Why is elective induction at 38 weeks suggested over 39 weeks for a woman with gestational diabetes (GDM) on insulin therapy?

From the Guidelines

Elective induction at 38 weeks is suggested over 39 weeks for a woman with gestational diabetes on insulin therapy to reduce the risk of fetal macrosomia and balance the risks of stillbirth with fetal maturity concerns. This recommendation is based on the understanding that prolongation of gestation past 38 weeks increases the risk of fetal macrosomia without reducing cesarean rates, as noted in the study published in Diabetes Care 1. The study suggests that delivery during the 38th week is recommended unless obstetric considerations dictate otherwise.

Key Considerations

• The risk of fetal macrosomia increases with gestational age beyond 38 weeks in women with gestational diabetes mellitus (GDM) 1.
• There is no significant reduction in cesarean rates by prolonging gestation past 38 weeks in GDM pregnancies 1.
• Insulin-dependent GDM pregnancies are at a higher risk of placental insufficiency and sudden deterioration in placental function, which can lead to stillbirth, particularly after 38 weeks.
• The American College of Obstetricians and Gynecologists (ACOG) and other guidelines often recommend considering delivery by 39 weeks of gestation for women with well-controlled GDM, but the specific recommendation for insulin-dependent GDM may vary based on individual risk factors and guidelines.

Management Approach

The management approach for elective induction at 38 weeks includes careful monitoring of fetal well-being and maternal glucose levels. Insulin requirements may decrease during the induction process, and glucose monitoring is crucial to maintain target glucose levels. The decision to proceed with elective induction should be made on a case-by-case basis, considering the individual patient's risk factors and the presence of any obstetric complications.

Fetal and Maternal Outcomes

The primary goal of elective induction at 38 weeks is to balance the risks of stillbirth and fetal macrosomia with the need for fetal maturity. By inducing labor at this gestational age, the risks associated with prolonged gestation in insulin-dependent GDM pregnancies can be mitigated, potentially improving both fetal and maternal outcomes. As always, breast-feeding should be encouraged in women with GDM, as it has numerous benefits for both the mother and the baby 1.

From the Research

Elective Induction at 38 Weeks for Gestational Diabetes

The suggestion of elective induction at 38 weeks for a woman with gestational diabetes (GDM) on insulin therapy, as advised by her OB, can be understood through several key points:

• Reduction of Macrosomia Risk: Studies such as 2 and 3 indicate that induction at 38 weeks may reduce the risk of macrosomia (a condition where a baby is significantly larger than average) without increasing the rate of cesarean deliveries. This is particularly relevant for women with GDM, as their babies are at a higher risk of being larger than average.
• Balancing Risks and Benefits: The management of GDM aims to balance the control of glucose levels with the risks associated with prematurity and the potential for fetal distress or macrosomia if the pregnancy continues beyond 38 weeks. As noted in 4, excellent blood glucose control is crucial for improving perinatal outcomes.
• Previous Research Findings: A study from 5 demonstrated that strict glycemic control combined with elective early induction of labor can reduce the rate of cesarean delivery and fetal birth trauma in diabetic pregnancies. Although this study suggested induction at 38 weeks for large-for-gestational-age fetuses, the principle of early induction to prevent complications applies.
• Current Guidelines and Practices: While specific guidelines may vary, the general approach, as supported by 3, is to consider elective induction at 38 weeks for women with GDM to minimize the risks associated with continuing the pregnancy, especially if there are concerns about fetal size or well-being.

Considerations for Induction Timing

When considering the timing of elective induction, several factors are taken into account:

• Fetal Size and Well-being: The size of the baby, as mentioned, is a critical factor. Induction at 38 weeks may be recommended if the baby is estimated to be large, to prevent complications during delivery.
• Maternal Health: The health and glucose control of the mother are also crucial. Good glucose control, as emphasized in 4, is vital for preventing complications.
• Previous Studies and Recommendations: Previous studies, such as 2 and 3, suggest that induction at 38 weeks can be beneficial in reducing the risk of macrosomia without significantly increasing the risk of cesarean section or other complications.

Decision Making

The decision to proceed with elective induction at 38 weeks for a woman with GDM on insulin therapy involves careful consideration of the individual case, including:

• Risk of Macrosomia: The potential risk of the baby being significantly larger than average and the associated delivery complications.
• Glucose Control: The effectiveness of the current glucose control measures and the potential impact of continuing the pregnancy on both maternal and fetal health.
• Individual Circumstances: Other health issues or factors that might influence the decision, such as the presence of other pregnancy complications or the woman's preferences and values regarding her care.