What are the growth patterns of large for gestational age (LGA) babies born to mothers with gestational diabetes mellitus (GDM)?

From the Guidelines

Babies born to mothers with gestational diabetes mellitus (GDM) often exhibit distinctive growth patterns, typically resulting in large for gestational age (LGA) infants, and careful maternal glucose control during pregnancy can significantly reduce the likelihood and severity of LGA outcomes. These babies tend to develop asymmetric macrosomia, characterized by increased fat deposition particularly in the shoulders, trunk, and abdomen, while head circumference remains relatively proportional. This growth pattern occurs because maternal hyperglycemia leads to fetal hyperinsulinemia, as glucose readily crosses the placenta while maternal insulin cannot. The fetal pancreas responds by producing excess insulin, which acts as a growth hormone and promotes fat storage. LGA babies from GDM mothers typically show accelerated growth beginning in the second trimester, with the most dramatic increases occurring in the third trimester. These infants often have birth weights above the 90th percentile, with disproportionate trunk and shoulder circumference compared to head size. After birth, these babies may experience rapid drops in blood glucose due to the sudden removal of maternal glucose supply while their insulin production remains high. Long-term, these children face increased risks of childhood obesity and metabolic disorders, as the intrauterine metabolic programming may predispose them to insulin resistance later in life. According to the most recent study 1, maternal lipid levels in early to mid-pregnancy, such as higher triglycerides, total cholesterol, and LDL-C, were positively associated with birthweight as well as LGA and fetal macrosomia.

Some key points to consider in managing GDM include:

• Lifestyle behavior change is an essential component of management of gestational diabetes mellitus and may suffice as treatment for many individuals 1
• Insulin is the preferred medication for treating hyperglycemia in gestational diabetes mellitus 1
• Maternal glucose control during pregnancy through diet, exercise, and when necessary, medications like insulin or metformin, can significantly reduce the likelihood and severity of LGA outcomes
• Telehealth visits for pregnant people with gestational diabetes mellitus improve outcomes compared with standard in-person care 1
• The risk of GDM may be reduced by diet, exercise, and lifestyle counseling, particularly when interventions are started during the first or early in the second trimester 1

Overall, careful management of GDM is crucial to reduce the risk of LGA outcomes and improve the health of both the mother and the child. The most effective approach to managing GDM is to maintain tight glucose control through a combination of lifestyle modifications and medication, as needed, and to monitor fetal growth and development closely.

From the Research

Growth Patterns of LGA Babies Born to Gestational Diabetic Mothers

• The growth patterns of LGA babies born to gestational diabetic mothers can be influenced by various factors, including maternal glycemia and glucose-lowering measures 2, 3.
• A study found that both low and high fasting glucose values at 22-30 weeks of gestation are associated with increased risk of an LGA newborn 2.
• Another study found that patients treated with insulin had a higher incidence of neonatal intensive care unit (NICU) occupancy and large for gestational age (LGA) newborns than those treated with metformin 3.
• Metformin has been shown to be a potentially superior choice for GDM treatment, as it is associated with minimal incidences of multiple adverse pregnancy outcome indicators and does not lead to high values of certain adverse outcome indices 3, 4.

Maternal and Infant Outcomes

• A network meta-analysis found that metformin is associated with lower rates of neonatal hypoglycemia, macrosomia, LGA, and NICU occupancy compared to other glucose-lowering measures 3.
• A randomized prospective trial found that metformin treatment was associated with better postprandial glycemic control, a lower risk of hypoglycemic episodes, less maternal weight gain, and a low rate of failure as an isolated treatment 4.
• The incidence of T2DM was found to be higher in women with GDM who delivered an LGA infant, suggesting that these women are at an increased risk for subsequent development of T2DM 5.

Risk Factors for LGA Newborns

• Maternal glycemia, particularly high fasting glucose values, has been identified as a risk factor for LGA newborns 2.
• The use of insulin as a glucose-lowering measure has also been associated with an increased risk of LGA newborns 3.
• Women with GDM who deliver an LGA infant are at an increased risk for subsequent development of T2DM, highlighting the importance of close monitoring and intervention to delay or prevent T2DM development 5.