medwireNews: Data from the first 5 years of the UK’s National Pregnancy in Diabetes audit reveal differing effects of type 1 and type 2 diabetes on pregnancy outcomes, with no sign of improvements over time.
The findings are published in The Lancet Diabetes & Endocrinology, along with a commentary from David Simmons (Western Sydney University, New South Wales, Australia).
He writes: “Besides being the largest study of pregnancy outcomes in diabetes to date and providing an international benchmark for future studies, the small variation in glycaemic and neonatal outcomes despite the provision of the annual benchmarking data, and the absence of substantial between-clinic variation in outcomes, support the need for systemic change.”
Helen Murphy (University of East Anglia, Norwich, UK) and colleagues assessed 17,375 pregnancy outcomes in 8690 women with type 1 diabetes and 8685 with type 2 diabetes from 2014 through 2018. Women with type 1 diabetes gave birth at a median of 30 years of age and 13 years of diabetes; for those with type 2 diabetes it was a corresponding 34 years old and 3 years’ duration.
The researchers found that women with type 1 diabetes were significantly more likely to give birth preterm, at 42.5% versus 23.4% in women with type 2 diabetes, and to have babies who were large for gestational age, at 52.2% versus 26.2%. Moreover, the rates of these outcomes in women with type 1 diabetes increased during the study period.
Women with type 2 diabetes, by contrast, were significantly more likely to have a small for gestational age baby, at 14.1% versus 5.4%. They were also significantly more likely to experience neonatal death, at 1.1% versus 0.7%. Rates of stillbirth were similar in the two groups, but appeared to increase in women with type 2 diabetes during the last 2 years of the study whereas they remained stable in those with type 1 diabetes.
For all women combined, having third trimester glycated hemoglobin (HbA1c) levels of 6.5% (48 mmol/mol) or higher was independently associated with a 3.06-fold increased risk for perinatal death, as was being in the highest versus the lowest deprivation quintile, at a 2.29-fold increased risk. Having type 2 rather than type 1 diabetes was associated with a 1.65-fold increase in risk.
Average third trimester HbA1c levels were higher in women with type 1 rather than type 2 diabetes, at 6.7% versus 6.0% (50 vs 42 mmol/mol), and these were higher in both groups in women with a higher BMI. Women with type 2 diabetes were more likely to be in the most deprived quintile, at 41.5% versus 24.5% of those with type 1 diabetes, but the researchers note that even the rate for women with type 1 diabetes was higher than in the general population.
The two groups of women had similar rates of congenital anomalies, the risk for which was significantly increased in those with HbA1c levels of 6.5% or higher in the first trimester, and those who did not take folic acid prior to conception.
The specific maternity clinic attended, out of the 172 in the study, was not an independent predictor of pregnancy outcomes, with the team finding “minimal variation between clinics, with most being within the expected distribution.”
In his commentary, Simmons says: “Pre-pregnancy clinics, direct information to women, education of health-care professionals, and easy access to effective contraception are already available.”
He concludes: “These measures can reduce harm, are effective, and are probably cost saving, and they need to be systematically introduced, just as continuous glucose monitoring is now increasingly accessible.”
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