AIMS: To evaluate fetal growth in relation to gestational weight gain in women with Type 2 diabetes.

METHODS: A retrospective cohort study of 142 consecutive pregnancies in 28 women of normal weight, 39 overweight women and 75 obese women with Type 2 diabetes (pre-pregnancy BMI < 25, 25-29.9, ≥ 30 kg/m2, respectively). Gestational weight gain was categorized as excessive (exceeding the US Institute of Medicine recommendations) or as non-excessive (within or below the Institute of Medicine recommendations).

RESULTS: Excessive and non-excessive gestational weight gain were seen in 61 (43%) and 81 women (57%) with a median (range) gestational weight gain of 14.3 (9-32) vs. 7.0 (-5-16) kg (P < 0.001), respectively. Infants of women with excessive gestational weight gain were characterized by higher birth weight (3712 vs. 3258 g; P = 0.001), birth weight z-score (1.14 vs. -0.01, P = 0.001) and prevalence of large-for-gestational-age infants (48 vs. 20%; P < 0.001). In normal weight, overweight and obese women with non-excessive gestational weight gain, the median weight gain in the first half of pregnancy was 371, 114 and 81 g/week, and in the second half of pregnancy 483, 427 and 439 g/week, respectively. In multiple linear regression analysis, gestational weight gain was associated with a higher infant birth weight z-score independent of pre-pregnancy BMI, smoking, HbA1c and insulin dose at last visit, ethnicity and parity [β=0.1 (95% CI 0.06-0.14), P < 0.001].

CONCLUSIONS: Infant birth weight was almost 0.5 kg higher in women with Type 2 diabetes and excessive gestational weight gain than in women with Type 2 diabetes and non-excessive weight gain.