Abstract
BackgroundThe relation between prepregnancy average glucose concentration and a woman’s risk of severe maternal morbidity (SMM) is unknown. The current study evaluated whether an elevated preconception hemoglobin A1c (A1c) is associated with SMM or maternal death among women with and without known prepregnancy diabetes mellitus (DM).Methods and findingsA population-based cohort study was completed in Ontario, Canada, where there is universal healthcare. The main cohort included 31,225 women aged 16–50 years with a hospital live birth or stillbirth from 2007 to 2015, and who had an A1c measured within 90 days before conception, including 28,075 women (90%) without known prepregnancy DM. The main outcome was SMM or maternal mortality from 23 weeks’ gestation up to 42 days postpartum. Relative risks (RRs) were generated using modified Poisson regression, adjusting for the main covariates of maternal age, multifetal pregnancy, world region of origin, and tobacco/drug dependence. The mean maternal age was 31.1 years. Overall, SMM or death arose among 682 births (2.2%). The RR of SMM or death was 1.16 (95% CI 1.14–1.19; p < 0.001) per 0.5% increase in A1c and 1.16 (95% CI 1.13–1.18; p < 0.001) after adjusting for the main covariates. The adjusted relative risk (aRR) was increased among those with (1.11, 95% CI 1.07–1.14; p < 0.001) and without (1.15, 95% CI 1.02–1.29; p < 0.001) known prepregnancy diabetes, and upon further adjusting for body mass index (BMI) (1.15, 95% CI 1.11–1.20; p < 0.001), or chronic hypertension and prepregnancy serum creatinine (1.11, 95% CI 1.04–1.18; p = 0.002). The aRR of SMM or death was 1.31 (95% CI 1.06–1.62; p = 0.01) in those with a preconception A1c of 5.8%–6.4%, and 2.84 (95% CI 2.31–3.49; p < 0.001) at an A1c > 6.4%, each relative to an A1c < 5.8%. Among those without previously recognized prepregnancy diabetes and whose A1c was >6.4%, the aRR of SMM or death was 3.25 (95% CI 1.76–6.00; p < 0.001). Study limitations include that selection bias may have incorporated less healthy women tested for A1c, and BMI was unknown for many women.ConclusionsOur findings indicate that women with an elevated A1c preconception may be at higher risk of SMM or death in pregnancy or postpartum, including those without known prepregnancy DM.
Highlights
The prevalence of diabetes mellitus (DM) [1] and obesity [2] have rapidly increased worldwide
Our findings indicate that women with an elevated hemoglobin A1c (A1c) preconception may be at higher risk of severe maternal morbidity (SMM) or death in pregnancy or postpartum, including those without known prepregnancy DM
Given the known relation between both of DM and obesity and adverse pregnancy outcomes, the possibility that hyperglycemia may be associated with SMM, and the widespread availability of A1c testing, the main objective of the current study was to evaluate whether elevated preconception A1c is predictive of SMM or death, including women without previously recognized preconception DM
Summary
The prevalence of diabetes mellitus (DM) [1] and obesity [2] have rapidly increased worldwide. Prepregnancy DM and maternal obesity are each associated with a higher risk of congenital anomalies [5,6] and preterm birth [7,8]. Maternal obesity is connected with abnormal placental development [13], including a higher risk of preeclampsia [14] and severe maternal morbidity (SMM) [15]. A condition associated with obesity and hyperglycemia [16], is linked with a higher risk of preeclampsia [17] and SMM [18]. The relation between prepregnancy average glucose concentration and a woman’s risk of severe maternal morbidity (SMM) is unknown. The current study evaluated whether an elevated preconception hemoglobin A1c (A1c) is associated with SMM or maternal death among women with and without known prepregnancy diabetes mellitus (DM)
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