Examination for influenza IgA and IgM antibodies in pregnancies associated with fetal neural-tube defects.

Early antenatal serum specimens were collected from 25 women who subsequently gave birth to infants with anencephaly or spina bifida. Fluorescent-antibody test for influenza-specific IgA and IgM antibodies, although shown to be reliable for the detection of recent influenzal infection, failed to demonstrate such infection in any of these women. Early infection was detected in one of 50 control women who gave birth to a healthy infant. The results indicate that influenzal infection in pregnancy was not a major cause of neural-tubal defects in Oxford during 1972--76, if a cause at all.