Viral infections during pregnancy raise several clinical challenges, including birth defects in the offspring. Thus, this systematic review and meta-analysis aims to prove and highlight the risk of birth defects after first-trimester maternal influenza infection. Our systematic search was performed on 21 November 2022. Studies that reported maternal influenza infection in the first trimester and non-chromosomal congenital abnormalities were considered eligible. We used odds ratios (OR) with 95% confidence intervals (CIs) to measure the effect size. Pooled ORs were calculated with a random effects model. Heterogeneity was measured with I² and Cochran’s Q tests. We found that first-trimester maternal influenza was associated with increased odds of developing any type of birth defects (OR: 1.5, CI: 1.30–1.70). Moreover, newborns were more than twice as likely to be diagnosed with neural tube defects (OR: 2.48, CI: 1.95–3.14) or cleft lip and palate (OR: 2.48, CI: 1.87–3.28). We also found increased odds of developing congenital heart defects (OR: 1.63, CI: 1.27–2.09). In conclusion, influenza increases the odds of non-chromosomal birth defects in the first trimester. The aim of the present study was to estimate the risk of CAs in the offspring of mothers affected by first-trimester influenza infection.

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.

Influenza virus can cause several complications during pregnancy. Therefore, we aimed to inves-tigate the effects of influenza on the development of congenital abnormalities (CAs) by analyzing the database of the Hungarian Case-Control Surveillance of Congenital Abnormalities (HCCS-CA). 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 dif-ferent non-chromosomal birth defects, while controls were newborns without CAs. Maternal in-fluenza, as a risk factor for CAs, was analyzed by using a logistic regression model and odds ra-tios 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 tri-mester. The odds of non-chromosomal birth defects are higher after maternal influenza in the first -trimester. Folic acid or pregnancy vitamin supplementation and antipyretic therapy may reduce the effect of maternal influenza during the first trimester.