Protection for two: Pregnancy and sexually transmitted infections

May 17, 2025
Posted by Cornelia Grabmeier

May 17, 2025

The WHO estimates that in 2022, approximately 1.1 million pregnant women worldwide were infected with the sexually transmitted infection syphilis, leading to more than 390,000 stillbirths (WHO, 2024). In addition to stillbirths, STIs during pregnancy increase the risk of premature birth and infections in newborns. Common infections among pregnant women include chlamydia, gonorrhea, syphilis, and HIV. Regular testing and early treatment are crucial to minimize health risks for both mother and child.

This article explains how sexually transmitted infections can affect fertility and how they can be transmitted to the baby during pregnancy, potentially leading to complications. It also provides information about testing and safe treatment options and offers advice on preventive measures to best protect mother and child.

Is pregnancy possible during or after an STI?
How do STIs affect fertility, and what are the risks of untreated infections?
Can STIs be transmitted to the baby during pregnancy?
Can I breastfeed my baby if I have an STI?
What harmful effects can STI transmission have on a baby?
What are the symptoms of an STI during pregnancy?
Which STIs are tested for during pregnancy?
How are STIs treated during pregnancy, and are there safe medications?
What precautions can I take to protect my baby from STIs?
Summary

Is pregnancy possible during or after an STI?

Yes, pregnancy is possible during or despite an STI, as infections do not immediately affect fertility. However, if left untreated, STIs can cause long-term complications that may hinder conception.

How do STIs affect fertility, and what are the risks of untreated infections?

Untreated STIs can affect fertility in the long term by causing inflammation and permanent damage to the reproductive organs. The most common STIs are chlamydia and gonorrhea, which can lead to pelvic inflammatory disease (PID) and scarring of the fallopian tubes, increasing the risk of infertility and ectopic pregnancies. Other sexually transmitted diseases like Mycoplasma genitalium or HIV can also cause reproductive complications and infertility (CDC, 2024; Fertility Society of Australia, 2021).

Can STIs be transmitted to the baby during pregnancy?

Yes, certain STIs can be transmitted to the baby during pregnancy, childbirth, or breastfeeding and can lead to severe complications such as developmental disorders, malformations, or even stillbirths. Below is a table of some STIs and their transmission routes:

STI	Transmission route
HIV	Pregnancy, childbirth, breastfeeding
Syphilis	Pregnancy, childbirth (through direct contact with lesions)
Herpes	Childbirth (through direct contact with lesions)
Chlamydia, Gonorrhea	Childbirth
Hepatitis B	Childbirth, rarely breastfeeding
HPV	Childbirth (very rarely, through contact with infected tissue)

Source: Irshad, U. et al., 2023; NIH, 2019; CDC, 2024; CDC, 2020; LaCour, D. E., & Trimble, C., 2012.

Can I breastfeed my baby if I have an STI?

Whether breastfeeding is possible with an STI depends on the type of infection. Always consult your doctor to find the best solution for your individual situation.

STIs where breastfeeding is possible:
With infections like chlamydia, gonorrhea, and HPV, breastfeeding is considered safe because they are not transmitted through breast milk. Breastfeeding is also safe with hepatitis B if the baby is vaccinated immediately after birth.

STIs where breastfeeding is not recommended:
In the case of HIV, active syphilis, or herpes lesions on the breast, breastfeeding is not advised due to the potential risk of transmission. Breastfeeding is only possible if the baby does not come into contact with a lesion.

Sources: NIH, 2019; HIV.gov, 2023; CDC, 2024; CDC, 2023.

What harmful effects can STI transmission have on a baby?

The transmission of an STI to a baby can have different effects depending on the type of infection. Possible consequences include:

Low birth weight, stillbirth
Eye infection, blindness
Pneumonia
Deafness
Brain damage, meningitis
Blood infection in the baby
Acute hepatitis, chronic liver disease

Source: NIH, 2019

What are the symptoms of an STI during pregnancy?

During pregnancy, STIs can cause symptoms similar to those in non-pregnant women, such as:

Unusual-smelling vaginal discharge
Burning during urination
Lower abdominal pain
Itching or redness
Irregular bleeding

However, many infections remain asymptomatic, making regular screenings essential to protect the health of both mother and child (Mayo Clinic, 2023).

Want to get an overview of your sexual health?

During pregnancy, it’s important to actively monitor sexual health, as many sexually transmitted infections can go undetected, even in women planning a pregnancy. Regular STI testing is recommended to reduce the risk of infection and ensure the well-being of both mother and baby. Products like the Chlamydia and Gonorrhea Test, the Complete STI Test, and the STI Test Plus from Homed-IQ provide a simple way to test yourself and detect potential infections early. Early detection and treatment of STIs can not only prevent symptoms but also reduce complications during pregnancy.

Which STIs are tested for during pregnancy?

It is recommended that pregnant women are routinely screened for certain STIs to reduce risks for both mother and child. The list of recommended tests includes:

Chlamydia and gonorrhea: Routine testing, especially for young women and those at higher risk; repeat testing in the third trimester if necessary.
HIV: Testing at the beginning of pregnancy, and repeat testing in the third trimester if needed.
Syphilis: Testing at the beginning of pregnancy and repeat testing if indicated.
Hepatitis B: Testing at the beginning of pregnancy.
HPV: Pregnant women should be screened at the same intervals as non-pregnant women.

Source: CDC, 2024.

How are STIs treated during pregnancy, and are there safe medications?

Some STIs can be safely treated during pregnancy. For example, bacterial infections such as chlamydia, gonorrhea, syphilis, or trichomoniasis can be effectively treated with antibiotics that are safe for both mother and child. For incurable viral infections like herpes or HIV, antiviral medications help reduce the risk of transmission to the baby and manage symptoms. It is essential that all treatments are administered under medical supervision to ensure the safest and most effective options for both mother and child (NIH, 2019).

What precautions can I take to protect my baby from STIs?

To protect your baby from STIs and support a healthy pregnancy, the following precautions can be taken to reduce the risk of transmission:

Regular STI testing before and during pregnancy
Protected sex to prevent infection
Vaccinations, where available (e.g., for HPV or hepatitis B)
Medical consultation and early treatment of diagnosed STIs, especially if risk factors are present
Open communication with partners about sexual health and STI risks
Educating yourself about STIs to understand the risks and make informed decisions

Summary

Sexually transmitted infections pose a significant risk to both mother and child during pregnancy. They can cause stillbirth, premature birth, and developmental disorders in newborns. The most common infections in pregnant women include chlamydia, gonorrhea, syphilis, and HIV. Because many of these infections are asymptomatic and can be transmitted to the baby, regular testing and preventive measures are vital for early detection and timely treatment.

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About the author

Cornelia Grabmeier

Cornelia studied biology with a focus on neurobiology at the Ludwig Maximilian University in Munich. She currently lives in the Netherlands and is studying Management and Entrepreneurship in Health and Life Sciences at the Vrije Universiteit in Amsterdam. She is active in sports and health, enjoys traveling and has a passion for making science accessible to a wide audience and inspiring them by communicating fascinating topics.