"An amniotic fluid index<or =5 cm within 7 days of delivery in the third trimester is not associated with decreasing umbilical arterial pH and base excess." - GreenMedInfo Summary

OBJECTIVE: To determine if an amniotic fluid index (AFI)

STUDY DESIGN: Cases for this retrospective cohort study were all pregnancies>or =26 weeks with intact membranes and an AFI5.0 cm within 7 days of delivery were matched to each case within 1 week by gestational age. For a control group with a mean+/-SD umbilical arterial pH of 7.26+/-0.07 and alpha=0.05, a sample size of 100 would have a power of 99% to detect a difference with a study group whose mean was 7.20. Data were compared using paired Student's t-test, Mann-Whitney, Fisher's exact, chi(2) and risk ratios with 95% confidence intervals.

RESULTS: In all, 131 neonates with an AFI5 cm. There was no difference in gestational age (37.6+/-3.0, 37.7+/-3.0 weeks) or birth weight (2897+/-810, 2762+/-788 g). There was no difference in umbilical artery pH (7.25+/-0.07, 7.26+/-0.07) or base excess (-3.32+/-2.59, -2.83+/-2.45 mmol/l), even in small for gestational age (SGA) infants in both groups. There was no difference in the number of SGA neonates, 5-minute Apgar<7, respiratory distress syndrome, necrotizing enterocolitis, or neurologic morbidity. Linear regression showed no correlation between AFI and either umbilical arterial pH (r=-0.00047, SE=0.001, p=0.63) or base excess (r=-0.029, SE=0.037, p=0.428).

CONCLUSION: An AFI