Gestational diabetes carries real risks for both mother and baby, but the good news is that most of those risks drop significantly with proper management. Left uncontrolled, high blood sugar during pregnancy can lead to a larger-than-normal baby, complicated delivery, dangerously low blood sugar in the newborn, and a higher chance of preeclampsia. When blood sugar is well managed through diet, exercise, and sometimes medication, the vast majority of pregnancies affected by gestational diabetes end with healthy outcomes.
Why It Happens
During pregnancy, the placenta releases a cocktail of hormones that make your body less responsive to insulin. Placental growth hormone, placental lactogen, estrogen, progesterone, prolactin, and cortisol all rise steadily as the placenta grows. These hormones interfere with insulin’s ability to move sugar out of your blood and into your cells. In most pregnancies, the pancreas compensates by producing more insulin. In gestational diabetes, the pancreas can’t keep up, and blood sugar climbs too high.
This typically develops in the second or third trimester, when placental hormone levels peak. Screening usually happens between 24 and 28 weeks, though women with higher risk factors may be tested earlier. The condition is diagnosed through a glucose tolerance test, where your blood sugar is measured after drinking a sugary solution. Diagnostic thresholds vary slightly by guidelines, but a common set of cutoffs uses a fasting level of 95 mg/dL or higher, a one-hour reading of 180 mg/dL or higher, or a two-hour reading of 153 mg/dL or higher.
Risks to the Baby During Pregnancy and Birth
The most well-known risk is macrosomia, meaning the baby grows larger than normal. When your blood sugar runs high, extra glucose crosses the placenta into the baby’s bloodstream. The baby’s pancreas responds by producing more insulin, and since insulin acts as a growth hormone in the fetus, the result is excess fat deposition and a bigger baby overall. Babies over about 8 pounds 13 ounces (4,000 grams) are more likely to get stuck during delivery, a complication called shoulder dystocia.
A large study of over 167,000 deliveries found that mothers with diabetes had roughly twice the risk of shoulder dystocia when their babies weighed under 4,000 grams, and about 1.5 times the risk when babies weighed between 4,000 and 4,500 grams. When shoulder dystocia did occur, the risk of birth trauma (such as nerve injury to the baby’s arm or collarbone fracture) was more than double in diabetic pregnancies. These complications often resolve, but they can make delivery significantly more stressful and sometimes require emergency intervention.
Large babies also increase the likelihood of needing a cesarean delivery, which carries its own recovery considerations for the mother.
What Happens to Newborns After Delivery
Babies born to mothers with gestational diabetes often experience low blood sugar in the hours and days after birth. The reason is straightforward: the baby has spent months receiving extra glucose and has been producing high levels of insulin to match. Once the umbilical cord is cut, the glucose supply stops, but the baby’s insulin levels remain elevated. That mismatch can cause blood sugar to drop too low. It can take several days for the newborn’s insulin production to adjust.
Hospital staff monitor newborn blood sugar closely after delivery, and in most cases, early and frequent feeding is enough to stabilize levels. Some babies need supplemental glucose through an IV, which may mean a stay in the neonatal intensive care unit. Babies of diabetic mothers can also have trouble with breathing, jaundice, and low calcium or magnesium levels in the first few days, though these are typically temporary and treatable.
Risks to the Mother During Pregnancy
Gestational diabetes raises the risk of preeclampsia, a dangerous condition involving high blood pressure and organ damage. The earlier gestational diabetes is diagnosed, the higher this risk appears to be. One study found that women diagnosed with gestational diabetes before 24 weeks had twice the rate of preeclampsia compared to those diagnosed later. Another found that diagnosis before 20 weeks carried an eightfold increase, even after accounting for weight and blood sugar control.
Weight gain patterns also matter. Research shows that for every additional pound per week gained after a gestational diabetes diagnosis, the probability of developing preeclampsia increased by 83%, after adjusting for other factors. This highlights why dietary management isn’t just about blood sugar control. It also helps manage the broader cardiovascular strain of pregnancy.
Long-Term Health Effects for the Child
The risks don’t entirely end at delivery. A Canadian study tracking over 3.4 million mother-infant pairs for up to 29 years found that children born to mothers with any type of diabetes during pregnancy had higher rates of cardiovascular disease, high blood pressure, and diabetes later in life. Among the diabetes subtypes, gestational diabetes carried a lower risk than pre-existing type 1 or type 2 diabetes, but the association was still present.
The study also found that pregnancy blood sugar levels were specifically linked to these cardiometabolic outcomes, suggesting that the amount of glucose exposure in the womb plays a direct role. This makes blood sugar management during pregnancy a potentially modifiable factor for the child’s long-term health, not just their birth outcomes.
Long-Term Health Effects for the Mother
After delivery, gestational diabetes resolves in the vast majority of cases. Blood sugar typically returns to normal once the placenta is delivered and its hormones clear the body. But the condition signals that your body struggled to manage insulin demand under stress, and that vulnerability persists.
A meta-analysis of 129 studies found that 17% of women with gestational diabetes eventually developed type 2 diabetes. That percentage climbed in a near-linear pattern over time: roughly a third of women developed type 2 diabetes within 15 years of their pregnancy, with the rate increasing about 12% for each additional year of follow-up. Current guidelines recommend a glucose tolerance test between 6 and 12 weeks after delivery, followed by regular screening every one to three years going forward.
This long-term risk is one of the most important things to understand about gestational diabetes. The pregnancy diagnosis is an early warning signal, and women who take it seriously by maintaining a healthy weight, staying physically active, and getting screened regularly can delay or prevent type 2 diabetes.
How Management Reduces the Danger
The reassuring part of this picture is that treatment works. Two large randomized controlled trials have demonstrated that managing gestational diabetes through lifestyle changes and, when needed, insulin significantly improves outcomes for both mother and baby. Treated pregnancies see fewer oversized babies, fewer cases of shoulder dystocia, lower rates of preeclampsia, and fewer neonatal intensive care admissions.
For most women, management starts with dietary changes and regular physical activity. The goal is to keep blood sugar within a target range after meals and during fasting. Many women achieve this with diet and exercise alone. When those measures aren’t enough, medication brings blood sugar into range. Continuous glucose monitoring has also shown promise: research found that for every 5% increase in time spent within the target blood sugar range, there were measurable reductions in large-for-gestational-age births and newborn complications.
The difference between managed and unmanaged gestational diabetes is substantial. The condition is dangerous primarily when blood sugar stays elevated throughout the pregnancy. With consistent monitoring and treatment, the risks shrink to levels that are close to, though not identical to, pregnancies without diabetes. The key is early diagnosis, steady follow-through on blood sugar management, and close communication with your care team throughout pregnancy and after delivery.