How do sexually transmitted diseases and sexually transmitted infections (STDs/STIs) affect pregnancy?

STDs/STIs pose special risks for pregnant women and their infants.

If a mother has an STD/STI, it is possible for the fetus or newborn to become infected. Some STDs/STIs, including chlamydia, gonorrhea, genital herpes, and cytomegalovirus can be passed from mother to infant during delivery when the infant passes through an infected birth canal. A few STDs/STIs, including syphilis, HIV, and CMV, can infect a fetus before birth during the pregnancy.1 It is important for a pregnant woman to be tested for STDs/STIs, including HIV/AIDS and syphilis, as a part of her prenatal care.

STD/STI testing as a part of prenatal care can determine if an expectant mother or her sexual partner has an infection that can be cured with drug treatment. Early treatment decreases the chances that the infant will contract the disease.2 While not all STDs/STIs can be cured, the mother and her health care provider can take steps to protect her and her infant.

To reduce the chance of certain STDs/STIs spreading to the infant during delivery, the health care provider might recommend a cesarean delivery.

In most hospitals, infants’ eyes are routinely treated with an antibiotic ointment shortly after birth. This is to prevent blindness due to exposure to gonorrhea or chlamydia bacteria during delivery if the pregnant woman had an undetected infection.

STDs/STIs during pregnancy can also cause2:

  • Miscarriage
  • 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
  • Birth defects, including blindness, deafness, bone deformities, and intellectual disability
  • Stillbirth
  • Illness in the newborn period (first month of life)
  • Newborn death

STDs/STIs are of special concern during pregnancy and pose significant health risks to unborn infants:

  • HIV/AIDS. HIV can be passed from mother to infant during pregnancy before birth, at the time of delivery, or after birth during breastfeeding.3
  • Gonorrhea. If a pregnant woman has a gonorrheal infection, she may give the infection to her infant as the infant passes through the birth canal during delivery. This infection in an infant can cause eye infections, pneumonia, or infections of the joints or blood. Treating gonorrhea as soon as it is detected in pregnant women will reduce the risk of transmission.2
  • Chlamydia. Similar to a gonorrheal infection, a chlamydial infection at the time of delivery can lead to eye infections or pneumonia in the infant.4 However, chlamydial infection during pregnancy also has been associated with an increased risk of preterm birth and its complications.5
  • Genital herpes. Pregnant women newly infected with genital herpes late in pregnancy have a 30% to 60% chance of infecting the infant they carry. The risk of infection is particularly high during delivery. Herpes infections in newborns are serious and potentially life-threatening. Infection with the herpes virus during pregnancy or at the time of delivery can lead to brain damage, blindness, and damage to other organs.
    • If a pregnant woman has had genital herpes in the past, there are medications that she can take to reduce the chance that she will have an outbreak and thus reduce the risk to her infant.
    • If a woman has active herpes sores when she goes into labor, the infant can be delivered by cesarean section to reduce the chance that the infant will come in contact with the virus.3
  • Hepatitis B virus. If a woman is infected with the hepatitis B virus during pregnancy, the virus also could infect her fetus. The likelihood of this occurrence depends on when the mother was infected. If the mother acquires the infection early in her pregnancy, the chance that the virus will infect her fetus is less than 10%. However, if the infection occurs later in her pregnancy, the risk goes up to 90%. Hepatitis B can be severe in infants and can threaten their lives. It also can lead to liver scarring, failure, and cancer, which can be fatal in up to 25% of cases. In addition, infected newborns have a very high risk of becoming carriers of the hepatitis B virus and can spread the infection to others.
    • In some cases, if a woman is exposed to hepatitis B during pregnancy, she may be treated with a special antibody to reduce the likelihood that she will get the infection. All healthy infants should be vaccinated against hepatitis B to give them lifelong protection against the virus.6 Infants born to women with evidence of ongoing hepatitis B infection (hepatitis B surface antigen positive) should also receive hepatitis B hyperimmune globulin as soon as possible after birth.
  • Cytomegalovirus (CMV). CMV is a common virus present in many body fluids that can be spread through close personal contact, such as kissing or sharing eating utensils, as well as sexual contact. The virus is common in the general population and usually does not cause health problems. However, if an expectant mother acquires the virus for the first time during pregnancy, the risk is high that she will pass it on to her infant. Unfortunately, a pregnant woman may not even know she has the infection, and she may still pass the virus on to her infant.7 CMV in an infant can lead to serious illness, lasting disabilities, or death.8 Each year in the United States, an estimated 40,000 infants are born with CMV infection, causing an estimated 400 deaths and leaving about 8,000 infants with permanent disabilities, such as hearing or vision loss, or intellectual disability.9 Currently routine screening for CMV in pregnancy is not recommended. Researchers are working on treatments for CMV and also vaccines to try to prevent new infections during pregnancy and to reduce the risk of transmission to the infant.


  1. March of Dimes. (2008, August). Pregnancy complications: Sexually Transmitted Infections. Retrieved June 3, 2012, from External Web Site Policy
  2. The American College of Obstetricians and Gynecologists. (2011, May). Frequently asked questions. Gynecologic problems. FAQ009. How to prevent sexually transmitted diseases. Retrieved June 2, 2012, from Patients/faq009.pdf External Web Site Policy (PDF - 191 KB)
  3. Medline Plus. (2011, September 12). Genital Herpes. Retrieved July 27, 2012, from
  4. Frommell, G. T., Rothenberg, R., Wang, S., & McIntosh, K. (1979). Chlamydial infection of mothers and their infants. The Journal of Pediatrics, 95, 28–32.
  5. Rours, G. I., Duijts, L., Moll, H. A., Arends, L. R., de Groot, R., Jaddoe, V. W., et al. (2011). Chlamydia trachomatis infection during pregnancy associated with preterm delivery: A population-based prospective cohort study. European Journal of Epidemiology, 26(6), 493–502. PMID 21538042
  6. The American College of Obstetricians and Gynecologists. (2011, August). Frequently asked questions. FAQ093. Pregnancy: Hepatitis B in Pregnancy. Retrieved June 2, 2012, from Patients/faq093.pdf External Web Site Policy (PDF - 220 KB)
  7. Lazzarotto, T., Guerra, B., Gabrielli, L., Lanari, M., & Landini, M. P. (2011). Update on the prevention, diagnosis and management of cytomegalovirus infection during pregnancy. European Society of Clinical Microbiology and Infectious Diseases, 17, 1285–1293.
  8. Eunice Kennedy Shriver National Institute of Child Health and Human Development (2007, February 23). NIH News. Experimental Vaccine Given During Pregnancy Reduces Stillbirths from Common Virus. Retrieved June 3, 2012, from
  9. Institute of Medicine (U.S.) Committee to Study Priorities for Vaccine Development. (2000). Vaccines for the 21st century: A tool for decision making. Washington D.C., National Academy Press.

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