Macrosomic infants are not all equal

To see whether macrosomic infants have different morbidity according to maternal screening results for gestational diabetes mellitus (GDM) and ethnicity.

After excluding infants of women with diabetes, the National Women's Hospital database identified 134 infants who were delivered in 2003 and weighed >or= 4500 g. Case notes were reviewed to record risk factors for macrosomia, delivery details and neonatal morbidity. Outcomes were analysed according to screening results for GDM and compared between Polynesian and Asian women.

Body mass index (BMI) was calculated in 29% of women, and GDM screening was undertaken in 51%. Infants of women who had a screening glucose < 7.2 mmol/L compared to >or= 7.8 mmol/L had lower rates of admission to the neonatal intensive care unit (NICU) (6.4 vs 28.6%, P=0.049), had less respiratory distress (3.2 vs 23.8%P=0.033) and display a trend to less require intravenous dextrose (6.4 vs 23.8%P=0.10). Maternal BMI was lower in Asian (26.5 +/- 4.4 kg/m(2)) compared to Polynesian women (35.2 +/- 8.1 kg/m(2), P=0.008). More Asian women had a Caesarean delivery (73.3 vs 25%P<0.001) and their infants were more likely to be admitted to NICU (33.3 vs 7.7%P=0.02), require intravenous dextrose (20 vs 1.9%P=0.03) and have respiratory distress (26.7 vs 3.8%P=0.02).

Risk factors for macrosomia are not assessed adequately, which may contribute to morbidity. Using a birthweight >or= 4500 g to define macrosomia is associated with disparate morbidity between ethnicities that have different body compositions.