For decades, pregnant women have faced a difficult decision when they get sick: treat the infection and risk harming their baby, or skip the medication and hope for the best. A new, large-scale study brings welcome news for expectant mothers and their doctors. Researchers have found that a widely prescribed antibiotic called azithromycin does not appear to raise the risk of neurodevelopmental disorders in children when used during pregnancy.

This finding is particularly important because infections during pregnancy are common, and untreated infections can themselves pose serious risks to both mother and child. The study, published recently in the journal JAMA Network Open, helps fill a gap in medical knowledge about medication safety during pregnancy.

What the Study Found

The research team, led by Dr. Xuerong Wen from the University of Rhode Island, analyzed health records from over 15,000 mother-infant pairs. The children were followed for an average of 5.5 years after birth. The results were clear: exposure to azithromycin at any point during pregnancy was not linked to a higher risk of neurodevelopmental disorders when compared to no antibiotic use or use of other antibiotics.

This means that for conditions like attention deficit-hyperactivity disorder (ADHD), autism spectrum disorder, speech and language disorders, developmental coordination disorder, and behavioral disorders, the children whose mothers took azithromycin were no more likely to be diagnosed than those whose mothers did not take the drug.

A Surprising Protective Effect

Perhaps the most unexpected finding came when researchers looked specifically at women who took azithromycin late in pregnancy—defined as after 20 weeks of gestation up until delivery. In this group, the antibiotic was actually linked to a lower risk of certain neurodevelopmental problems.

• Overall neurodevelopmental disorders: Compared to women who took other antibiotics, those who used azithromycin late in pregnancy had a 31% lower risk of their child developing any neurodevelopmental disorder.
• Speech and language disorders: The risk was 41% lower compared to other antibiotics, and 39% lower compared to no antibiotics at all.
• Autism spectrum disorder: When azithromycin was used at any time during pregnancy, the risk of autism was 63% lower compared to no antibiotic exposure. However, the researchers caution that the number of autism cases in the study was very small, so this finding could be due to random chance.

Dr. Wen admitted she was surprised by these results. “We’ve seen that azithromycin has been going down in use,” she noted, partly because of concerns over antibiotic resistance. But she added, “We don’t need to totally give up on this drug.”

Why Might Azithromycin Be Protective?

The researchers believe the key may lie in azithromycin’s unique properties. Unlike many antibiotics that only kill bacteria, azithromycin also has strong anti-inflammatory effects. When a pregnant woman is sick, her body’s immune response—inflammation—can sometimes affect the developing fetus through the placenta.

Dr. Dani Dumitriu, a newborn medicine specialist at Columbia University who was not involved in the study, explained that there is growing evidence that maternal inflammation during illness can influence fetal brain development. “That makes it incredibly important to build an empirical basis for what medications we prescribe to pregnant women,” she said.

Azithromycin may help by dampening that harmful inflammation while also fighting the infection. The protective effect was strongest late in pregnancy, which makes biological sense. “This is when brain development is most rapid,” Dr. Dumitriu noted. “Further strengthening this hypothesis is the fact that this protection is most observable with antibiotic use late in pregnancy.”

What This Means for Expectant Mothers

For pregnant women, this study offers a measure of relief. Infections such as urinary tract infections, respiratory infections, and certain sexually transmitted infections are common during pregnancy. If left untreated, they can lead to serious complications including preterm labor, low birth weight, and even miscarriage.

The study’s most important message, according to Dr. Dumitriu, is the lack of risk to the fetus. “Azithromycin and other antibiotics may dampen maternal inflammation and confer protection to the growing fetus,” she said.

However, experts stress that pregnant women should not take antibiotics without a doctor’s prescription. The decision to use any medication during pregnancy should always involve a careful discussion between the patient and her healthcare provider, weighing the risks of the infection against the risks of the treatment.

How the Study Was Conducted

The research team used health insurance claims data from commercially insured women in the northeastern United States. The study included 15,527 mother-infant pairs with a live birth between December 2012 and December 2023. The mothers were either prescribed at least one antibiotic during pregnancy or had no antibiotic exposure at all. The average age of the mothers was 32.4 years.

Among the study population:

• 4.8% of mother-infant pairs were exposed to azithromycin
• 19.8% were exposed to other antibiotics
• 75.4% had no antibiotic exposure during pregnancy

The primary outcome the researchers tracked was a combined measure of several neurodevelopmental disorders, including ADHD, autism, speech and language disorders, developmental coordination disorder, and behavioral disorders.

Important Limitations to Consider

While the results are encouraging, the study has some limitations that readers should understand. First, because it was an observational study (not a randomized controlled trial), there may be other factors that influenced the results. For example, women who took azithromycin might have been healthier in other ways, or might have had different genetic backgrounds, that could explain the lower risks seen.

Second, the study only included women with commercial health insurance in the Northeast. This means the findings may not apply to women who are uninsured or who have public insurance like Medicaid. The researchers also only included live births, which could introduce a form of selection bias.

Finally, the number of autism cases in the study was quite low, which is why the apparent protective effect for autism should be interpreted with caution. Dr. Wen warned that the finding “may be attributable to chance.”

Practical Takeaways for Readers

So what should you do if you are pregnant and develop an infection? Here are some key points to keep in mind:

• Don’t ignore infections: Untreated infections during pregnancy can be dangerous for both you and your baby. Always report symptoms like fever, pain, or unusual discharge to your healthcare provider.
• Talk to your doctor about antibiotic options: This study suggests that azithromycin is a safe choice for treating infections during pregnancy, especially in the later stages. But your doctor may recommend other antibiotics depending on the type of infection you have.
• Follow your prescription exactly: If your doctor prescribes an antibiotic, take the full course as directed. Do not stop early, even if you feel better, as this can contribute to antibiotic resistance.
• Keep perspective: The overall risk of neurodevelopmental disorders in children is low, regardless of antibiotic use. This study adds to a growing body of evidence that treating infections during pregnancy is generally safe and beneficial.

What Experts Are Saying

Medical professionals have welcomed the study as an important step forward. Dr. Dumitriu emphasized that the most critical finding is the absence of harm. “This study’s most important finding is the lack of risk to the fetus,” she said.

Dr. Wen echoed that sentiment, noting that azithromycin has been falling out of favor due to fears about antibiotic resistance. But she believes the drug still has an important role in pregnancy care. “Prescribed with caution, especially in the later stages of pregnancy, clinicians could think about using azithromycin,” she said.

The study also highlights a broader principle in maternal-fetal medicine: treating the mother’s illness often benefits the baby. Inflammation from an infection can travel through the placenta and affect the developing fetal brain. By controlling that inflammation, antibiotics like azithromycin may do more than just cure the infection—they may actively protect the baby’s developing nervous system.

The Bottom Line

For pregnant women and their doctors, this study provides strong reassurance that azithromycin does not increase the risk of neurodevelopmental disorders in children. In fact, when used later in pregnancy, it may even offer some protection. While more research is needed to confirm these findings and understand the underlying mechanisms, the message for now is clear: when a bacterial infection strikes during pregnancy, treating it with azithromycin appears to be a safe and potentially beneficial choice.

As always, any medication use during pregnancy should be guided by a healthcare professional who can weigh the specific risks and benefits for your individual situation. But this new evidence should help ease the minds of millions of expectant mothers who need antibiotics to stay healthy during pregnancy.

Source: MedPage Today