Preexisting Diabetes, Maternal Glycated Hemoglobin, and the Risks for Fetal and Infant Death: A Population-Based Study

Diabetes, a common preexisting maternal condition complicating pregnancy, affects 0.5% to 2% of parturients. Optimizing glycemic control can improve birth outcomes in these women. Data from several population-based registers in the North of England were used to investigate the association between preexisting diabetes and risks of fetal and infant death in normally formed offspring and to quantify the contribution of glycemic control. Data were obtained on all singleton pregnancies in women with preexisting diabetes who delivered at 20 weeks’ gestation or later between 1996 and 2008. Prevalence rates were estimated per 1000 births and late miscarriages for fetal outcomes and per 1000 live births for infant outcomes. Relative risks (RRs), odds ratios, and 95% confidence intervals (CIs) were calculated for all variables influencing fetal or infant death and analyzed as related to fetal death, late stillbirth, infant death, fetal and infant death combined, and late stillbirth and infant death combined. Periconception glycated hemoglobin (HbA1c) concentration was considered a surrogate of preconception HbA1c concentration. Of 397,392 singleton live births, stillbirths, and late miscarriages uncomplicated by major congenital anomalies, 1548 women had preexisting diabetes, a prevalence of 3.9 (95% CI, 3.7–4.1) per 1000 deliveries. Rates for type 1 and type 2 diabetes were 78% and 22%, respectively. The median periconception and third-trimester HbA1c concentrations were 62 mM/M (interquartile range [IQR], 51–76; 7.8%; IQR, 6.8–9.1) and 50 mM/M (IQR, 43–58; 6.7%; IQR, 6.1–7.5), respectively. Five late miscarriages, 38 antepartum stillbirths, and 3 intrapartum stillbirths and 6 neonatal deaths and 4 postneonatal deaths occurred in the women with preexisting diabetes. The prevalence of fetal death in the women with preexisting diabetes was 29.7 (95% CI, 21.8–39.4), more than 4 times greater than in those without diabetes (RR, 4.56; 95% CI, 3.42–6.07). The prevalence of fetal death did not differ significantly for the women with type 1 (2.8%) and those with type 2 diabetes (3.5%; P = 0.51). The estimated RRs for a preterm fetal loss, term stillbirth, and late miscarriage in the women with preexisting diabetes versus those without were 4.95 (95% CI, 3.59–6.82), 5.05 (95% CI, 2.62–9.71), and 1.61 (95% CI, 0.67–3.86), respectively. The prevalence of infant death in the women with preexisting diabetes was 6.7 per 1000 compared with 1.86 per 1000 in those without (P = 0.046). The prevalence of infant death did not differ significantly between the women with type 1 (7.7 per 1000) and those with type 2 disease (3.0 per 1000; P = 0.70). Increasing periconception HbA1c concentration of greater than 49 mM/M (6.6%), prepregnancy retinopathy, and lack of prepregnancy folic acid intake were all independently associated with increased odds of fetal and infant death, but the effects did not differ between the women with type 1 and 2 diabetes. Increasing third-trimester HbA1c concentration of greater than 43 mM/M and lack of prepregnancy folic acid intake were the only variables significantly associated with the odds of a late stillbirth or infant death. Increasing periconception HbA1c concentration of greater than 49mM/Mwas the only variable significantly associated with fetal death or infant death. 315 Medical Complications of Pregnancy Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. The prevalence of fetal death was more than 4 times greater in the women with preexisting diabetes, and the prevalence of infant death was nearly doubled. The RR of fetal and infant death associated with preexisting diabetes did not decrease over time, and the RR of stillbirth varied by gestational age. To reduce the RR of stillbirth and infant death in women with preexisting diabetes, barriers to obtaining preconception care and adequate preparation for pregnancy must be further investigated.