Maternal influenza-like illness, medication use during pregnancy and risk of congenital heart defects in offspring.

Objective: To evaluate the association between maternal influenza and congenital heart defects (CHDs), and whether the use of traditional Chinese medicine (TCM) or Western medicine (antibiotics, antipyretic-analgesic drugs) modified this association.

Methods: We analysed 294 fetuses with CHDs and 416 control fetuses without any abnormalities identified from February 2010 through October 2011 in this hospital-based case-control study. Participating mothers were interviewed to determine whether they had been infected with "influenza" during the early pregnancy period or had used any medicine (TCM, Western medicine) to treat influenza. A logistic regression model was used to calculate ORs and 95% CIs while controlling for potential confounders.

Results: There were significant associations between maternal influenza and CHDs in the aggregate (AOR, 1.60; 95%CI, 1.12 to 2.28) and specific subtypes, namely septal defects (AOR, 2.12; 95%CI, 1.38 to 3.26) and conotruncal defects (AOR, 1.60; 95%CI, 1.01 to 2.51). Maternal medication use (i.e. TCM or Western medicine) in the setting of influenza tended to decrease these associations.

Conclusions: Maternal influenza during second-third months of pregnancy increased the risk for CHDs, with septal defects and conotruncal defects in particular being observed. The use of medication for influenza might attenuate such associations.