Metformin in Pregnancy: What Happens to Children Years Later?

Metformin is widely used to manage type 2 diabetes and is sometimes prescribed during pregnancy. However, questions remain about its long-term effects on children exposed before birth. A new population-based study offers important insights into how metformin use during pregnancy may affect child development, examining physical, emotional, social, and learning abilities years after prenatal exposure. The findings are reassuring, but they also highlight why careful clinical interpretation remains essential.

Table of Contents

1. What We Know About Metformin Use During Pregnancy
2. What the Study Found About Children's Development After Metformin Exposure
3. Understanding the Study's Limitations
4. Implications for Diabetes Care During Pregnancy
5. Conclusion
6. Frequently Asked Questions

What We Know About Metformin Use During Pregnancy

Metformin, commonly sold under the brand name Glucophage, lowers blood glucose mainly by reducing glucose production in the liver and improving insulin sensitivity. Clinicians prescribe it for type 2 diabetes and sometimes for gestational diabetes mellitus (GDM).

Unlike insulin, metformin crosses the placenta and reaches the developing fetus. Consequently, researchers have questioned whether prenatal exposure could influence childhood growth, metabolism, or brain development.

Previous studies have examined birth weight, body composition, and childhood obesity following maternal metformin use. However, the findings have not always been consistent. Some follow-up studies identified differences in childhood weight and body measurements, while others found no meaningful changes.

Moreover, evidence about learning, communication, and social development has remained limited. These outcomes matter because children may not show developmental differences until they begin school.

Earlier research on metformin use during pregnancy explored its clinical benefits and potential safety concerns.

The latest research extends that discussion by examining childhood developmental outcomes rather than focusing only on pregnancy complications or newborn health.

What the Study Found About Children's Development After Metformin Exposure

A population-linked cohort study published September 30, 2026, in JAMA Network Open examined the association between prenatal metformin exposure and developmental vulnerability at school entry.

Researchers analyzed pregnancy and birth records from Victoria, Australia, covering 2009 through 2020. They linked those records to childhood assessments conducted when children were approximately 4 to 6 years old.

The final study included 177,409 children with available developmental data. Among them, 1,095 children, representing approximately 0.6% of the cohort, had documented prenatal metformin exposure.

How Researchers Measured Development

Investigators used the Australian Early Development Census, a standardized national assessment completed during children's first year of full-time school.

The assessment covered five important developmental domains:

• Physical health and well-being
• Social competence
• Emotional maturity
• Language and cognitive skills
• Communication skills and general knowledge

Children scoring below the 10th percentile in at least two domains were classified as developmentally vulnerable.

This approach allowed researchers to examine several aspects of early childhood development rather than relying on a single academic or behavioral measure.

Key Findings From the 177,409-Child Cohort

Developmental vulnerability occurred in 18.2% of metformin-exposed children compared with 13.9% of unexposed children.

Initially, these figures suggested a higher prevalence among exposed children. However, differences between maternal populations can influence developmental outcomes independently of medication exposure.

Therefore, researchers adjusted for measured confounding factors using statistical methods designed to improve comparisons between groups.

After adjustment, metformin exposure was not associated with developmental vulnerability. The adjusted relative risk was 0.97, with a 95% confidence interval of 0.74 to 1.29.

Furthermore, investigators found no significant adjusted associations across any of the five individual developmental domains.

A separate analysis examining first-trimester exposure also found no significant association with developmental vulnerability.

Overall, these findings provide reassuring evidence about early childhood development following prenatal metformin exposure.

Understanding the Study's Limitations

Although the study provides valuable evidence, its observational design cannot establish that metformin has no developmental effects.

First, prescription records documented medication dispensing rather than confirmed ingestion. Researchers therefore could not establish precisely how consistently each pregnant patient took metformin.

Second, only 1,095 children had documented prenatal exposure, despite the large overall cohort. This relatively small exposed group limits the study's ability to detect uncommon outcomes or modest differences in risk.

