Large-for-gestational age and stillbirth: is there a role for antenatal testing?

Objective: To investigate the association between large-for-gestational-age (LGA) pregnancy and stillbirth to determine if the LGA fetus may benefit from antenatal testing with non-stress test or biophysical profile. Methods: This was a retrospective cohort study of singleton pregnancies that were ongoing at 24 weeks' gestation and that had undergone routine second-trimester anatomy ultrasound examination, during the period 1990 to 2009. Pregnancies complicated by fetal anomaly or aneuploidy, those with missing birth weight information and those that were small-for-gestational age were excluded. Appropriate-for-gestational age (AGA) and LGA were defined as birth weight between the 10^th and 90^th percentiles and > 90^th percentile, respectively, according to the Alexander growth standard. The incidence of stillbirth was calculated as the number of stillbirths per 10 000 ongoing pregnancies. Adjusted odds ratios (aOR) with 95% CI for stillbirth in LGA compared with AGA pregnancies were estimated using logistic regression analysis, controlling for pre-existing and gestational diabetes. The incidence and aOR for stillbirth were estimated at 4-week intervals from ≥ 24 to ≥ 40 weeks' gestation. Results: Of 52 749 pregnancies ongoing at 24 weeks, 46 205 (87.6%) were AGA and 6544 (12.4%) were LGA at delivery. The incidence of stillbirth in LGA pregnancies was significantly higher than that in AGA pregnancies from 36 weeks' gestation (26/10 000 vs 7/10 000; aOR, 3.10; 95% CI, 1.68–5.70). When women with diabetes were excluded in stratified analysis, pregnancies complicated by LGA continued to be at increased risk for stillbirth ≥ 36 weeks (18/10 000 vs 7/10 000; OR, 2.63; 95% CI, 1.27–5.43). Conclusion: Pregnancies complicated by LGA are at significantly increased risk for stillbirth at or beyond 36 weeks, independent of maternal diabetes status, and may benefit from antenatal testing.