Lyme disease is an infection caused by the bacterium Borrelia burgdorferi, primarily transmitted to humans through the bite of infected blacklegged ticks. If untreated, the infection can lead to serious complications affecting the joints, heart, and nervous system. For pregnant individuals, a major concern is the possibility of the bacteria passing to the developing child, a process known as vertical transmission.
Understanding Vertical Transmission During Pregnancy
Scientific evidence indicates that Borrelia burgdorferi can cross the placenta and potentially infect the fetus while in the womb. This transplacental transmission is plausible because Lyme disease is caused by a spirochete, a type of bacteria known for its ability to penetrate tissue barriers. The presence of spirochetes has been documented in rare cases within the placenta and fetal tissues of pregnancies affected by maternal Lyme disease.
However, the frequency of confirmed vertical transmission is considered low, and most pregnancies involving a mother with Lyme disease do not result in congenital infection. Evidence supporting definite congenital Lyme disease often comes from isolated case reports rather than large-scale studies, making it difficult to determine the true overall risk. The highest theoretical risk of transmission and adverse outcomes is associated with an active, untreated maternal infection.
Research suggests that the most effective way to prevent fetal infection is through early and appropriate antibiotic treatment of the mother. Although the bacteria can be detected in fetal tissue, severe outcomes are uncommon when the mother receives prompt care.
Potential Outcomes for the Newborn
When transmission occurs, particularly in cases where the mother’s infection was untreated, it has been associated with a range of adverse pregnancy outcomes. Reported complications include miscarriage and stillbirth. Complications more often involve neonatal issues, though a consistent, defined syndrome of “congenital Lyme disease” has not been established.
Newborns exposed to untreated maternal infection may experience issues in the first weeks of life, including rashes, hypotonia, unexplained fevers, and respiratory distress. Rare reports have also described specific developmental issues, such as cardiac or neurological abnormalities, in infants born to mothers with untreated Lyme disease. These adverse outcomes are typically not seen when the mother receives timely and appropriate antibiotic treatment.
The risk of these health issues is significantly reduced when the mother’s infection is promptly managed. Studies have shown a higher risk of adverse outcomes (around 50%) in untreated cases compared to a much lower rate (approximately 11%) when the mother is treated. This difference underscores the protective role of maternal antibiotic therapy for the developing fetus.
Assessing Risk During Delivery and Breastfeeding
Concerns about the transmission of Borrelia burgdorferi during the birth process are generally considered minimal. The primary route of potential transmission is across the placenta, not during delivery. Therefore, the risk of the baby acquiring the infection while passing through the birth canal is not a major medical concern.
The risk of transmission through breast milk is also considered negligible based on current data. There are no published reports documenting the spread of Lyme disease to an infant via breast milk. Mothers undergoing antibiotic treatment for Lyme disease are generally advised that they can continue to breastfeed.
Mothers should consult with their healthcare provider to ensure the specific antibiotic prescribed is safe for use while nursing. The medical consensus supports continuing breastfeeding because the benefits of breast milk outweigh any theoretical risk of transmission.
Diagnosis and Management for Expectant Mothers
Prompt diagnosis and treatment are important for a pregnant individual who suspects they have Lyme disease. Diagnosis involves assessing the mother’s symptoms, such as the characteristic bull’s-eye rash, and using blood tests. The goal is to initiate therapy quickly to prevent the bacteria from causing complications for the mother and crossing the placenta.
Treatment protocols for pregnant individuals differ slightly from those for the general population to protect the fetus. Standard treatment typically involves an oral antibiotic such as Amoxicillin, or sometimes intravenous Ceftriaxone for disseminated cases. Doxycycline is generally avoided during pregnancy because it carries a risk of adverse effects on the baby’s bone and teeth development.
Expectant mothers can reduce their risk of infection by practicing tick bite prevention, especially when spending time in wooded or grassy areas. This involves wearing long sleeves and pants, using tick repellent, and performing thorough tick checks after being outdoors.