Recurrence of gestational diabetes: pregnancy outcome and birth weight diversity

We sought to evaluate birth weight diversity and pregnancy outcome in women with two consecutive pregnancies complicated with gestational diabetes mellitus (GDM).

A retrospective longitudinal study of 389 patients with two consecutive GDM pregnancies was assessed for pregnancy outcome and fetal weight diversity. Since there is a tendency towards repetition or moderate increase in fetal weight in subsequent non-diabetic pregnancies, consecutive GDM pregnancies were stratified into three categories. They consisted of: an increase in birth weight of more than 250 g between GDM pregnancies for the same gestational age at delivery, and considered significant; an increase in birth weight of more than 100 g but less than 250 g; and a decrease in birth weight in the second GDM pregnancy compared to the index pregnancy. Any change in birth weight of up to 100 g between the two pregnancies was considered comparable.

The mean interval between the two diabetic pregnancies was 3 years. The change in weight above the biologically expected weight was evaluated. In 181/389 (46%), an elevation in birth weight between pregnancies was recorded and from this group only 125/181 (69%) had significant increases in birth weight (> 250 g) with a mean of 531 +/- 49 g. Furthermore, 130/389 (33.4%) had decreased fetal weight between the two pregnancies (mean 373 +/- 31 g). In 78/389 (20.1%), birth weight changes were considered similar (< 100 g). Fasting plasma glucose (FBG) and pre-pregnancy body mass index (BMI) were significantly elevated in the second pregnancy (FBG 97 +/- 15 vs. 102 +/- 4.7 mg/dl; BMI 25.9 +/- 4.7 vs. 27 +/- 6.7 kg/m2, respectively; p = 0.02). No difference was found in the mean maternal weight gain during pregnancy, gestational age at delivery, mean blood glucose, macrosomia or large-for-gestational-age rates. No difference in neonatal outcome (neonatal intensive care unit admission, the need for respiratory support, stillbirth rate or shoulder dystocia) was found between the two pregnancies.

In GDM patients, owing to the role of glycemic control and environmental factors, an expected increase in birth weight between pregnancies cannot be predicted.