A serological survey over a 1-year period of 1416 mothers at delivery and their 1434 offspring for the presence of anti-Borrelia burgdorferi antibodies revealed a prevalence of 0.85%. Clinically active
Lyme disease during pregnancy was found in 1 of these 12 women with elevated titres and the child was born with a ventricular septal defect. Of six affected children, two had hyperbilirubinaemia, one muscular hypotonia, one was underweight for gestational age, one was macrocephalic, and one had supraventricular extrasystoles. Anomalous findings could not be attributed to B. burgdorferi due to a lack of serological evidence of intrauterine infection. Our data do not imply the need for serological screening in pregnancy, however, the importance of recognition and treatment of
Lyme disease in pregnancy is emphasized.