Importantly, the confidence interval does not exclude every potentially meaningful increase or decrease in developmental risk.

Third, residual confounding remains possible even after statistical adjustment. Maternal diabetes severity, metabolic health, access to healthcare, and other influences may affect childhood development.

Additionally, the assessment measured broad developmental abilities at school entry. It did not provide detailed diagnostic testing for conditions such as autism spectrum disorder or attention-deficit/hyperactivity disorder.

The findings also cannot establish whether prenatal exposure affects adolescent health, adult metabolism, or later cognitive outcomes.

Previous research has raised questions about childhood body composition following metformin exposure. Therefore, normal developmental assessment results should not be interpreted as evidence that all long-term health outcomes are unaffected.

Implications for Diabetes Care During Pregnancy

For clinicians, the latest findings add useful evidence to discussions about prenatal metformin exposure. Nevertheless, treatment decisions must consider both maternal glucose management and potential fetal outcomes.

The American Diabetes Association's 2026 Standards of Care continue to recommend insulin as the preferred medication for managing gestational diabetes and type 2 diabetes during pregnancy.

Metformin is not recommended as a first-line medication because it crosses the placenta and may not provide sufficient glucose control for every patient.

However, some patients may face barriers to insulin treatment, including cost, difficulty administering injections, or challenges following complex treatment schedules.

In selected circumstances, clinicians may consider metformin after discussing its potential benefits, limitations, and uncertainties.

Earlier research, including the MiTy trial reviewed by Diabetes in Control, also explored maternal and neonatal outcomes when metformin was added to insulin therapy.

Still, short-term pregnancy benefits and longer-term offspring outcomes represent different clinical questions.

When counseling patients, clinicians can explain that the new study found no significant association with developmental vulnerability at ages 4 to 6 after adjustment. At the same time, it does not prove that every aspect of long-term development is unaffected.

Shared decision-making should consider glucose levels, pregnancy complications, medication tolerance, treatment preferences, and current clinical guidelines. Patients should not discontinue prescribed treatment without consulting their pregnancy care team.

For additional individualized guidance, patients can connect with healthcare professionals through Healthcare.pro.

Conclusion

The latest research on metformin exposure during pregnancy provides encouraging evidence about children's developmental outcomes and offers useful insights for diabetes care teams.

Among more than 177,000 children, prenatal metformin exposure was not associated with increased developmental vulnerability at ages 4 to 6 after adjustment for measured confounding factors.

However, the findings do not establish complete long-term safety, and questions about later metabolic, physical, and neurodevelopmental outcomes remain.

For now, clinicians should incorporate these results into balanced patient counseling while continuing to follow established diabetes pregnancy management recommendations.

Frequently Asked Questions

1. Does taking metformin during pregnancy cause developmental delays?

The new cohort study found no significant association between prenatal metformin exposure and developmental vulnerability at ages 4 to 6 after adjustment. However, observational findings cannot completely rule out potential risks.

2. Does metformin cross the placenta during pregnancy?

Yes. Metformin crosses the placenta and can reach the developing fetus. This is an important reason researchers continue investigating its long-term effects.

3. Is metformin safer than insulin for gestational diabetes?

Not necessarily. Current ADA guidelines recommend insulin as the preferred medication for gestational diabetes. Metformin may be considered in selected circumstances following individualized clinical assessment.

4. Does prenatal metformin exposure affect childhood learning or behavior?

Researchers found no significant adjusted association with the measured language, cognitive, communication, emotional, or social developmental domains. However, the study did not evaluate every learning or behavioral disorder.

5. What do researchers still need to learn about children's development after prenatal metformin exposure?

Additional studies should examine larger exposed populations, follow children through adolescence, and assess cognitive function, metabolic health, body composition, and other longer-term outcomes.

This content is not medical advice. For any health issues, always consult a healthcare professional. In an emergency, call 911 or your local emergency services.