Meeting paper
SMFM paper
What is the optimal gestational age for women with gestational diabetes type A1 to deliver?

Presented in poster format at the 34th annual meeting of the Society for Maternal-Fetal Medicine, New Orleans, LA, Feb. 3-8, 2014.
https://doi.org/10.1016/j.ajog.2014.06.015Get rights and content

Objective

Type A1 gestational diabetes mellitus (A1GDM), also known as diet-controlled gestational diabetes, is associated with an increase in adverse perinatal outcomes such as macrosomia and Erb palsy. However, it remains unclear when to deliver these women because optimal timing of delivery requires balancing neonatal morbidities from early term delivery against the risk of intrauterine fetal demise (IUFD). We sought to determine the optimal gestational age (GA) for women with A1GDM to deliver.

Study Design

A decision-analytic model was built to compare the outcomes of delivery at 37-41 weeks in a theoretical cohort of 100,000 women with A1GDM. Strategies involving expectant management until a later GA accounted for probabilities of spontaneous delivery, indicated delivery, and IUFD during each week. GA-associated risks of neonatal complications included cerebral palsy, infant death, and Erb palsy. Probabilities were derived from the literature, and total quality-adjusted life years were calculated. Sensitivity analyses were used to investigate the robustness of the baseline assumptions.

Results

Our model showed that induction at 38 weeks maximized quality-adjusted life years. Within our cohort, delivery at 38 weeks would prevent 48 stillbirths but lead to 12 more infant deaths compared to 39 weeks. Sensitivity analysis revealed that 38 weeks remains the optimal timing of delivery until IUFD rates fall <0.3-fold of our baseline assumption, at which point expectant management until 39 weeks is optimal.

Conclusion

By weighing the risks of IUFD against infant deaths and neonatal morbidities from early term delivery, we determined that the ideal GA for women with A1GDM to deliver is 38 weeks.

Section snippets

Materials and Methods

A decision-analytic model was created using TreeAge software (TreeAge Pro 2013; TreeAge Software, Inc., Williamstown, MA) to compare the outcomes of planning to deliver at 37-41 weeks in a theoretical cohort of 100,000 women with A1GDM (Figure 1). Strategies involving expectant management until a later GA accounted for probabilities of spontaneous delivery, indicated delivery, and IUFD during each successive week. GA-associated risks of neonatal complications included cerebral palsy, infant

Results

Both maternal and neonatal outcomes were predicted in our theoretical model of 100,000 women with A1GDM. We found that planned delivery of these women at 38 weeks’ gestation was the optimal timing of delivery, which maximized QALYs. In our theoretical cohort, delivering at 38 weeks resulted in 48 fewer stillbirths but 12 more infant deaths compared to delivery at 39 weeks (Table 2). Additionally, delivering women at 38 weeks compared to 39 weeks reduced the maternal death rate from 16.2 per

Comment

Our model, based on a theoretical cohort of 100,000 women with A1GDM, demonstrated that the optimal time to plan to deliver these women was 38 weeks to minimize adverse perinatal maternal and neonatal outcomes. Delivering at 38 weeks’ gestation remained the optimal strategy until infant death rates increased to a threshold of 3.73 times above our baseline assumptions, cerebral palsy rates increased to 3.79 times above our baseline assumptions, or IUFD rates increased to 1.90 times above our

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This publication was supported by the Oregon Clinical and Translational Research Institute (OCTRI), grant number (TL1TR000129) from the National Center for Advancing Translational Sciences (NCATS) at the National Institutes of Health (NIH) (B.N.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

The authors report no conflict of interest.

Cite this article as: Niu B, Lee VR, Cheng YW, et al. What is the optimal gestational age for women with gestational diabetes type A1 to deliver? Am J Obstet Gynecol 2014;211:418.e1-6.

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