There are conflicting studies on the effects of Lyme disease upon pregnancy & the subject remains insufficiently studied.  Individual case reports exist of adverse outcomes & gestational transmission.  There is also supporting evidence that if Lyme is treated with antibiotics during pregnancy, the chance of complications is lower than in untreated mothers.  Some larger serological & epidemiological studies that focused on treated pregnancies have demonstrated no statistical effect or causal connection to a particular adverse outcome.  These larger studies support the idea that antibiotic treatment is essential to reducing the risks of Lyme disease to the fetus during pregnancy.  Also note, it is unclear if Lyme disease & other tick-borne diseases could be transferred to a baby via the mother's infected breastmilk.  The complications from untreated Lyme disease can include:

  • Miscarriage or stillbirth
  • Congenital heart defects
  • Genitourinary defects
  • Neurological defects
  • Other less common anomalies (orthopedic, ophthalmic, etc.)
  • Risk of Lyme disease & co-infection transmission through the placenta

The summary of outcomes in documented cases of congenital Lyme disease is as follows:

  • In mothers with active Lyme disease,

    • Treated: 14.6% of the pregnancies involved symptoms in fetus (including fatality)
    • Untreated: 66.7% of the pregnancies involved symptoms in fetus (including fatality)
    • Unknown as to treatment: 30.3% involved symptoms in fetus (including fatality)

  • Specific adverse outcomes included:

    • cardiac 22.7%,
    • neurological 15.2%,
    • orthopedic 12.1%,
    • ophthalmic 4.5%,
    • genitourinary 10.6%,
    • miscellaneous anomalies 12.1%,
    • 2nd trimester miscarriage 12.1%.

  • Highest rate of adverse outcome (72.7%) in women with infection acquired prior to or during first trimester.


The first reported case of congenital Lyme disease was documented in 1985.
Maternal-fetal Transmission of the Lyme Disease Spirochete, Borrelia Burgdorferi, Annals of Internal Medicine 103:67-69, 1985, P.A. Schlesinger et al

  • Woman in Wisconsin, USA was bitten during her first trimester & developed EM & typical Lyme disease symptoms
  • Did not receive medical treatment
  • Gave birth to a baby boy at 35 weeks
  • Baby died 39 hours later from congestive heart failure
  • At autopsy there were several major defects of the heart
  • Lyme disease spirochetes were found in the baby’s spleen, kidneys, bone marrow & heart at autopsy
  • The mother tested positive for Lyme disease after pregnancy.

In 1986, a case was reported by Weber.
Weber, K, Bratzke, HJ, Neubert, U, Wilske, B, Duray, PH. Borrelia burgdorferi in a newborn despite oral penicillin for Lyme borreliosis during pregnancy. Pediatr Infect Dis J 1988; 7:286–289

  • Mother bitten by multiple ticks during her first trimester
  • Developed EM rash several weeks later
  • Treated with a “standard” course of oral penicillin for seven days, three times a day
  • Baby delivered at term & appeared normal
  • During the next 23 hours the baby developed breathing problems & died
  • Autopsy showed brain hemorrhages
  • Spirochetes compatible with Borrelia burgdorferi in the brain & the liver
  • Mother’s blood initially tested negative for antibodies to the Lyme spirochete; at a later date her frozen blood tested positive for IgM antibodies using the ELISA test.

Another case was reported in 1987 in Utah.
Stillbirth following maternal Lyme disease, MacDonald AB, Benach JL, Burgdorfer W., N Y State J Med. 1987 Nov; 87(11):615-6

  • Woman infected in her first trimester of pregnancy, but not diagnosed or treated
  • Had EM rash & joint swelling
  • Went into labour at full term
  • Baby’s heartbeat already undetectable, baby dead at birth
  • Autopsy revealed a hole in the wall of the heart which separates the two main pumping chambers
  • Lyme bacterium cultured from the baby’s liver, brain, heart, adrenal gland & placenta
  • Mother was tested for Lyme antibodies at three different laboratories & the result was positive from two of them. She tested negative for syphilis.

The medical report stated:
“Transmission of the spirochete Borrelia Burgdorferi from mother to fetus during the first trimester of pregnancy was followed by overwhelming spirochetosis in the fetus.”

Markowitz published a study of Lyme & pregnancy in 1986.
Markowitz LE, Steere AC, Benach JL, et al. Lyme disease during pregnancy. JAMA.(1986); 255(24), 3394-6

  • Nineteen patients infected during pregnancy
  • Five had adverse outcomes (one fetal death at 20 weeks, high bilirubin level in a four-week premature baby, webbed toes, blindness & developmental delay, & a newborn rash)
  • Thirteen of the nineteen had received antibiotics
  • Authors concluded that there was no proof that Lyme disease was responsible for the adverse outcomes since all of them were dissimilar
  • Consensus that this was an abnormally high frequency of adverse outcomes, & that pregnant women with diagnosed Lyme disease should be treated immediately with penicillin.

