Infections During Pregnancy

Most common infections that occur during pregnancy, such as those of the urinary tract or respiratory tract, cause no serious problems. However, some infections can be passed to the fetus before or during birth and harm the fetus (such as, causing deafness) or cause a miscarriage, stillbirth, or preterm birth.

Sexually transmitted infections that can cause problems include the following:

• Chlamydia may cause prelabor rupture of the membranes or preterm labor. It can also cause eye infection (conjunctivitis) in newborns.

• Gonorrhea can also cause conjunctivitis in newborns.

• Syphilis can be transmitted from a mother to the fetus through the placenta. Syphilis in the fetus can cause several birth defects, stillbirth, or problems in the newborn. Pregnant women are routinely tested for syphilis early in the pregnancy. Usually, treatment of syphilis during pregnancy cures both mother and fetus.

• Human immunodeficiency virus (HIV) infection is transmitted to the fetus in about one-fourth of pregnancies if women who have the infection are not treated. Women with HIV infection should take antiretroviral medications—this is particularly important during pregnancy. For some women with HIV infection, cesarean delivery, planned in advance, may further reduce the risk of transmitting HIV to the baby.

• Genital herpes can be transmitted to the baby during a vaginal delivery. Babies who are infected with herpes can develop a life-threatening brain infection called herpes encephalitis. A herpes infection in babies can also damage other internal organs and cause seizures, skin and mouth sores, permanent brain damage, or even death. If women have a previous history of genital herpes, they should take medications in late pregnancy to prevent active herpes at the time of delivery. In late pregnancy, if women have symptoms of herpes or develop herpes sores in the genital area late in pregnancy, the vulvovaginal area should be tested for herpes. If an active infection is confirmed, women are usually advised to give birth by cesarean delivery.

• Zika virus infection in a pregnant woman can cause the baby to have a small head (microcephaly). The head is small because it does not develop normally. Zika virus infection can also cause eye abnormalities in the baby. The Zika virus is spread by mosquitoes, but it can also be spread through sexual intercourse, through blood transfusions, and from a pregnant woman to her baby before or during birth.

Other infections that can cause problems include the following:

• Rubella can cause problems, particularly inadequate growth before birth (small for gestational age), cataracts, birth defects of the heart, hearing loss, and delayed development.

• Cytomegalovirus infection can cross the placenta and damage the fetus’s liver and brain, and the fetus may not grow as much as expected.

• Chickenpox (varicella) increases the risk of a miscarriage. It may damage the eyes of the fetus or cause defects of the limbs, blindness, or intellectual disability. The fetus’s head may be smaller than normal (microcephaly).

• Toxoplasmosis, a protozoal infection, may cause a miscarriage, death of the fetus, and serious birth defects.

• Listeriosis, a bacterial infection, increases the risk of preterm labor, miscarriage, and stillbirth. Newborns may have the infection, but symptoms may be delayed until several weeks after birth.

• Bacterial infections of the vagina (such as bacterial vaginosis) may lead to preterm labor or prelabor rupture of the membranes.

• Urinary tract infections increase the risk of preterm labor and prelabor rupture of the membranes.

Hepatitis may be transmitted sexually but is often transmitted in other ways. Thus, it is not typically considered a sexually transmitted infection. Hepatitis in a pregnant woman can increase the risk of preterm birth. It can also be transmitted from the mother to the baby during delivery, causing problems.