Infections During Pregnancy

Most common infections that occur during pregnancy, such as those of the skin, urinary tract, and respiratory tract, cause no serious problems. However, some infections can be passed to the fetus before or during birth and damage the fetus or cause a miscarriage or premature birth. Also, whether taking antibiotics and other antimicrobial drugs is safe during pregnancy is a concern.

Sexually transmitted infections that can cause problems include the following:

• Chlamydial infection may cause preterm labor and premature rupture of the membranes. It can also cause eye inflammation (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 and cause 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 to one third of pregnancies if women who have the infection are not treated. Experts recommend that women with HIV infection take antiretroviral drugs during pregnancy. If women take a combination of antiretroviral drugs, the risk of transmitting HIV to the fetus can be reduced to as low as 1%. For some women with HIV infection, cesarean delivery, planned in advance, may further reduce the risk of transmitting HIV to the baby. Pregnancy does not seem to speed up the progression of HIV infection in women.

• 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 skin and mouth sores, permanent brain damage, or even death. If women develop herpes sores in the genital area late in pregnancy or if herpes first develops during late pregnancy, women are usually advised to give birth by cesarean delivery, so that the virus is not transmitted to the baby. If no sores are present and herpes develops earlier, the risk of transmission is very low, and vaginal delivery is possible.

• 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.

Infections that are not transmitted sexually and that can cause problems include the following:

• German measles (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 premature rupture of the membranes containing the fetus.

• Urinary tract infections increase the risk of preterm labor and premature rupture of the membranes containing the fetus.

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 premature birth. It can also be transmitted from the mother to the baby during delivery, causing problems.