Amniotic Fluid Index and Birth Weight: is There a Relationship in Diabetics with Poor Glycemic Control?

Objective: This study was undertaken to evaluate if the previously demonstrated relationship between macrosomia (> 4000 g) and polyhydramnios (> 25 cm) is linear across birth weights (BW) in diabetic patients with poor glycemic control.

Study Design: Using a prospectively collected database of patients undergoing amniocentesis for fetal lung maturity for various indications with amniotic fluid index (AFI) obtained < or = 7 days before delivery and BWs available (n = 69), we computed gestational age (GA) specific AFI and BW centiles using standard tables. BW and AFI centiles were analyzed in diabetic patients with poor glycemic control using linear regression and ANOVA, with P < .05 significant.

Results: In the poorly controlled diabetic population, a linear relationship existed between AFI and BW centiles, with the largest BW centiles having the highest AFI centiles (P < .0001).

Conclusion: The previously noted relationship between elevated AFI and BW centiles in the general patient population is linear in diabetic patients with poor glycemic control.