To Örebro University

Objective: To determine if disproportionate body composition is a risk factor for perinatal complications in large-for-gestational-age infants born to mothers with type 1 diabetes.

Design: Population-based cohort study.

Setting: Data from the Swedish Medical Birth Registry from 1998 to 2007.

Population: National cohort of 3517 infants born to mothers with type 1 diabetes. Only singletons with gestational age 32-43 weeks were included.

Methods: Large for gestational age (LGA) was defined as birthweight > 90th centile and appropriate for gestational age (AGA) as birthweight between 10th and 90th centiles. Disproportionate (D) infants were defined as having a ponderal index [PI: calculated as birthweight in grams/(length in cm)(3) > 90th centile] and proportionate (P) as PI ≤ 90th centile. LGA infants were classified as P-LGA or D-LGA. Odds ratios were calculated for D-LGA and P-LGA infants, with AGA infants as the reference category. Odds ratios were adjusted for mode of delivery, fetal distress and stratified by gestational age.

Main outcome measures: The primary outcome was a composite of neonatal morbidities, i.e. any of the following diagnoses: Apgar score < 7 at 5 minutes, birth trauma (Erb's palsy or clavicle fracture), respiratory disorder, hyperbilirubinaemia or hypoglycaemia requiring treatment.

Results: Composite morbidity was significantly more frequent in LGA as opposed to AGA infants, but there was no difference in risk between P-LGA and D-LGA infants.

Conclusions: High birthweight, irrespective of body proportionality, is a risk factor for neonatal complications in offspring of women with type 1 diabetes.