Why are sexually transmitted diseases (STDs) and sexually transmitted infections (STIs) of particular concern for pregnant women?

Some infections—such as Zika, gonorrhea, chlamydia, HIV, and syphilis—can pass to the fetus during pregnancy or to the infant during delivery, causing short- and long-term health problems. However, the risk of transmission can be lowered or even eliminated with appropriate treatments.

For this reason, it is important for a pregnant woman to be tested for STDs/STIs as a part of her prenatal care. Prenatal STI testing can determine whether a pregnant woman has an infection that can be cured or controlled with drug treatment, which decreases the chances that the infant will contract the disease.1 The pregnant woman and her health care provider can take other steps to protect her health and her infant's health if the STI is one that cannot be cured or treated.

Some examples of ways to reduce or eliminate risk of transmission include the following:

  • HIV can be passed from mother to infant during pregnancy before birth, at the time of delivery, or after birth during breastfeeding.2 Treatment during pregnancy near delivery prevents this transmission.
  • Recent research also shows that, for HIV-infected mothers whose immune system is in good health, treatment during breastfeeding virtually eliminates transmission of HIV through breastmilk.3 Women who have HIV but whose immune systems are not in good health should not breastfeed their infants if safe alternatives, such as infant formula, are available.1
  • If a woman has active herpes lesions, untreated HIV, or an HIV viral load that is not suppressed, the infant can be delivered by cesarean section (also referred to as C section) to prevent transmission of the infection.
  • For infections, such as gonorrhea, a pregnant woman and her sexual partner can be treated before the birth, and the infant can be treated at birth to prevent infection.1
  • In most hospitals, infants' eyes are routinely treated with an antibiotic ointment shortly after birth. The ointment can prevent blindness from exposure to gonorrhea or chlamydia bacteria during delivery, in case the pregnant woman had an undetected infection.
  • Women who are pregnant or are thinking about getting pregnant are advised not to travel to areas where Zika infection has been reported. Preventing mosquito bites can also reduce the risk for infection and transmission.

STIs during pregnancy can also cause:2

  • Miscarriage (fetal loss before 20 weeks)
  • Ectopic pregnancy (when the embryo implants outside of the uterus, usually in a fallopian tube)
  • Preterm labor and delivery (before 37 completed weeks of pregnancy)
  • Low birth weight
  • Congenital anomalies, including blindness, microcephaly, deafness, bone deformities, and intellectual disability
  • Stillbirth (fetal loss at or after 20 weeks)
  • Illness in the newborn period (first month of life)
  • Newborn death
  • Health complications in the mother

Visit the What infections can affect pregnancy? section of this website for more information.


  1. Medline Plus. (2014). Genital herpes. Retrieved January 4, 2016, from http://www.nlm.nih.gov/medlineplus/ency/article/000857.htm
  2. American College of Obstetricians and Gynecologists. (2011). Frequently asked questions: HIV and pregnancy. Retrieved June 27, 2012, from http://www.acog.org/~/media/For%20Patients/faq113.pdf?dmc=1&ts=20120711T1503446877  (PDF 328 KB)
  3. NIH. (2016). HIV therapy for breastfeeding mothers can virtually eliminate transmission to babies. Retrieved November 29, 2016, from https://www.nih.gov/news-events/news-releases/hiv-therapy-breastfeeding-mothers-can-virtually-eliminate-transmission-babies
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