Introduction Fetal growth abnormalities are common complications of diabetes in pregnancy; there is little data on temporal trends in growth disturbance.

Aim To determine changes in rate of large for gestational age (LGA) and small for gestational age (SGA) in babies of women with pre-gestational Type 1 or Type 2 diabetes (T1DM and T2DM).

Methods Data were extracted from the Northern Diabetes in Pregnancy Survey, a register of pregnancies in women with pre-gestational diabetes resident in Northern England. We studied 1499 singleton live births delivered 1996–2008, excluding those with congenital anomalies. LGA was defined as birtweight >90th percentile for gestational age and SGA as<10th percentile, corrected for infant sex and parity.

Results 1164 (78%) women had T1DM and 328 (22%) T2DM; T2DM increased from 8.9% (1996–2000) to 32.1% (2005–2008) (p=0.01). Mean (SD) birth weight was 3437 g (±755). 335 (23%) babies weighed ≥4000 g. The rate of LGA was 49.3% and SGA 2.9% and did not change over time (LGA 50.9%, 1996–2000, 47.7%, 2005–2008; SGA 3.5%, 1996–2000, 2.9%, 2005–2008; p=0.73). LGA babies were more likely to be preterm (60.3% vs 37.2%, p=0.001), delivered by caesarean section (53.5% vs 43.3%, p=0.001), admitted to special care (56.5% vs 40.7%, p=0.001) and to develop shoulder dystocia (85.7% vs 11.9%, p= 0.001) than babies of normal weight for gestational age.

Conclusion Rates of LGA and SGA have not changed over time despite an increase in T2DM.