Many sexually transmitted infections are associated with adverse pregnancy outcomes. The Centers for Disease Control and Prevention recommends screening all pregnant women for human immunodeficiency virus infection as early as possible. Treatment with highly active antiretroviral therapy can reduce transmission to the fetus.

Chlamydia screening is recommended for all women at the onset of prenatal care, and again in the third trimester for women who are younger than 25 years or at increased risk. Azithromycin has been shown to be safe in pregnant women and is recommended as the treatment of choice for chlamydia during pregnancy. Screening for gonorrhea is recommended in early pregnancy for those who are at risk or who live in a high-prevalence area, and again in the third trimester for patients who continue to be at risk.

The recommended treatment for gonorrhea is ceftriaxone 125 mg intramuscularly or cefixime 400 mg orally. Hepatitis B surface antigen and serology for syphilis should be checked at the first prenatal visit. Benzathine penicillin G remains the treatment for syphilis. Screening for genital herpes simplex virus infection is by history and examination for lesions, with diagnosis of new cases by culture or polymerase chain reaction assay from active lesions. Routine serology is not recommended for screening.

The oral antivirals acyclovir and valacyclovir can be used in pregnancy. Suppressive therapy from 36 weeks’ gestation reduces viral shedding at the time of delivery in patients at risk of active lesions. Screening for trichomoniasis or bacterial vaginosis is not recommended for asymptomatic women because current evidence indicates that treatment does not improve pregnancy outcomes.

Infections during pregnancy affect the mother and often the child, either in utero or at the time of delivery. Many infections have been linked with increased risks of premature delivery and low birth weight, and associated morbidity and mortality. Because of these risks, the Centers for Disease Control and Prevention (CDC) has recommended screening for some sexually transmitted infections (STIs) at the first prenatal visit, then again in the third trimester for mothers at high risk. The CDC has also published recommendations for the treatment of STIs during pregnancy.

Chlamydia

C. trachomatis is the most common sexually transmitted bacterial pathogen in the United States, and as many as 5 to 15 percent of pregnant women are infected. Mother-to-child transmission of C. trachomatis can occur at the time of birth and may result in ophthalmia neonatorum or pneumonitis in the newborn, or postpartum endometritis in the mother. Some reports have linked chlamydia to low birth weight and preterm birth, but one study found no such association.

Gonorrhea

N. gonorrhea can be transmitted to the newborn from the mother’s genital tract at the time of birth and can cause ophthalmia neonatorum, systemic neonatal infection, maternal endometritis, or pelvic infection. The risk of transmission from an infected mother to her infant is between 30 and 47 percent.

Screening can be performed with a culture on Thayer-Martin media, which is recommended in a population with a low prevalence of infection. Nucleic acid hybridization tests of cervical specimens and NAATs of cervical specimens or urine are also used, with NAATs being the most sensitive and specific. Culture is the most widely available test and has the advantage of providing antimicrobial susceptibility. A repeat test is recommended in the third trimester for those at continued risk.

Hepatitis

The CDC recommends routine screening of all pregnant women for hepatitis B surface antigen (HBsAg) to detect maternal disease and avoid perinatal transmission. HBsAg is present in acute and chronic infections. The presence of immunoglobulin M antibody to hepatitis B core antigen is diagnostic of acute or recently acquired infection. HBsAg is the first detectable virologic marker for hepatitis B infection, often appearing before liver transaminases are elevated, but it may become undetectable after one to two months.

Pregnant women seeking STI treatment who have not previously been vaccinated should be vaccinated against hepatitis B. Infants of HBsAg-positive mothers should receive hepatitis B immune globulin as well as hepatitis B vaccine at birth.

Herpes Simplex Virus

Herpes simplex virus (HSV) is an extremely common STI that has potentially devastating effects on perinatally infected neonates. The risk of transmission is 30 to 50 percent higher among women who acquire genital HSV near the time of delivery. The clinical diagnosis of genital herpes during pregnancy in HIV-infected women may be a risk factor for perinatal HIV infection.

Screening is performed clinically by visualization of lesions or by patient history. Diagnosis is by culture or polymerase chain reaction assay of an active lesion. Routine serologic testing is not recommended.

Administration of acyclovir (Zovirax) or valacyclovir (Valtrex) starting at 36 weeks’ gestation has been shown to significantly reduce the recurrence of herpes simplex lesions and viral shedding at the time of delivery in patients at risk of active lesions, and to reduce the number of cesarean deliveries performed because of genital herpes. Acyclovir therapy has been shown to be cost-effective and is the CDC’s recommended treatment for HSV infection during pregnancy. The CDC also recommends using acyclovir during pregnancy for women who have recurrent genital herpes near term.

Human Immunodeficiency Virus

The U.S. Public Health Service and the U.S. Preventive Services Task Force recommend that all pregnant women in the United States be tested for HIV infection, ideally at the first prenatal visit. Testing should be voluntary and free of coercion. Women who are at high risk (e.g., those who have a history of sexually transmitted diseases, who exchange sex for money or drugs, who have multiple sex partners during pregnancy, who use illicit drugs, or who have sex partners who are HIV positive or at high risk) should be retested in the third trimester. Testing is done with an enzyme immunoassay for antibodies against HIV. Positive test results are confirmed with a Western blot or an immunofluorescence assay to rule out false-positive results.

Human Papillomavirus

Human papillomavirus (HPV) infection is extremely common and often resolves spontaneously. Testing for HPV is considered useful in triage of women with atypical squamous cells of undetermined significance on Papanicolaou smear. Treatment is not recommended in women with no cervical squamous intraepithelial lesions or genital warts.

Diagnosis of genital warts is made by visual inspection. Biopsy may be needed if the diagnosis is uncertain, if the warts do not respond to standard treatment, or if they are pigmented, ulcerated, fixed, or bleeding. Because genital warts can proliferate and become friable during pregnancy, many specialists recommend their removal. Podofilox (Condylox), imiquimod (Aldara), and podophyllin are not recommended during pregnancy. Trichloroacetic acid 80-90% applied by a health care professional weekly has been used safely in pregnancy.

BARBARA A. MAJERONI, MD, and SREELATHA UKKADAM, MBBS
State University of New York at Buffalo, Buffalo, New York

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