Can Babesiosis Pass to Your Baby During Pregnancy?

Yes, babesiosis can be passed from a mother to her baby during pregnancy, though this is considered rare ^[1][2]. This is known in medicine as congenital transmission or vertical transmission—meaning the infection moves from parent to child. If you have been diagnosed with babesiosis while pregnant, it is entirely understandable to feel anxious. However, knowing that this transmission is possible allows your medical team to carefully monitor you during pregnancy and plan for your baby’s care immediately after birth ^[3][4].

How Does Transmission Happen?

Babesiosis is caused by a microscopic parasite that infects and lives inside red blood cells. During pregnancy, this parasite can occasionally cross the placenta and infect the developing baby ^[1][2]. It is important to know that even if a pregnant person has an asymptomatic infection (carrying the parasite without feeling sick), they can still pass it to their child ^[5][4][6].

Monitoring and Treating Your Health During Pregnancy

Because babesiosis during pregnancy is uncommon, there are no universally standardized guidelines, meaning your doctors will tailor your care directly to your specific needs ^[3]. It is highly recommended to build a coordinated care team that includes an infectious disease specialist and your obstetrician/gynecologist (OB/GYN). You should also involve a pediatrician or neonatologist before delivery so they are prepared for your baby’s arrival.

Can you be treated while pregnant? Yes. Treatment for babesiosis typically involves a combination of antimicrobial or anti-parasitic medications (such as atovaquone and azithromycin). While these are standard treatments, specific data on their use during pregnancy is limited ^[7][8]. Your infectious disease specialist will carefully weigh the benefits of clearing the infection against any potential risks to your developing baby to find the safest approach.

Throughout your pregnancy, your team will monitor your blood closely to see if the infection is active. They will typically look for the parasite using two standard diagnostic techniques ^[9][10]:

• Peripheral blood smear: Looking at your blood under a microscope.
• PCR (polymerase chain reaction) test: Detecting the parasite’s DNA in your blood.

They will also closely track your baby’s development using ultrasounds to check for any signs of distress.

What Happens After Your Baby is Born?

Because transmission can occur, your baby will need to be tested for babesiosis shortly after birth, even if they seem perfectly healthy ^[4]. Testing the baby is usually done using the same blood smear and PCR tests used for adults ^[4][9].

If a baby is born with congenital babesiosis, they might show signs such as:

• Fever ^[11][5]
• Pallor (unusual paleness of the skin) ^[11][5]
• Anemia (a low red blood cell count) ^[12][6]
• Thrombocytopenia (a low blood platelet count, which can affect clotting) ^[12][6]
• Neutropenia (a low white blood cell count, making it harder to fight infections) ^[12][6]

These symptoms are non-specific and can look very similar to other common newborn infections or sepsis ^[11][5][4]. Because of this overlap, proactive testing is critical.

Important note for parents: Symptoms of congenital babesiosis in newborns do not always appear immediately on day one; they can develop weeks after delivery ^[4][5]. Even if initial tests in the hospital are clear, you should continue to watch your baby for fever, excessive sleepiness, or unusual paleness for the first several weeks at home.

If your baby needs treatment: If your baby is diagnosed with babesiosis, they will be treated immediately with antimicrobial medications designed to clear the parasite. Only in cases where the baby develops severe anemia might they require a red blood cell transfusion to stabilize their health ^[6][12]. With prompt diagnosis and proper treatment, babies generally recover fully and do very well.