Tick bites during pregnancy. A perspective.
One would think that there would be substantial scientific evidence indicating the best treatment options for pregnant women who have a tick bite. Unfortunately, there is not. In their article, Smith and colleagues address the question: “If the health care provider decides to recommend antibiotic prophylaxis for a pregnant woman with a tick bite, what are the choices?” 
The authors cite studies with “high-level evidence” recommending prophylaxis treatment of tick bites during pregnancy with a single dose of 200 mg of doxycycline. The risk, they say, to the unborn baby is low.
“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
“However, extensive literature on and experience with doxycycline use in pregnancy has demonstrated no such risk,” they claim.
The authors cite a systematic review describing the safety of doxycycline in treating tick bites during pregnancy and in early childhood. The study found:
- no teratogenicity during pregnancy
- no permanent tooth staining from in utero exposure or use by children under 8 years old
- no hepatotoxicity
- no permanent inhibitory effects on bone growth
The authors argue that there is “high-level evidence” to support the use of a single 200 mg dose of doxycycline for tick bites during pregnancy. However, the evidence they cite is not high-level. Instead, the data is from a small Meta-Analysis study.
Furthermore, there is no evidence that a single 200 mg dose of doxycycline will prevent other manifestations of Lyme disease, such as heart block, 7th nerve palsy, Lyme arthritis, Lyme encephalopathy, or Neuropsychiatric Lyme disease.
Nor is there evidence that a single 200 mg dose of doxycycline will prevent tick-borne co-infections. One case study reported two newborns who contracted Babesia in utero, even though the mother was being treated for Lyme disease in her third trimester.
Editor’s Note: When a pregnant woman has been bitten by a tick, I always prescribe 4 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 re-evaluate with follow-up.
I do not agree with the authors in presenting a single 200 mg dose of doxycycline as a high-level treatment recommendation. It is not.
- 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.
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