetrics and Gynaecology, Grant Medical College, Mumbai, conducted a prospective, cross sectional study in low risk healthy pregnant subjects to obtain a gestational reference range for AFI among Indian women.They noted that the mean and standard deviation of AFI (cm) at 34 weeks of gestation was 14.2 and 2.4, respectively.We hypothesised that a difference of 1.5 cmin themeanAFIwould be significantly different from the normal values and accordingly estimated sample size to show a desired level of power of 90% and level of significance 0.05, by using the formula,