medwireNews: Better control of blood glucose around the time of conception is associated with better perinatal and maternal outcomes for women with pre-existing diabetes, research shows.
“This was especially so in women whose preconception HbA1c [glycated hemoglobin] was more than 6.4% [46 mmol/mol],” say Joel Ray (St Michael’s Hospital, Toronto, Ontario, Canada) and study co-authors.
The team’s population-based study involved 3459 pregnancies in women with prepregnancy diabetes, identified from among all live deliveries in hospitals in Ontario between 2007 and 2018. The women had blood glucose measured an average of 44.4 days before conception and at an average 13.5 weeks’ gestation.
A congenital anomaly was recorded in 14.4% of the pregnancies, and the risk for this rose by a significant 7% with each 0.5% increase in periconception HbA1c, after accounting for maternal age and periconception hemoglobin concentration.
Likewise, the risk for preterm birth rose by a significant 8% and the risk for stillbirth or neonatal death by 16% per 0.5% increase in periconception HbA1c.
Each 0.5% increase in periconception HbA1c was also associated with a significant 12% increased risk for severe maternal morbidity or death between 21 weeks’ gestation and 42 days post-delivery.
Of note, a decline in HbA1c level between the periconception and mid-pregnancy periods was associated with significant reductions in the risk for most adverse neonatal and maternal outcomes. For example, the researchers say that pregnancies with no reduction in HbA1c had a 15.6% absolute risk for a congenital anomaly, which fell to 12.0% for those with a 2.0% reduction.
However, the effect was seen only in pregnancies with a periconception HbA1c of at least 6.4% (46 mmol/mol).
Writing in JAMA Network Open, Ray and team observe that nearly half of pregnancies in Canada and the USA are unplanned.
“These results emphasize the importance of improved glycemic control prior to, and soon after, conception,” they conclude.
“As the benefit was more evident in women whose preconception HbA1c was greater than or equal to 6.4%, there may be a floor effect once HbA1c is too low to derive any additional benefit from HbA1c reduction.”
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