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.
