Maternal and neonatal outcomes of large for gestational age pregnancies

Objective: To compare maternal and neonatal outcomes of term large for gestational age (LGA) pregnancies and adequate for gestational age (AGA) pregnancies.

Design: Retrospective analysis.

Setting: Large university research medical center.

Population: All term singleton LGA (birthweight ≥ 90th percentile) and AGA pregnancies (birthweight 10.1-89.9th percentile) delivering between 2004 and 2008.

Methods: Data collected included maternal age, gestational age at delivery, mode of delivery, birthweight, fetal sex, and maternal and neonatal complications. Birthweight percentiles were determined according to locally derived gender-specific birthweight tables.

Main outcome measures: Comparisons between LGA and AGA pregnancies and between LGA 90-94.9th, 95-98.9th and ≥ 99th percentile.

Results: The study population comprised 34 685 pregnancies; 3900 neonates matched the definition of term LGA. Maternal age and gestational age at delivery were significantly higher for LGA neonates. Significantly more LGA neonates were born by cesarean section, and significantly more LGA pregnancies were complicated by postpartum hemorrhage (PPH), shoulder dystocia or neonatal hypoglycemia, and had a longer hospitalization period. Maternal and neonatal risks increased as birthweight increased from the 90-94.9th to 95-98.9th to ≥ 99th percentile. Specifically, the risks of shoulder dystocia (odds ratio 2.61, 3.35 and 5.11, respectively), PPH (odds ratio 1.81, 2.12 and 3.92, respectively) and neonatal hypoglycemia (odds ratio 2.53, 3.8 and 5.19, respectively) all increased linearly with birthweight percentile.

Conclusions: Large for gestational age pregnancies are associated with an increased rate of cesarean section, PPH, shoulder dystocia and neonatal hypoglycemia, as well as longer hospitalization. These risks increase as the birth percentile rises. These risks need to be emphasized in pre-delivery counseling.