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Maternal blood glucose, BMI linked to stillbirth risk in diabetes before pregnancy
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Women with type 1 or type 2 diabetes can reduce the elevated risk for stillbirth by working to achieve normoglycemia and a healthy BMI before and during pregnancy, according to findings published in Diabetologia.
“Prevention of stillbirth underpins part of the clinical rationale for obstetric intervention in diabetes, particularly around timing of delivery,” Robert S. Lindsay, MBChB, PhD, FRCP(Glasg), a reader in diabetes and endocrinology and honorary consultant at the British Heart Foundation Glasgow Cardiovascular Research Centre of the University of Glasgow in Scotland, and colleagues wrote in the study background. “While we lack predictive models, presence of risk factors may guide obstetricians to earlier delivery, which is appropriate in many cases but associated with neonatal morbidity.”
In a retrospective study, Lindsay and colleagues analyzed data from 5,392 singleton infants — born to 3,778 women with type 1 diabetes and 1,614 women with type 2 diabetes — delivered at or beyond 24 weeks’ gestation between April 1998 and June 2016, using data from the Scottish Morbidity Record 2 and the Scottish Care Information-Diabetes. Researchers compared maternal and fetal characteristics, including HbA1c data, infant size and delivery timing, between stillborn and liveborn groups.
Within the cohort, stillbirth rates were 16.1 per 1,000 births (95% CI, 12.4-20.8) for women with type 1 diabetes (n = 61) and 22.9 per 1,000 births (95% CI, 16.4-31.8) for women with type 2 diabetes (n = 37).
Among women with type 1 diabetes, 52% of infants (live and stillborn) were large for gestational age, with higher birth weight related to higher maternal HbA1c. Also among these women, researchers found that a higher HbA1c before pregnancy (OR = 1.03; 95% CI, 1.01-1.04) and in later pregnancy (OR = 1.06; 95% CI, 1.04-1.08) were associated with stillbirth risk. Among women with type 2 diabetes, higher maternal BMI (OR = 1.07; 95% CI, 1.01-1.14) and pre-pregnancy HbA1c (OR = 1.02; 95% CI, 1-1.04) were associated with stillbirth risk.
The researchers found that stillbirth risk was highest among infants small for gestational age, with a sixfold higher risk for infants born to women with type 1 diabetes (n = 5 stillbirths; 67 livebirths) and a threefold higher risk for infants born to women with type 2 diabetes (n = 4 stillbirths; 78 livebirths) compared with infants in the 10th to 90th centile for weight (n = 20 stillbirths; 1,685 livebirths). Risk for stillbirth was twice as high among infants large for gestational age born to women with type 2 diabetes (n = 15 stillbirths; 402 livebirths) compared with infants in the 10th to 90th centile for weight.
The researchers also observed that a high proportion of stillborn infants were male among mothers with type 2 diabetes (81.1% of stillbirths vs. 50.5% livebirths; P = .0002). One-third of stillbirths occurred at term, with highest rates observed in the 38th week of pregnancy among mothers with type 1 diabetes (7 per 1,000 ongoing pregnancies; 95% CI, 3.7-12.9) and in the 39th week of pregnancy among mothers with type 2 diabetes (9.3 per 1,000 ongoing pregnancies; 95% CI, 2.4-29.2).
“It would seem then that earlier delivery would be a sensible approach,” Lindsay and colleagues said in a press release. “However, because of potential issues with early delivery, including respiratory distress syndrome as a result of inadequate lung development, we suggest that the increased risk of neonatal morbidity needs to be more formally explored before recommendations for optimal timing of delivery are made, particularly where mothers are managing to obtain almost normal blood glucose levels.”
The researchers noted that the achievement of “near-normal” blood glucose remains key to reducing risk, and recommended methods of support for women to improve blood glucose in pregnancy, along with programs to optimize weight before pregnancy. – by Regina Schaffer
Disclosures: Lindsay reports he has served on advisory boards for Eli Lilly, Novo Nordisk and Servier. Please see the study for all other authors’ relevant financial disclosures.
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