Type 1, Type 2 Diabetes Associated with Higher Pregnancy Complication Risk

Robert Lindsay, MBChB, PhD

A rise in the risk of pregnancy complications, such as stillbirths, the need for emergency Caesarean sections, and even infant mortality, have been associated with both type 1 (T1D) and type 2 diabetes (T2D).

New research from the University of Glasgow revealed that stillbirth and perinatal mortality is around 3 to 5 times more likely for women with diabetes compared to the wider population, and that the number of pregnancies complicated by diabetes increased by 44% for T1D (1 in 210 births) and 90% with T2D (1 in 504 births) from 1998 to 2013.

The investigators were led by Sharon Mackin, MD, a clinical research fellow in the Department of Cardiovascular and Medical Sciences, and Robert Lindsay, MBChB, PhD, an associate professor in the Institute of Cardiovascular and Medical Sciences.

“Women with diabetes are receiving increased intervention in pregnancy (earlier delivery, increased Caesarean section rates), but despite this, higher birth weights are being recorded,” they wrote. “Improvements in rates of stillbirth seen in the general population are not being reflected in changes in stillbirth or perinatal mortality in our population with diabetes.”

Data was collected from the Scottish Morbidity Record 02 (SMR02), covering all infant deliveries in Scotland between April 1, 1998, and March 31, 2013. Overall, it included 813,921 deliveries. Diabetes status of mothers was determined via the Scottish Care Information—Diabetes Collaboration (SCI-diabetes), which reportedly covers 99.5% of patients with diabetes in Scotland, since 2004.

"The importance of our paper is first that it is from a comprehensive national dataset so is complete for a geographical patient group," Lindsay told MD Magazine. "Other surveys from a particular clinic or insurance system necessarily include a degree of potential patient selection. Second, that we have longitudinal data. A number of new technologies are becoming available such as novel glucose monitoring systems and pump technologies. From a personal, clinical perspective, the importance of this work to me is in defining where we are with current technologies and identifying an unmet need for these novel developments."

In total, 4681 (0.6%) births were to mothers with pregestational T1D or T2D. Of that, 3229 (69%) had T1D (mean time with the condition, 13.3 years) and 1452 (31%) had T2D (mean time with the condition, 3.3 years).

Compared to women without diabetes, deliveries occurred an average of 2.6 weeks earlier for T1D (36.7 ±2.3 weeks) and 2.0 weeks earlier for T2D (37.3 ±2.4 weeks). In the study period, time to delivery decreased significantly, from 36.7 to 36.4 weeks for T1D (P = .03) and from 38.0 to 37.2 weeks for T2D (P <.001).

Rates of preterm delivery were increased for women with diabetes as well—35.3% with T1D and 21.8% with T2D, compared to 6.1% without diabetes (P <.0001). Birth weight was also increased for women with diabetes, with T1D birth weights increasing over the study period.

In the 15-year span of the study, there were 104 perinatal deaths with mothers with diabetes, with 65 occurring with mothers with T1D and 39 with mothers with T2D, equaling a mortality rate 4.2 and 3.1 times higher, respectively than the general population. The mortality rate was 20.1 (95% CI, 14.7-24.3) for T1D and 26.9 (95% CI, 16.7-32.9) for T2D per 1000 births (P <.001).

"The data for type 2 diabetes are important, as while again, outcomes for these women have been described previously in reports are far fewer," Lindsay said. "While the numbers are slightly different, I think the message would be that both types of diabetes essentially carry a similar increase in risk. We do not report on gestational diabetes in this paper, but I would expect that risks here will be considerably lower than either T1D or T2D."

Stillbirths were found to be 4.0 and 5.1 times higher than in the non-diabetic population (P <.001). The authors acknowledged small drops in the rates of stillbirth and perinatal mortality for the non-diabetic population but noted that no significant fall was reported in the diabetic population.

Elective Caesarean sections were reportedly much higher for mothers with diabetes (29.4% T1D, 30.5% T2D) than those without (9.6%), with echoed results for emergency Caesarean sections (38.3% T1D, 29.1% T2D, 14.6% non-diabetic). Other than for mothers with T1D, whose rates of emergency Caesarean sections remained stable, rates of their occurrence increased over the study period.

The study, “Diabetes and pregnancy: national trends over a 15 year period,” was published in Diabetologia.

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