(HealthDay News) — Maternal influenza vaccination is not associated with increased risk of congenital anomalies, according to a review published online October 7 in Obstetrics & Gynecology.

Konstantinos A. Polyzos, MD, from Iaso General Hospital in Greece, and colleagues conducted a systematic review on maternal influenza vaccination and the risk for congenital malformation. The risk of congenital anomalies after vaccination was reviewed using data from 15 studies (14 cohorts and one case-control study); eight studies reported on first-trimester immunization.

The researchers found that risk for congenital anomalies was similar for vaccinated and unvaccinated (events per vaccinated versus unvaccinated, 2.6 vs. 3.1% in the cohort studies; 37.3 vs. 41.7% in the case-control study). Events per vaccinated versus unvaccinated were 5.4 vs. 3.3% in the studies that reported on first-trimester vaccination. There was no correlation between congenital defects and influenza vaccination in any trimester (odds ratio [OR], 0.96; 95% confidence interval [CI], 0.86–1.07) or in the first trimester (OR, 1.03; 95% CI, 0.91–1.18). With respect to major malformations, there was no increased risk after immunization in any trimester (OR, 0.99; 95% CI, 0.88–1.11) or in the first trimester (OR, 0.98; 95% CI, 0.83–1.16).

“This systematic review did not indicate an increased risk for congenital anomalies after maternal influenza immunization, adding to the evidence base on the safety of influenza vaccination in pregnancy,” the authors write.

One author disclosed ties to the pharmaceutical industry.

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