The simultaneous occurrence of gestational diabetes and hypertensive disorders of pregnancy affects fetal growth and neonatal morbidity

Background Gestational diabetes (GDM) is associated with an increased risk of hypertensive disorders of pregnancy (HDP), but there are limited data on fetal growth and neonatal outcomes when both conditions are present. Objectives We evaluated the risk of abnormal fetal growth and neonatal morbidity in pregnancies with co-occurrence of GDM and HDP. Study Design In a retrospective study of 47,093 singleton pregnancies, we compared the incidence of appropriate for gestational age birthweight (AGA) in pregnancies affected by GDM alone, HDP alone, or both GDM and HDP (GDM/HDP) to that in pregnancies affected by neither disorder using generalized estimating equations (covariates: maternal age, nulliparity, BMI, insurance type, race, marital status and prenatal care site). Secondary outcomes were large for gestational age birthweight (LGA), small for gestational age birthweight (SGA), and a neonatal morbidity composite outcome (stillbirth, hypoglycemia, hyperbilirubinemia, respiratory distress, encephalopathy, preterm delivery, neonatal death, neonatal intensive care unit admission). Results The median [IQR] birthweight percentile in GDM/HDP (50 [24.0, 78.0], N=179) was similar to unaffected pregnancies (50 [27.0, 73.0], N=35,833). Yet, the absolute rate of AGA was lower for GDM/HDP (78.2% versus 84.9% for unaffected pregnancies). Adjusted analyses showed decreased odds of AGA in GDM/HDP pregnancies compared to unaffected pregnancies (aOR 0.72, 95% confidence interval [0.52, 1.00], P=0.049), and in pregnancies complicated by GDM alone (aOR 0.78 [0.68, 0.89], P<0.001), or HDP alone (aOR 0.73 [0.66, 0.81], P<0.001). The absolute risk of LGA in GDM/HDP pregnancies (14.5%) was greater than in unaffected pregnancies (8.2%) without apparent difference in the risk of SGA (7.3% vs 6.9%). However, in adjusted models comparing GDM/HDP to unaffected pregnancies, neither an association with LGA (aOR 1.33 [0.88, 2.00], P=0.171) nor SGA (aOR 1.32 [0.80, 2.19], P=0.293) reached statistical significance. GDM/HDP carried an increased risk of neonatal morbidity that was greater than that seen in either condition alone (GDM/HDP: aOR 3.13 [2.35, 4.17], P<0.001; GDM alone: aOR 2.01 [1.78, 2.27], P<0.001, HDP alone: aOR 1.38 [1.26, 1.50], P<0.001). Conclusions While GDM/HDP pregnancies have a similar median birthweight percentile to those affected by neither condition, pregnancies concurrently affected by both conditions have a higher risk of abnormal fetal growth and neonatal morbidity.