Significant risk of repeat adverse outcomes in recurrent gestational diabetes pregnancy: a retrospective cohort study

Background: The risk of adverse outcomes in recurrent GDM pregnancy has not been well documented, particularly in women who have already had an adverse outcome. The aim of this study was to compare the risk of recurrent adverse delivery outcome (ADO) or adverse neonatal outcome (ANO) between consecutive gestational diabetes (GDM) pregnancies.

Methods: In this retrospective study of 424 pairs of consecutive ("index" and "subsequent") GDM pregnancies, we compared the risk of ADO (instrumental delivery, emergency Caesarean section) and ANO (large for gestational age (LGA and small for gestational age (SGA)) in women with and without a history of adverse outcome in their index pregnancy.

Results: Subsequent pregnancies had higher rates of elective Caesarean (30.4% vs 17.0%, p < 0.001) and lower rates of instrumental delivery (5% vs 13.9%, p < 0.001), emergency Caesarean (7.1% vs 16.3%, p < 0.001) and vaginal delivery (62.3% vs 66.3%, p = 0.01). Index pregnancy adverse outcome was associated with a higher risk of repeat outcome: RR 3.09 (95%CI:1.30,7.34) for instrumental delivery, RR 2.20 (95%CI:1.06,4.61) for emergency Caesarean, RR 4.55 (95%CI:3.03,6.82) for LGA, and RR 5.01 (95%CI:2.73,9.22) for SGA). The greatest risk factor for subsequent LGA (RR 3.13 (95%CI:2.20,4.47)) or SGA (RR 4.71 (95%CI:2.66,8.36)) was having that outcome in the index pregnancy.

Conclusion: A history of an adverse outcome is a powerful predictor of the same outcome in the subsequent GDM pregnancy. These high-risk women may warrant more directed management over routine GDM care such as altered glucose targets or increased frequency of ultrasound assessment.