Ultrasonographic Assessment of Normal Amniotic Fluid Index in a Group of Iranian Women

Background/ The objective of this study was to determine the normal values of amniotic fluid index (AFI) at different gestational ages among a group of Iranian women.Patients and The four-quadrant sum of amniotic fluid pockets, AFI, was studied in 489 normal pregnant women with 20-42 weeks of gestational age. Those with diabetes mellitus, hypertension, ultrasonographically detectable anomalies, premature rupture of membranes, intra-uterine growth retardation, and any known fetal abnormalities were excluded from the study. The mean 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles of AFI for each gestational age were calculated. The mean±(±SD) gestational age of the pregnant women studied was 31.46±6.1 (range: 20-41) weeks. The mean±(±SD) AFI was 13.26±4.59 (range: 5.1-26.1) cm. The mean (±SD) AFI was 12.1±1.6 cm (Confidence Interval 95%: 8.9-15.3) at the 20th week, increased to 14.6±1.2 cm (CI95%: 12.2-17) at the 27th week, which then declined to 10.9±1.2 (CI95%: 8.5-13.3) at the 41st week. Our study determined the curve of normal values of AFI for each gestational age and the upper and lower normal limits in a group of Iranian women.