Is Gestational Weight Gain below That Recommended by IOM for Obese Women with Insulin Treated Gestational Diabetes Safe?

The Institute of Medicine (IOM) recommends gestational weight gain (GWG) of 5-9 kg in women with a body mass index of >/=30. Debate continues as to whether GWG less than that recommended is safe. Concern relates to whether this would result in an increase in small for gestational age (SGA) infants, or an increase in rates of prematurity. We examined pregnancy outcomes for mothers with a BMI >/=30 and their offspring in 473 women. All women recorded on our Atlantic DIP database with a singleton pregnancy treated with insulin and a BMI>/=30 were included. Women were categorised into 3 groups as follows (1) those with weight loss, N = 97 (2) weight gain 0-5kg, N = 49 (3) weight gain >5kg N = 327, from first antenatal visit to delivery. Rates of maternal outcomes (pregnancy induced hypertension (PIH), preeclampsia (PET), antepartum (APH) and postpartum haemorrhage (PPH), week of delivery, caesarean section (CS) delivery) and neonatal outcomes (birth weight, large for gestational age (LGA), SGA, macrosomia, prematurity, neonatal morbidities) were compared. Mean maternal booking BMI was 38, 37.6 and 36 kg/m² (p<0.01) and mean maternal age was 34.7, 34.1 and 33.3 years in groups 1,2 and 3 respectively (p=0.04). Rates of PIH PET APH PPH and CS were similar between groups. Glycaemic control prior to delivery was better in women in group 1 compared to groups 2 and 3 (HbA1C 37.2 vs. 38.4 vs. 39 mmol/mol; p = 0.02). Infant birth weight was lower in group 1 compared to groups 2 and 3 (3545g vs. 3645g vs. 3703g; p<0.01) Rates of LGA, macrosomia. SGA and prematurity (<37 gestational weeks) were similar between groups. Rates of neonatal hypoglycaemia were less in group 1 compared to groups 2 and 3; (2.1% vs. 14.3% vs. 4%; p<0.01), while all other morbidities were similar between groups. Gestational weight change for GDM women treated with insulin below that recommended by the IOM appears safe. In addition, it is associated with better maternal glycaemic control and lower infant birth weight.