Adverse Outcomes Risk Increases for Pregnant Women with Diabetes

Helen R. Murphy, MD

Diabetes for pregnant women is often linked to preterm delivery, birthweight extremes, and increased rates of congenital anomaly, stillbirth, and neonatal death.

A team, led by Helen R. Murphy, MD, Bob Champion Research and Education Building, University of East Anglia, identified and compared modifiable risk factors associated with adverse pregnancy outcomes in women with type 2 diabetes and those with type 2 diabetes, while identifying effective maternity clinics.

A Nationwide Sample

In the national population-based cohort, the researchers used data for pregnancies among with either diabetes type from the first 5 years of the National Pregnancy in Diabetes audit across 172 maternity clinics in England, Wales, and the Isle of Man.

Specifically, they obtained data for obstetric complications (preterm delivery [less than 37 weeks’ gestation] large for gestational age [LGA] birthweight [>90th percentile]), and adverse pregnancy outcomes (congenital anomaly, stillbirth, neonatal death) for pregnancies completed between 2014-2018. 

The researchers also assessed the associations between modifiable (HbA _1c, BMI, pre-pregnancy care, maternity clinic) and non-modifiable risk factors (age, ethnicity, deprivation, duration of type 1 diabetes) with pregnancy outcomes in women with type 1 diabetes compared with those with type 2 diabetes.

Modeling

In addition, the researchers used a regression model to calculate the associations between maternal factors and perinatal deaths, including diabetes type and duration, maternal age, body mass index (BMI), deprivation quintile, first trimester HbA _1c, preconception folic acid, potentially harmful medications, and third trimester HbA _1c.

Overall, the researchers used the data from 17,375 pregnancy outcomes from 15,290 pregnant women. In this group, 8690 (50%) of the pregnancies were in women with type 1 diabetes. The median age at delivery was 30 years old and the median duration of diabetes was 13 years.

The other half of the patient population (n = 8695; 50%) suffered from type 2 diabetes, with a median age at delivery of 34 years old and a median duration of diabetes of 3 years.

Adverse Events

The rates of preterm delivery (n = 3325; 42.5% among women with type 1 diabetes; n = 1825; 23.4% among women with type 2 diabetes; P <0.0001), and LGA birthweight (n = 4095; 52.2% among women with type 1 diabetes; n = 2065; 26.2% among women with type 2 diabetes; P <0.0001) were higher in type 1 diabetes.

In addition, the prevalence of congenital anomaly (among women with type 1 diabetes, 44.8 per 1000 livebirths, terminations, and fetal losses; among women with type 2 diabetes, 40.5 per 1000 livebirths, terminations, and fetal losses; P = 0.17) and stillbirth (type 1 diabetes, 10.4 per 1000 livebirths and stillbirths; type 2 diabetes, 13.5 per 1000 livebirths and stillbirths; P = 0.072) did not significantly differ between diabetes types.

However, rates of neonatal deaths were still higher in patients with type 2 diabetes than it was for the mothers with type 1 diabetes type 1 diabetes, 7.4 per 1000 livebirths; type 2 diabetes, 11.2 per 1000 livebirths; P = 0.013).

Further analysis of the entire study population show independent risk factors for perinatal death were third trimester HbA _1c of 6.5% (48 mmol/mol) or higher (OR, 3.06; 95% CI, 2.16–4.33 vs HbA _1c <6.5%), being in the highest deprivation quintile (OR, 2.29; 95% CI, 1.16–4.52] vs the lowest quintile), and having type 2 diabetes (OR, 1.65; 95% CI, 1.18–2.31 vs type 1 diabetes).

Finally, variations in HbA _1c and LGA birthweight were linked to maternal characteristics, including age, diabetes duration, deprivation, BMI without substantial differences between maternity clinics.

“Our data highlight persistent adverse pregnancy outcomes in women with type 1 or type 2 diabetes,” the authors wrote. “Maternal glycaemia and BMI are the key modifiable risk factors. No maternity clinics were had appreciably better outcomes than any others, suggesting that health-care system changes are needed across all clinics.”

The study, "Characteristics and outcomes of pregnant women with type 1 or type 2 diabetes: a 5-year national population-based cohort study," was published online in The Lancet Diabetes & Endocrinology.