Lyme Disease and Pregnancy Outcomes

Lyme disease and pregnancy outcomes remain an important concern for women diagnosed with infection during pregnancy. A study by researchers in Slovenia examined whether early Lyme disease affects pregnancy outcomes in women treated for erythema migrans.

In their article, “Course and Outcome of Erythema Migrans in Pregnant Women,” Maraspin and colleagues describe the pregnancy course and outcomes for 304 women who were treated with antibiotics for early Lyme disease.

All of the women were diagnosed with Lyme disease based on the presence of an erythema migrans (EM or bull’s-eye) rash. They were evaluated before antibiotic treatment was initiated and then followed at 2 weeks and again at 2, 6, 12, and 18 months.

At the first visit, the majority of patients (98%) were treated with IV ceftriaxone (2 g once daily). The remaining patients received either IV penicillin G (10,000,000 units twice daily) or oral phenoxymethylpenicillin (1 g three times daily). Patients received a 14-day course of antibiotics.

Pregnancy outcomes following Lyme disease treatment

The outcome of pregnancy was unfavorable in 13.8% (42/304) of patients, the authors report.

These unfavorable outcomes included 22 preterm births, 10 fetal or perinatal deaths, and 15 congenital anomalies. However, several mothers had other possible explanations for these outcomes.

The authors concluded that the rate of unfavorable outcomes among women treated for early Lyme disease was not significantly different from rates seen in the general population. Still, they noted that women who developed erythema migrans early in pregnancy may have a slightly higher risk of unfavorable outcomes.

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The researchers concluded that pregnancy outcomes were generally favorable following treatment with a two-week course of antibiotics.

Meanwhile, another study involving approximately 2,000 women with a history of Lyme disease did not demonstrate an increased risk of fetal death, decreased birth weight, or shorter gestational length at delivery. ²

However, in the same study of 2,000 women, a history of a tick bite within three years before conception was associated with congenital defects.

Clinical perspective

The Maraspin study focused on women diagnosed with early Lyme disease. The authors did not follow the 262 women who had favorable pregnancy outcomes for possible long-term developmental issues in their children. They also did not describe outcomes for women who were not treated for early Lyme disease.

Because the findings were based on a case series, additional research is needed to determine whether Lyme disease might contribute to preterm birth, fetal loss, or congenital anomalies in some pregnancies.

Symptoms of Lyme disease during pregnancy may overlap with the broader patterns described in the Lyme disease symptoms guide, and understanding how infection affects different populations—including children and pregnant women—remains an important part of the ongoing discussion about persistent Lyme disease mechanisms.

Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention