Gestational diabetes mellitus (GDM) is a condition where a person develops high blood sugar levels during pregnancy. Hormones from the placenta create insulin resistance, preventing the body from using insulin effectively, which causes glucose to build up in the bloodstream. For many diagnosed with GDM, the immediate concern is whether this diagnosis automatically means labor will be induced. The necessity of an induced delivery is a decision based on how well the condition is controlled and the continuous health of the baby.
Why Gestational Diabetes Affects Delivery
The primary concern with uncontrolled GDM is the excessive transfer of glucose across the placenta to the developing baby. The baby’s pancreas responds to this extra sugar by producing more insulin, which acts as a growth hormone. This causes the baby to store surplus glucose as fat, leading to fetal macrosomia. Macrosomia is defined as the baby growing significantly larger than average, often weighing more than 8 pounds, 13 ounces (4,000 grams).
A large baby increases the risk of birth complications, particularly shoulder dystocia, where the baby’s shoulder gets stuck behind the pelvic bone. Shoulder dystocia can cause nerve damage to the baby’s arm or require emergency maneuvers, which is a major factor in considering an earlier induction. Poorly controlled GDM can also cause the placenta to age more rapidly, reducing its efficiency in delivering oxygen and nutrients. This placental deterioration contributes to a higher risk of stillbirth, especially as the pregnancy progresses beyond the due date.
Standard Guidelines for Delivery Timing
The decision to induce labor is closely tied to the category of GDM control, which is divided into two main groups. GDM managed successfully through diet and exercise alone is classified as diet-controlled GDM. For these pregnancies, the risk of stillbirth is considered comparable to that of an unaffected pregnancy, meaning early induction is often not necessary.
Medical organizations recommend that diet-controlled GDM can be managed expectantly up to 40 weeks and six days of gestation, provided fetal monitoring remains reassuring. Induction before 39 weeks is avoided unless there are other complications, such as a large estimated fetal weight or high blood pressure. The goal is to allow the pregnancy to continue as close to its natural term as possible while mitigating the risks associated with GDM.
The second category is GDM requiring medication, including those needing insulin or oral agents to maintain target blood sugar levels. Because this group indicates more challenging glycemic control, it is associated with a higher risk of complications, including stillbirth. Therefore, an earlier induction is advised to minimize the risk of adverse outcomes.
For medication-controlled GDM, the current recommendation is to plan for delivery between 39 weeks and 0 days and 39 weeks and 6 days of gestation. Delivery may be considered as early as 38 weeks if there are concerns about the baby’s growth or difficult blood sugar control. This earlier timing aims to balance the risk of late-term complications against the risks associated with delivering before 39 weeks.
Fetal Surveillance and Shared Decision Making
To determine the safest delivery timing, the healthcare team relies on regular fetal surveillance in the final weeks of pregnancy. This monitoring assesses the baby’s well-being and identifies any signs of distress or placental dysfunction. Common tools include the Non-Stress Test (NST), which records the baby’s heart rate in response to movement. Another tool is the Biophysical Profile (BPP), an ultrasound that assesses markers of fetal health, including breathing, movement, muscle tone, and amniotic fluid volume.
For GDM managed with medication, surveillance typically begins around 32 weeks of gestation, and testing is performed once or twice weekly. If the GDM is diet-controlled, surveillance may start later or not at all, depending on specific risk factors and local practice guidelines. The results of these tests, combined with periodic growth ultrasound scans, provide a dynamic picture of the baby’s condition that informs the delivery plan.
The final decision about induction timing is a process of shared decision making between the patient and their clinician, not solely based on test results. This involves a thorough discussion of the potential benefits of induction, such as reducing the risk of stillbirth and macrosomia-related injury. It also covers the potential drawbacks of an earlier delivery. The patient’s informed choice and understanding of the risks associated with both induction and expectant management play an important role in establishing the delivery date.