Williams & colleagues conducted a study in a Lyme-endemic area in New York of umbilical cord blood.
Williams, CL, Strobino, B, Weinstein, A, Spierling, P, Medici, F. Maternal Lyme disease and congenital malformations: a cord blood serosurvey in endemic and control areas. Paediatr Perinat Epidemiol 1995; 9:320–330

  • Of 255 infants tested, 10.2% had detectable antibody to the Lyme disease spirochete; Of 166 infants born in a non-endemic area, 2.4% had detectable antibodies
  • Birth defects did not differ significantly between the two groups
  • First group tended to be lower birth weight & smaller, with more jaundice
  • Authors concluded that these differences were not significant

A glaring flaw in this study is that it only included live births. Since miscarriages, stillbirth & perinatal infant deaths were not included, the possibility of congenital defects possibly associated with Lyme & incompatible with life are not included!

Dr. Andrea Dlesk, of the Marshfield clinic in Wisconsin, studied 143 healthy pregnant women.

  • Lyme disease serologic tests were obtained on initial & postpartum visits
  • 116 women had completed their pregnancies & 12 had miscarried, one of whom tested positive
  • Of the 104 women who did not miscarry, 13 women tested positive for Lyme disease
  • Conclusion: healthy women who test positive for Lyme disease are at no increased risk for miscarriage

This study is flawed because there is no autopsy data on the 12 miscarriages. In the 11 seronegative mothers who miscarried, Lyme disease may have been present & may have caused defective fetuses.

In 1988, Carlomango studied 49 women who had either a 1st or 2nd-trimester spontaneous abortion.
Carlomagno G; Luksa V; Candussi G; Rizzi GM; Trevisan G Acta Eur Fertil 1988 Sep-Oct;19(5):279-81 Dept. of Obstetrics and Gynecology, University of Trieste School of Medicine. Lyme Borrelia positive serology associated with spontaneous abortion in an endemic Italian area

  • Six (6) of them (12.2%) tested positive for Lyme disease
  • 3 of 49 women who delivered at term tested positive
  • Authors concluded that there was no statistical significance between the two groups.

In 1988, Nadal surveyed 1,416 women & their 1,434 infants at delivery for the presence of antibodies to the Lyme disease spirochete.
Nadal, D, Hunziker, UA, Bucher, HU, Hitzig, WH, Duc, G. Infants born to mothers with antibodies against Borrelia burgdorferi at delivery. Eur J Pediatr 1989; 148:426–427

  • Twelve women tested positive

  • Six had a history of pre-existing Lyme disease

  • Five had unremarkable histories

  • Of these twelve women, seven had remarkable outcomes:

    • Two had elevated bilirubinemia
    • One had muscle hypotonia (laxness)
    • One was post-term, small for age, & evidenced chronic placental insufficiency
    • One had transient macrocephaly (large head)
    • One had transient supraventricular extrasystoles (“skipped heart beats”)
    • The infant born of the mother with EM had a VSD-hole in the heart connecting the two main pumping chambers.

  • None of these babies had positive blood tests for antibodies to Lyme disease

  • Conclusion was that the adverse outcomes were not due to Lyme disease

A major flaw in this research is the assumption that babies born with congenital Lyme disease are seropositive. This has been disproved by Dr. Alan MacDonald. In comparison, there is also seronegativity in babies with congenital syphilis.

In 1989, Dr. Alan MacDonald reported his findings in autopsies performed following perinatal deaths at Southampton Hospital between 1978 and 1988.
MacDonald, AB, Benach, JL, Burgdorfer, W. Stillbirth following maternal Lyme disease. NY State J Med 1987; 87:615–616

  • Routine pathology studies on tissues will not demonstrate the Lyme disease spirochete
  • Four cases where there was live birth & spirochetes were demonstrated in the placentas
  • No history or evidence of Lyme disease in the mothers, blood tests were negative in all but but one case
  • Spirochetes compatible with Borrelia burgdorferi were identified in the vital organs
  • Numerous developmental defects were observed.
  • Tissue inflammation not seen in fetuses with transplacentally acquired infection with the Lyme disease spirochete.
  • Lyme disease acquired in utero may result in fetal death in utero, fetal death at term or infant death after birth.
  • Babies may survive in spite of the bacteria being isolated in the placenta
  • In all but one case, where the Lyme disease organism was identified in the placenta or the fetal tissues, the maternal blood had no evidence of antibodies to the Lyme disease bacteria.

