Do current sonographic curves overdiagnose intrauterine growth restriction in female fetuses?

OBJECTIVE: To evaluate if female fetuses are over diagnosed with intrauterine growth restriction (IL'GR) clue to the current sonographic curves. Male nconates are known to be heavier than females ;it birth, however, while in utero both genders are evaluated with identical sonographic curves. Perhaps the use of gender-neutral curves overdiagnoses female neonales with growth restriction. This sludv evaluated fetuses diagnosed with IUGR in-utero to determine ii a selection bias is present, overrepresentmg female fetuses. STUDY DESIGN: The obstetric sonogram database was used to identih fetuses diagnosed antenatallv with IUGR [< 10th% for gestational age (GA). based on Haddock's curves]. Exclusion criteria included incorrect dating and congenital anomalies {chromosomal and/or structural). Outcome information obtained: GA at deliverv, method of delivery, birthweight, neonatal length, gender. Apgar scores, and neonatal complications. Foi statistical anahsis the prenatal diagnosis of IUGR was compared with the United States National Reference (USNR) foi Fetal Growth. The true and false positive identification of IUGR was calculated. RESULTS: 61 fetuses were diagnosed prenatallv with IUGR between 7/94 and 5/96, of these 21 were male and 40 female. After delivery compared with the USNR gender-specific curves, IS (86%) of the males and 24 (6.59? ) of the females were considered SGA (P = .0008}. Thus, a false positive diagnosis of IUGR was made in 14% of males and 35% of female fetuses. GA at diagnosis (33 ±4 vs 81 ±5 weeks, P = .2), GA at deliven (36 ± 4 vs 34 ± 5 weeks, P = .07), birihweight (2166 ± 809 vs 1759 ± 929 grains, P = .08), and neonaial length (43 ± 6 vs 38 ± 11 cm, P = .1 ) were not significantly different between the female and male neonates. CONCLUSIONS: The sonographic diagnosis of IUGR overrepresenls female fetuses due to the gender-neutral curves. In light of these findings, we advocate the use of geutlei specific prenatal growth curves.