Towards normalized birthweight in gestational diabetes mellitus

The objective was to describe pregnancy outcomes in gestational diabetes mellitus (GDM) in comparison with general population in Sweden.

A population-based retrospective study using University hospital records and Swedish Medical Birth Register was carried out on pregnant women with well-monitored GDM (n = 870) and pregnancies in the Swedish Medical Birth Register (n = 1 553 420). Data from GDM pregnancies was compared to pregnancies in the whole of Sweden during 1995-2010. The main outcome measures were age, first bodyweight in and weight gain during pregnancy, birthweight, gestational length, percentage of cesarean deliveries.

First maternal bodyweight during the GDM pregnancy was higher than in the general population, 72.4 ± 17.4 kg (n = 837) vs. 67.3 ± 12.6 kg (n = 1 383 000; p < 0.0001). Women with GDM gained less weight during pregnancy 9.9 ± 5.8 kg (n = 703) compared to the general population, 13.2 ± 5.7 kg (n = 482 860; p < 0.0001). Mean birthweight in GDM pregnancies was 3564 ± 500 g (n = 743) compared to 3580 ± 483 g for the general population (n = 1 316 364; p = ns). Gestational length was slightly shorter, 39.4 weeks in the GDM pregnancies (n = 683) vs. 39.5 weeks (n = 1 319 876; p = 0.02) in the general population and the percentage of cesarean deliveries higher in the GDM pregnancies at 18.4% (n = 712) vs. 13.3% (n = 1 322 242; p < 0.0001).

Though many studies have shown an increased risk of macrosomia in GDM pregnancies, remaining even after ambitious management programs, we show no difference in birthweight. This may be due to a combination of intense efforts to achieve good metabolic control during pregnancy and shorter pregnancy duration. Preventing unduly large babies is crucial to minimize adverse pregnancy outcomes.