Treatment of erythema migrans in pregnancy.

The course of the illness and the outcome of pregnancy were investigated in a prospective study of 58 consecutively enrolled pregnant women with typical erythema migrans at the University Medical Centre of Ljubljana, Slovenia. Thirteen patients (22.4%) acquired borrelial infection in the first trimester of pregnancy, 27 (46.6%) in the second trimester, and 18 (31%) in the third trimester. All patients were treated for 14 days: 2 (3.4%) with phenoxymethylpenicillin (1 million IU thrice per day), 3 (5.2%) with benzylpenicillin (10 million units twice per day), and 53 (91.4%) with ceftriaxone (2 g daily). For 51 of the 58 women (87.9%), the pregnancies were normal and the infants were born at term, were clinically healthy, and had normal psychomotor development. Of the remaining 7 pregnancies, 1 ended with a missed abortion and 5 with preterm birth; 1 of the preterm babies had heart abnormalities. One child born at term was found to have urologic abnormalities at 7 months of age. A causal relationship between borrelial infection and fetal adverse effects has not been proven, and for at least some such cases a reasonable explanation (not associated with Lyme borreliosis) was found.