Maternal and neonatal outcomes according to the timing of diagnosis of hyperglycaemia in pregnancy: a nationwide cross-sectional study of 695,912 deliveries in France in 2018

Abstract

Aims/hypothesis: We aimed to assess maternal-fetal outcomes according to various subtypes of hyperglycaemia in pregnancy.

Methods: We used data from the French National Health Data System (Système National des Données de Santé), which links individual data from the hospital discharge database and the French National Health Insurance information system. We included all deliveries after 22 gestational weeks (GW) in women without pre-existing diabetes recorded in 2018. Women with hyperglycaemia were classified as having overt diabetes in pregnancy or gestational diabetes mellitus (GDM), then categorised into three subgroups according to their gestational age at the time of GDM diagnosis: before 22 GW (GDM_<22); between 22 and 30 GW (GDM_22-30); and after 30 GW (GDM_>30). Adjusted prevalence ratios (95% CI) for the outcomes were estimated after adjusting for maternal age, gestational age and socioeconomic status. Due to the multiple tests, we considered an association to be statistically significant according to the Holm-Bonferroni procedure. To take into account the potential immortal time bias, we performed analyses on deliveries at ≥31 GW and deliveries at ≥37 GW.

Results: The study population of 695,912 women who gave birth in 2018 included 84,705 women (12.2%) with hyperglycaemia in pregnancy: overt diabetes in pregnancy, 0.4%; GDM_<22, 36.8%; GDM_22-30, 52.4%; and GDM_>30, 10.4%. The following outcomes were statistically significant after Holm-Bonferroni adjustment for deliveries at ≥31 GW using GDM_22-30 as the reference. Caesarean sections (1.54 [1.39, 1.72]), large-for-gestational-age (LGA) infants (2.00 [1.72, 2.32]), Erb's palsy or clavicle fracture (6.38 [2.42, 16.8]), preterm birth (1.84 [1.41, 2.40]) and neonatal hypoglycaemia (1.98 [1.39, 2.83]) were more frequent in women with overt diabetes. Similarly, LGA infants (1.10 [1.06, 1.14]) and Erb's palsy or clavicle fracture (1.55 [1.22, 1.99]) were more frequent in GDM_<22. LGA infants (1.44 [1.37, 1.52]) were more frequent in GDM_>30. Finally, women without hyperglycaemia in pregnancy were less likely to have preeclampsia or eclampsia (0.74 [0.69, 0.79]), Caesarean section (0.80 [0.79, 0.82]), pregnancy and postpartum haemorrhage (0.93 [0.89, 0.96]), LGA neonate (0.67 [0.65, 0.69]), premature neonate (0.80 [0.77, 0.83]) and neonate with neonatal hypoglycaemia (0.73 [0.66, 0.82]). Overall, the results were similar for deliveries at ≥37 GW. Although the estimation of the adjusted prevalence ratio of perinatal death was five times higher (5.06 [1.87, 13.7]) for women with overt diabetes, this result was non-significant after Holm-Bonferroni adjustment.

Conclusions/interpretation: Compared with GDM_22-30, overt diabetes, GDM_<22 and, to a lesser extent, GDM_>30 were associated with poorer maternal-fetal outcomes.

Keywords: Caesarean section; Diabetes; Gestational diabetes mellitus; Macrosomia; Overt diabetes in pregnancy; Perinatal death; Preeclampsia; Pregnancy; Prematurity.

Fig. 1

Crude rates of maternal and neonatal outcomes for the study according to maternal glycaemic status (n=695,912) (France, 2018). All overall p values were <0.0001, except for malformations, where the p value was 0.008

Fig. 2

aPR of maternal outcomes among deliveries occurring at ≥31 GW (n=688,627 deliveries) or ≥37 GW (n=654,902) according to maternal glycaemic status (France, 2018). *p values statistically significant after Holm–Bonferroni adjustment. For each perinatal outcome, two forest plots are presented: one for deliveries at ≥31 GW (left) and one for deliveries at ≥37 GW (right). Ref, reference

Fig. 3

aPR of neonatal outcomes (LGA, Erb’s palsy/clavicle fracture, prematurity, neonatal hypoglycaemia) among deliveries occurring at ≥31 GW (n=688,627 deliveries) or ≥37 GW (n=654,902) according to maternal glycaemic status (France, 2018). *p values statistically significant after Holm–Bonferroni adjustment. For each perinatal outcome (except for prematurity), two forest plots are presented: one for deliveries at ≥31 GW (left) and one for deliveries at ≥37 GW (right). Ref, reference

Fig. 4

aPR of neonatal outcomes (fetal distress, NICU, congenital malformation, perinatal death) among deliveries occurring at ≥31 GW (n=688,627 deliveries) or ≥37 GW (n=654,902) according to maternal glycaemic status (France, 2018). *p values statistically significant after Holm–Bonferroni adjustment. For each perinatal outcome, two forest plots are presented: one for deliveries at ≥31 GW (left) and one for deliveries at ≥37 GW (right). Ref, reference