The Impact of Restricted Gestational Weight Gain on Fetal Growth during Dietary Treatment in Women with Gestational Diabetes Mellitus

Aim: To investigate the impact of maternal gestational weight gain during dietary treatment (GWG-diet) on fetal growth in pregnancies complicated by gestational diabetes (GDM).

Material and Methods: A retrospective cohort study of 382 consecutive women diagnosed with GDM <34 weeks and live singleton births in our center in 2011-2017. The women were stratified according to restricted (53%), appropriate (17%) and excessive (31%) weekly GWG-diet (Institute of Medicine guidelines) to estimate compliance to a calorie-restricted diabetes diet (1700 kcal daily). Insulin therapy was initiated according to local clinical guidelines.

Results: Glucose tolerance, HbA1c, GWG before dietary treatment (GWG-before) and fetal abdominal circumference standard deviation (SD) score were comparable across the three GWG-diet groups at referral at 27⁶±5¹ weeks. The women were followed for 10⁰ ±5¹ weeks, 54% received insulin therapy and the average GWG-diet in the three groups was 0 kg, 3 kg and 5 kg, respectively. Women with excessive weekly GWG-diet, also had increasing HbA1c (p=0.014) during dietary treatment and infants with a birth weight SD-score of 0.59 ±1.6, while women with restricted weekly GWG-diet also had decreasing HbA1c (p=0.001) during dietary treatment, and infants with a birth weight SD-score of 0.15 ±1.1, without intrauterine growth restriction. Excessive GWG-diet and late pregnancy HbA1c were predictors of infant birth weight SD-score (p<0.001) after correction for parity, uptake area, pre-pregnancy BMI and insulin therapy.

Conclusion: Restricted GWG-diet was associated with more appropriate fetal growth in women with GDM. GWG-diet and late pregnancy HbA1c were modifiable clinical predictors of infant birth weight SD-score.