Maternal obesity is a well established risk factor for gestational diabetes but it is not known if the pattern of maternal fat distribution predicts adverse pregnancy outcomes.

Body composition was assessed by bioimpedance using Inbody 720® in 302 consecutive obese pregnant women attending a weight management clinic. The relation of visceral fat mass and total percentage body fat with the development of gestational diabetes and perinatal outcomes was evaluated.

Women developing gestational diabetes (Group 1; n = 72) were older, had higher body mass indices and greater central obesity (waist:hip ratio, visceral fat mass) compared with those remaining normoglycaemic. Visceral fat mass, but not percentage body fat, correlated with fasting glucose in all patients (r = 0.2, p < 0.001) and particularly those in Group 1 (r = 0.35, p = 0.002). Visceral fat mass, but not percentage body fat, also correlated strongly with glycaemia, particularly in Group 1 (r = 0.47, p < 0.0001). Visceral fat mass also showed a weak but significant correlation with baby weight (r = 0.17, p = 0.01).

Central obesity, as assessed by early pregnancy waist:hip ratio and particularly by visceral fat mass, is a predictor of gestational diabetes in addition to classical risk factors and may help identify those obese patients at increased risk of complications.