Reducing the Risk of Birth Defects Associated with Maternal Influenza: Insights from a Hungarian Case-Control Study

Influenza viruses can cause several complications during pregnancy. Therefore, we aimed to investigate the effects of influenza on the development of congenital abnormalities (CAs) by analyzing the database of the Hungarian Case-Control Surveillance of Congenital Abnormalities (HCCSCA). In our multicenter, case-control, population-based study, we processed clinician-reported outcomes and diagnoses collected in the HCCSCA. The case group included newborns with different non-chromosomal birth defects, while the controls were newborns without CAs. Maternal influenza, as a risk factor for CAs, was analyzed by using a logistic regression model and odds ratios with 95% confidence intervals (CIs). Our results showed that maternal influenza in the first trimester was associated with increased odds of developing non-chromosomal CAs (OR: 1.41, CI: 1.28-1.55). There were increased odds of neural tube defects (OR: 2.22, CI: 1.78-2.76), orofacial clefts (OR: 2.28, CI: 1.87-2.78), and congenital heart defects (OR: 1.28, CI: 1.10-1.49) after influenza infection. In all cases, we found a protective effect of folic acid supplementation in the first trimester. In summary, the odds of non-chromosomal birth defects are higher after maternal influenza in the first trimester, and folic acid or pregnancy vitamin supplementation and antipyretic therapy may reduce the effect of maternal influenza during the first trimester.