Tick Bites During Pregnancy: A Clinical Perspective

Tick bites during pregnancy raise important concerns about Lyme disease and other tick-borne infections. Some authors recommend prophylaxis with a single 200 mg dose of doxycycline after a tick bite, suggesting the risk to the unborn baby is low.

However, the evidence supporting this recommendation remains limited, and treatment decisions during pregnancy require careful consideration of both maternal and fetal risks.

Smith and colleagues cite studies they describe as “high-level evidence” recommending prophylaxis treatment of tick bites during pregnancy with a single 200 mg dose of doxycycline.

“Previously, doxycycline was avoided in pregnancy and in children under 8 years of age because of concerns about adverse effects similar to those of tetracyclines, specifically staining of teeth and delayed bone growth,” the authors write.

READ MORE: Pregnancy and Lyme Disease

The authors argue that extensive literature and clinical experience with doxycycline use during pregnancy demonstrate no such risk.

Evidence Cited for Doxycycline in Pregnancy

The authors reference a systematic review examining the safety of doxycycline during pregnancy and in early childhood. The study reported:

No evidence of teratogenicity during pregnancy
No permanent tooth staining from in-utero exposure or use in children under 8 years of age
No hepatotoxicity
No permanent inhibitory effects on bone growth

Based on these findings, the authors suggest that a single 200 mg dose of doxycycline may be appropriate prophylaxis after a tick bite during pregnancy.

Limitations of the Evidence

However, the evidence cited for this recommendation is not truly “high-level.” Much of the supporting data comes from relatively small studies and meta-analysis reviews rather than large prospective clinical trials.

More importantly, there is no clear evidence that a single 200 mg dose of doxycycline prevents the broader manifestations of Lyme disease.

These complications may include:

Lyme carditis and heart block
7th cranial nerve palsy
Lyme arthritis
Lyme encephalopathy
Neuropsychiatric Lyme disease

There is also no evidence that a single prophylactic dose prevents tick-borne co-infections.

For example, one report described two newborns who contracted Babesia in utero even though the mother was receiving treatment for Lyme disease during her third trimester.

Clinical Perspective

Editor’s Note: When a pregnant woman has been bitten by a tick, I typically prescribe four weeks of amoxicillin or azithromycin, erring on the side of caution to protect the fetus. I also work closely with the patient’s OB/GYN and reassess the patient with follow-up evaluation.

While some authors suggest a single 200 mg dose of doxycycline as prophylaxis after a tick bite, I believe the current evidence supporting that approach remains limited. Given the potential consequences of untreated infection during pregnancy, a more cautious treatment strategy may be appropriate.

Management decisions should always be individualized and coordinated with the patient’s obstetric care team.

Tick bites during pregnancy are one of several concerns discussed in our guide to Lyme disease during pregnancy, including congenital infection and management of tick-borne co-infections.

References

Smith GN, Moore KM, Hatchette TF, Nicholson J, Bowie W, Langley JM. Committee Opinion No. 399: Management of Tick Bites and Lyme Disease During Pregnancy. J Obstet Gynaecol Can. 2020;42(5):644-653.

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