List of Sources

  • 1 MacDonald A. Gestational Lyme borreliosis. Implications for the fetus. Rheum Dis Clin North Am. 1989 Nov;15(4):657-77
  • 2 MacDonald AB, Benach JL, Burgdorfer W. Stillbirth following maternal Lyme disease. N Y State J Med. 1987Nov;87(11):615-6
  • 3 MacDonald A. Human fetal borreliosis, toxemia of pregnancy, and fetal death. Zentralbl Bakteriol Mikrobiol Hyg A.1986 Dec;263(1-2):189-200
  • 4 Markowitz LE, Steere AC, Benach JL, et al. Lyme disease during pregnancy. JAMA.(1986); 255(24), 3394-6
  • 5 Lavoie PE, Lattner BP, Duray PH, Barbour AG, Johnson HC. Culture positive seronegative transplacental Lyme borreliosis infant mortality. (1987) Arthritis Rheum, 30(4), 3(Suppl):S50
  • 6 Mikkelsen AL, Palle C. Lyme disease during pregnancy. (1987) Acta Obstet Gynecol Scand 66(5), 477-8
  • 7 Bale, J. F., Jr. and J. R. Murph (1992). “Congenital infections and the nervous system.” Pediatr Clin North Am 39(4): 669-90.
  • 8 Brzostek, T. (2004). “[Human granulocytic ehrlichiosis co-incident with Lyme borreliosis in pregnant woman—a case study].” Przegl Epidemiol 58(2): 289-94.
  • 9 Carlomagno G; Luksa V; Candussi G; Rizzi GM; Trevisan G Acta Eur Fertil 1988 Sep-Oct;19(5):279-81 Dept. of Obstetrics and Gynecology, University of Trieste School of Medicine. Lyme Borrelia positive serology associated with spontaneous abortion in an endemic Italian area.
  • 10 Gardner, T. (1995). Lyme disease. Infectious diseases of the fetus and newborn infant.J. S. Remington and J. 0. Klein. Philadelphia, Saunders. Chap. 11: 447-528.
  • 11 Goldenberg, R. L and C. Thompson (2003). “The infectious origins of stillbirth.” Am J Obstet Gynecol 189(3): 861-73.
  • 12 Gustafson, J. M., E. C. Burgess, et al. (1993). “Intrauterine transmission of Borrelia burgdorferi in dogs.” Am J Vet Res 54(6): 882-90. (dog study)
  • 13 Hercogova J, Vanousova D. (2008). Syphilis and borreliosis during pregnancy. Dermatol Ther. 2008 May-Jun;21(3):205-9.
  • 14 Lavoie PE;Lattner BP;Duray PH; Barbour AG; Johnson HC. Arthritis Rheum 1987; Culture positive seronegative transplacental Lyme borreliosis infant mortality. Volume 30, Number 4, 3(Suppl):S50.
  • 15 MacDonald, A. B. (1989). “Gestational Lyme borreliosis. Implications for the fetus.” Rheum Dis Clin North Am 15(4): 657-77.
  • 16 MacDonald, A. B. (1986). “Human fetal borreliosis, toxemia of pregnancy, and fetal death.”Zentralbl Bakteriol Mikrobiol Hyg [A] 263(1-2): 189-200.
  • 17 MacDonald, A. B., J. L. Benach, et al. (1987). “Stillbirth following maternal Lyme disease.” NYState J Med 87(11): 615-6.
  • 18 Maraspin, V., J. Cimperman, et al. (1999). “Erythema migrans in pregnancy.” Wien Klin Wochenschr 111(22 23): 933-40.
  • 19 Markowitz, L. E., A. C. Steere, et al. (1986). “Lyme disease during pregnancy.” Jama 255(24): 3394-6. Because the etiologic agent of Lyme disease is a spirochete, there has been concern about the effect of maternal Lyme disease on pregnancy outcome.
  • 20 Schlesinger, P. A., P. H. Duray, et al. (1985). “Maternal-fetal transmission of the Lyme disease spirochete, Borrelia burgdorferi.” Ann Intern Med 103(1): 67-8.
  • 21 Strobino BA, Abid S, Gewitz M (1999) Maternal Lyme disease and congenital heart disease: A case-control study in an endemic area. Am. J. Obstet. Gyn., 180 :711-716.
  • 22 Strobino BA, Williams CL, Abid S, Chalson R, Spierling P (1993) Lyme disease and pregnancy outcome: A prospective study of 2,000 prenatal patients. Amer J Ob Gyn, 169:367‑
  • 23 Walsh CA, Mayer EW, Baxi LV. (2007). Lyme disease in pregnancy: case report and review of the literature. Obstet Gynecol Surv. 2007 Jan;62(1):41-50.
  • 24 Williams CL, Strobino BA, Lee A, Curran A, Benach JL, Inamdar S and Cristofaro (1990) Lyme disease in childhood: Clinical and epidemiologic features of ninety cases. Pediatr. Infect. Dis., 9: 10‑
  • 25 Williams CL and Strobino BA (1990) Lyme disease and pregnancy ‑ A review of the literature. Contemporary Ob/Gyn, 35:48

A special thank you to the Lyme Disease UK organization for summarizing the pregnancy research above.