Lyme disease during pregnancy

By trimester

Weeks 1–13

1st trimester

An expanding erythema migrans rash can appear three to 30 days after a tick bite and may establish early Lyme disease before antibodies are detectable. Photograph the rash and contact a clinician promptly rather than waiting for a blood test to turn positive.

Weeks 14–27

2nd trimester

Joint swelling, facial droop, severe headache, palpitations, dizziness, or shortness of breath can reflect disseminated Lyme disease and needs timely assessment. Antibiotic choice depends on the manifestation, allergies, and pregnancy-specific risk discussion.

Weeks 28–birth

3rd trimester

A suspected new infection late in pregnancy still needs prompt care. Pregnancy outcome evidence is limited, so the obstetric and infectious-disease teams can individualize follow-up according to the maternal manifestation, response to care, fetal status, and other pregnancy factors.

What does the evidence show for lyme disease?

• CDC describes erythema migrans as an expanding rash that begins three to 30 days after a tick bite, occurs in about 70% to 80% of infected people, and does not always look like a classic bull's-eye. 1
• CDC recommends FDA-cleared two-step antibody testing when laboratory testing is indicated. Antibody tests can be falsely negative during the first weeks, particularly when erythema migrans is present, and can remain positive for months or years after infection is gone. 2
• CDC's pregnancy fact sheet says placental infection has been reported and fetal spread is possible but rare. It reports no increased adverse-birth-outcome risk with appropriate antibiotic care, while acknowledging that child developmental outcomes after gestational infection have not been studied. 3
• Current CDC clinical guidance says likely erythema migrans in an endemic exposure setting should receive prompt care even if early serology is ordered, because tests may still be negative. Regimen selection must account for pregnancy, medical history, allergies, and the clinical manifestation. 4
• A systematic review found inconsistent epidemiologic evidence about adverse birth outcomes and only limited evidence for transplacental transmission. Eight exposed-versus-unexposed studies reported no outcome difference, while an indirect comparison associated maternal antibiotic care with fewer adverse outcomes; confounding and heterogeneous exposure definitions limit causal conclusions. 5

When should I call my provider about lyme disease?

Seek urgent assessment for Lyme disease concerns with facial droop, severe headache or neck stiffness, fainting, chest pain, palpitations, an irregular heartbeat, shortness of breath, new weakness, numbness, or tingling. During pregnancy, fever with an expanding rash also deserves prompt contact rather than waiting for a routine visit. Call the obstetric team immediately for reduced fetal movement, bleeding, leaking fluid, or regular preterm contractions. None of these lists replace your own judgment: if this symptom worries you, that on its own is enough reason to check in with your healthcare provider.