Pregnant woman in bed smiling and wondering about the effects of an STI on her unborn fetus

How Can A Pregnant Woman’s STI Affect Her Unborn Fetus?

Written on November 30, 2023 by Jordan Stachel, M.S. RDN, CPT. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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If you are pregnant or trying to become pregnant, you may have wondered, “How can a pregnant woman’s STI affect her unborn fetus?” Read this article for everything you need to know.

What’s An STI?

STIs are sexually transmitted infections that can develop after having sex with someone who is infected. STIs are synonymous with sexually transmitted diseases (STDs), and there are several different types that can be contracted. Some of the most common types of STIs include chlamydia, genital herpes, genital warts, and hepatitis B.[1] If you or someone you know has an STI, it is important to consult a qualified healthcare provider to seek treatment.

How To Avoid Contracting An STI

Protecting yourself from contracting an STI is important. You can take steps to reduce the risk of contracting an STI [2]:

  • Asking sexual partners about their past and current status—if you choose to have sex with a partner, asking them to get tested and/or to see their latest test results before becoming intimate can reduce your risk of contracting an STI.
  • Using protection—using methods like condoms can help to reduce the risk of contracting an STI.
  • Getting vaccinated—vaccinating yourself against certain STIs like HPV can help to reduce the risk of contracting them.
  • Get tested—regular STI testing can help you get treatment, if necessary, and help prevent you from unknowingly spreading STIs to your partner.

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How Does An STI Affect Pregnant Women And Unborn Fetuses?

If you contract or have an STI while pregnant, you should be informed about potential risks for yourself and your baby.

Having an STI while pregnant increases the risk for the following [3,4]:

  • Premature labor—giving birth before 37 weeks
  • Infection—uterine infection after birth
  • Low birth weight—if you give birth to a preterm baby, there is a greater chance that they will have a low birth weight
  • Passing on the STI to the fetus during childbirth—for example, women can pass on chlamydia, which increases the baby’s risk of developing pink eye and/or pneumonia

Different STIs pose different risks to the unborn fetus. Some of the most common STIs and their potential risks include [4]:

  • Chlamydia—increased risk of preterm delivery, low birth weight, pink eye, and/or pneumonia.
  • Genital herpes—increased risk for newborn blindness, brain damage, and skin infections
  • Gonorrhea—increased risk for miscarriage, preterm birth, and chorioamnionitis (infection of the amniotic fluid).
  • Hepatitis B—increased risk for preterm birth.
  • Human immunodeficiency virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS)—an increased risk of transmitting HIV via breast milk. When women are treated with medication, the risk of passing the virus along to the fetus is very small.
  • Syphilis—increased risk for fatal infections, preterm delivery, and fetal complications within the eyes, ears, heart, skin, and bones.
  • Trichomoniasis—increased risk for preterm delivery and low birth weight.

How to Prevent Transfer Of An STI To A Fetus

The first step to preventing the transfer of an STI to your unborn baby is to know that you are infected. Because several STIs can present with no symptoms, it is important to get tested proactively before becoming pregnant, if possible.[5] Some STIs will present with symptoms including:

  • Flu-like symptoms (fever, fatigue)
  • Vaginal discharge or burning
  • Pain while going to the bathroom
  • Pain during sex
  • Eye infection
  • Sores on the mouth, vagina, genitals, or anus

If you think that you may have an STI or are wanting to rule out any possibility before becoming pregnant, you should undergo STI testing. This will help give you peace of mind and reduce the risk of any pregnancy-related complications.

If you find out that you already have an STI while pregnant, getting treated early can help to reduce the risk of any complications. If your STI is caused by bacteria, a healthcare provider will likely prescribe antibiotics to treat it. If your STI is caused by a virus, some medications may help reduce the risk of passing on the infection to the fetus but cannot treat the STI entirely.[5]

Support Your Sexual Health With Everlywell

At Everlywell, we combine the best in modernized, rigorous lab testing with easy-to-access, at-home medicine. We provide a range of blood tests and several STD tests, including testing for females, that you can take from the comfort of your home. Your results will be analyzed in CLIA-certified labs. and an experienced healthcare provider will deliver them. Take control of your sexual health today with Everlywell.

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Jordan Stachel is a Registered Dietitian Nutritionist and holds a master’s degree in Nutrition, Healthspan and Longevity from the University of Southern California. She works in private practice counseling individuals using medical nutrition therapy techniques to optimize their health outcomes. Jordan is passionate about being a dependable voice within the field of nutrition and finds great fulfillment translating complex concepts into digestible pieces of information.


  1. Sexually Transmitted Diseases: Symptoms, Diagnosis & Treatment. Cleveland Clinic. Published 2023. Accessed November 20, 2023.
  2. The Lowdown on How to Prevent STDs. Centers for Disease Control and Prevention. Published 2019. Accessed November 20, 2023.
  3. Sexually Transmitted Infections, Pregnancy, and Breastfeeding. Office of Research on Women’s Health.
  4. Pregnant? Understand the Risks of STIs. Cleveland Clinic. Published October 16, 2023. Accessed November 20, 2023.
  5. Sexually Transmitted Infections. March of Dimes. Last reviewed June 2022. Accessed November 18, 2023.
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