Recurrence of gestational diabetes: pregnancy outcome and birth weight diversity

OBJECTIVE: We sought to evaluate birth weight diversity and pregnancy outcome in women with two consecutive pregnancies complicated with gestational diabetes mellitus (GDM). METHODS: 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. RESULTS: 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. CONCLUSION: In GDM patients, owing to the role of glycemic control and environmental factors, an expected increase in birth weight between pregnancies cannot be predicted.