Good News for Parents-to-Be: Infections Do Not Affect the baby’s Intelligence

Pneumonia, urinary tract infections, and other common infections during pregnancy do not appear to impact a child's brain development or cognitive abilities later in life. This is the conclusion of a Danish registry-based study recently published in the respected journal PLOS Medicine.

In this large-scale study, researchers analyzed data from more than 270,000 children born in Denmark between 1996 and 2003. They compared school grades in Danish and mathematics from the 9th-grade exams as well as intelligence test scores from military conscription assessments among young men.

The study found no significant differences in the children’s academic or cognitive outcomes - whether their mothers had been hospitalized with infections or received antibiotic treatment during pregnancy.

“The findings suggest that common infections and their treatment with antibiotics do not have any notable negative effects on fetal brain development,” says physician and lead author Anders Husby from the Statens Serum Institut.

“Furthermore, we found no evidence that there are specific, particularly vulnerable periods during pregnancy when such infections might have a greater impact,” he adds.

Sibling Comparisons Strengthen the Study

A key strength of the study is that researchers not only compared children across the general population but also examined siblings within the same families. This approach allowed them to control for genetic and social factors that can influence cognitive development.

“When we compare full siblings, we automatically account for many confounding factors, such as upbringing, parental education, and genetic background,” explains co-author Mads Melbye, Research Director at the Danish Cancer Society.

“From a global perspective, it’s quite unique to be able to conduct this kind of analysis across an entire population.”
Infections were identified using data on antibiotic prescriptions and hospital admissions during pregnancy. The results were then matched with the children's academic performance and intelligence scores.

Reassuring Findings – But Medical Advice Still Crucial

The findings offer reassurance to expecting parents who may worry about the effects of infections or medication during pregnancy.

“The study supports that the typical antibiotics we use to treat infections in pregnant women are safe,” says Anders Husby. He adds:

“At the same time, it’s important to emphasize that pregnant women should still consult a doctor if they experience signs of infection. Untreated, severe infections can lead to preterm birth, which poses risks for the baby.”

The study was conducted in collaboration between the Statens Serum Institut and the Danish Cancer Society, with support from the Lundbeck Foundation and the Health Foundation.

Read the full study published in PLOS Medicine.