Adverse outcomes increased but varied depending on diabetes type

Women with type 1 and type 2 diabetes consistently have an increased incidence of adverse pregnancy outcomes, including congenital anomalies, stillbirths, and neonatal deaths, as well as newborns who were large-for-gestational age (LGA), according to a recent population-based study published in The Lancet Diabetes & Endocrinology. Researchers stressed the importance of future efforts to improve glycemic control and the integration of multispecialty care of these mothers.

“As the prevalence of diabetes continues to increase, pregnancies complicated by maternal diabetes are becoming a growing concern,” wrote Helen R. Murphy, MD, of the University of East Anglia, Norwich, U.K., and fellow researchers of the National Pregnancy in Diabetes (NPID) advisory group.

“The different contributions of risk factors to obstetric complications and adverse pregnancy outcomes in women with type 1 or type 2 diabetes are unclear and have not been fully examined in the National Pregnancy in Diabetes (NPID) annual reports,” they added.

For their national population-based study, Murphy and colleagues used 5 years of data from the National Pregnancy in Diabetes audit of 172 maternity clinics throughout England, Wales, and the Isle of Man. In those locations, healthcare professionals are all required to manually enter data for all pregnant women with diabetes on a web-based form. Researchers included data from 17,375 pregnancy outcomes in 15,290 pregnant women. One-half of the women had type 1 diabetes, and the other half, type 2.

Some baseline differences were evident between the two groups. Pregnant women with type 2 diabetes had a shorter duration of diabetes compared with those with type 1 diabetes (3.0 versus 13.0 years, respectively) and were older (age at delivery: 34 versus 30 years). In addition, more women with type 2 diabetes lived in lower-socioeconomic regions (41.5% versus 24.5%), were Asian (35.6% versus 2.9%) or Black (9.6% versus 2.1%), and were overweight or obese 65.0% versus 22.8% with a BMI greater than 30).

Pregnant women with type 2 diabetes also presented 2 weeks later for antenatal care compared with those with type 1 diabetes, were more likely to be taking antihypertensive and lipid-lowering agents, and less likely to be taking preconception folic acid. In addition, however, they also had lower HbA1C levels compared with mothers with type 1 diabetes and were also more likely to achieve the NICE glycemic target of HbA1C ˂6.5% early and late in pregnancy.

Women with type 1 diabetes had significantly more preterm deliveries compared with those with type 2 diabetes (42.5% vs 23.4%, respectively; P ˂0.0001), and a higher incidence of higher LGA birthweight (52.2% vs 26.2%; P ˂0.0001).

But the incidence of neonatal deaths was higher in mothers with type 2 diabetes compared with type 1 diabetes (11.2 per 1,000 livebirths vs 7.4 per 1,000 livebirths, respectively; P=0.013).

The incidence of congenital anomalies and stillbirths were similar, however, between the two groups of mothers. Congenital anomalies occurred in 44.8 per 1,000 livebirths, terminations, and fetal losses in women with type 1 diabetes, compared with 40.5 per 1000 in women with type 2 diabetes (P=0.17). Stillbirths occurred in 10.4 per 1,000 livebirths and in 13.5 per 1,000 livebirths, respectively (P=0.072).

In analyzing the entire study population, Murphy and fellow researchers also found that the independent risk factors for perinatal death included the following:

  • Third trimester HbA1c of ≥6.5% versus ˂6.5% (OR: 3.06; 95% CI: 2.16-4.33).
  • Being in the highest deprivation quintile versus the lowest quintile (OR: 2.29; 95% CI: 1.16-4.52).
  • Having type 2 diabetes (OR: 1.65; 95% CI: 1.18-2.31).

“Our findings reinforce the crucial importance of maternal glycemia as a key modifiable risk factor and the negative effect of obesity in women with either type 1 or type 2 diabetes. Improving pregnancy outcomes is a shared challenge that will probably require new approaches for optimizing glycemic control and better integration of diabetes healthcare systems across primary care, pediatric and young adult clinics, and adult diabetes, obesity, and maternity services,” concluded Murphy and colleagues.

In light of these results, David Simmons, MD, FRACP, FRCP, of Western Sydney University, Campbelltown, NSW, Australia, in an accompanying editorial, stressed the need for improved pre- and perinatal care in all mothers with diabetes.

“Unfortunately, no improvement in pregnancy outcomes was seen among women with type 1 diabetes over the 5-year period, with a possible worsening of perinatal deaths among women with type 2 diabetes. Besides being the largest study of pregnancy outcomes in diabetes to date and providing an international benchmark for future studies, the small variation in glycemic 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,” Simmons wrote.

He also cited some of the limitations of the study: “The NPID audit has omitted some key measures (e.g., attendance at a pre-pregnancy clinic, contraception at the time of conception), and alignment with the International Association of Diabetes and Pregnancy Study Groups’ dataset for diabetes in pregnancy would have been helpful. Although more information and new studies are needed in relation to antenatal diabetes management (e.g., glycemic targets), we have evidence for how to improve pregnancy preparation in this population,” according to Simmons.

Other limitations include the inclusion of a limited number of key pregnancy outcomes, a lack of data on diabetic complications, the use of real-world clinical data, missing data, fewer HbA1C measurements in women with type 2 diabetes, and missing data on gestational weight gain.

Nevertheless, concluded Simmons, these results are key in highlighting the need for improved maternal and infant health for women with diabetes.

“The most important person to be informed and empowered is the woman with diabetes, so that they can make the best decision for themselves and access the support they need and deserve. Perhaps direct questions related to pregnancy preparedness should be the first set of additional items to be added to the NPID audit in the future,” he wrote.

  1. Rates of preterm delivery and large-for-gestational-age birthweight were higher in mothers with type 1 diabetes, while the rates of neonatal death were higher in mothers with type 2 diabetes.

  2. Independent risk factors for perinatal death (stillbirth or neonatal death) included increased third trimester HbA1c, high degree of deprivation, and type 2 diabetes.

Liz Meszaros, Contributing Writer, BreakingMED™

Murphy serves on a scientific advisory board for Medtronic.

Simmons reported no disclosures.

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