Background
Antenatal ultrasound is used frequently in pregnancies complicated by hyperglycaemia; however, it is unclear which measurements have the greatest association with adverse neonatal outcomes.

Aim
To assess the association between third trimester ultrasound parameters with adverse neonatal outcomes in pregnancies complicated by hyperglycaemia.

Method
All pregnant women with gestational or type 2 diabetes who birthed in a regional hospital over 12 months were included. A composite adverse neonatal outcome was defined by one or more: admission to special care nursery, acidosis, hypoglycaemia, jaundice, shoulder dystocia, respiratory distress syndrome or 5‐minute Apgar score < 5. Logistic regression was used to determine odds ratios (OR) for an adverse neonatal outcome, according to pre‐specified cut points in both lower and upper percentiles of abdominal circumference (AC) and estimated fetal weight (EFW). Results Of 275 births an adverse outcome occurred in 122 (44%). Unadjusted OR (95% CI) for AC ≤30th was 3.2 (1.1–8.8) and >95th percentile was 3.1 (1.5–6.0) compared with the reference group of 31–70th percentile. Unadjusted OR for EFW ≤30th was 1.5 (0.7–3.1) and >95th percentile was 3.0 (1.4–6.3). After adjusting for maternal age, body mass index, diabetes type, ethnicity, gravidity, mode of delivery and gestation at birth the OR (95% CI) were as follows: AC ≤30th percentile, 3.7 (1.1–12.4); AC >95th, 2.2 (1.1–4.8); EFW ≤30th, 2.6 (1.1–6.1); EFW >95th, 2.5 (1.1–6.1).

Conclusion
An AC and EFW up to the 30th percentile may pose just as great a risk to the fetus as an AC or EFW >95th percentile in pregnancies complicated by hyperglycaemia.