Infectious Disease in Pregnancy

Common maternal infections (eg, urinary tract infection [UTIs] or respiratory tract infections) are usually uncomplicated. However, some infections increase risk for maternal or fetal morbidity or mortality. Thus, routine prenatal screening includes testing for certain infections or bacterial colonization, and pregnant patients with symptoms of infection should be evaluated and treated promptly.

Congenital anomalies or other acute or chronic disorders (eg, hearing or vision loss or neurodevelopmental issues) in a child may be caused by certain infections, including:

• Congenital syphilis

• Congenital cytomegalovirus infection

• Congenital rubella

• Congenital toxoplasmosis

• Neonatal herpes simplex virus infection

• Neonatal hepatitis B

Rates of congenital syphilis have increased significantly in the United States; from 2012 to 2021, the number of reported congenital syphilis cases per year increased 755%, from 335 to 2,865 (1). Pregnant patients should be screened for syphilis at the initial prenatal care visit. Depending on the prevalence of syphilis in their community, they should be screened 2 to 3 additional times during the pregnancy. Patients diagnosed with syphilis should be adequately treated to prevent congenital syphilis in the fetus.

HIV infectioncan be transmitted from mother to child transplacentally or perinatally. When the mother is not treated, risk of transmission at birth is about 25 to 35%. Most pregnant women in high-resource countries are treated with highly active antiretrovirals (HAART) during pregnancy, which drastically reduces the risk of mother-to-child transmission. Based on HIV viral load at 36 weeks, pregnant patients are triaged to labor and vaginal delivery versus non-laboring cesarean delivery (2).

Listeriosis is more common during pregnancy and is caused by ingestion of a large inoculum of Listeria monocytogenes in food. Listeriosis presents as gastroenteritis, usually in the third trimester, and is a common cause of hematogenous intra-amniotic infection. Listeriosis increases risk of:

• Spontaneous abortion

• Preterm labor

• Stillbirth

Listeriosis can be transmitted from mother to child transplacentally or perinatally. Treatment is with the penicillins.

Genital tract infections can cause maternal or neonatal complications, including (3):

• Bacterial vaginosis: Preterm birth, endometritis

• Chlamydia: Spontaneous abortion, preterm birth, stillbirth, neonatal conjunctivitis, and neonatal pneumonia

• Gonorrhea: Preterm birth, low birth weight, and neonatal conjunctivitis

• Prelabor rupture of the membranes

• Preterm labor

Tests for these infections are done during routine prenatal evaluations or if symptoms develop.

Genital herpes can be transmitted to the neonate during delivery. Neonatal infection may involve seizures or other serious adverse effects. Risk is high enough that cesarean delivery is preferred if the following are present (4):

• Visible herpetic lesions around the perineum, external genitals, and vagina

• Known history of infection with prodromal symptoms before labor

If visible lesions or prodrome is absent, even in women with recurrent infections, risk is low, and vaginal delivery is possible. Women with a history of genital herpes should have a pelvic examination as early as possible in labor to check for perineal, vulvar, or vaginal active lesions. Patients who are lesion-free may proceed with a vaginal delivery.

5). Pregnant women with a history of herpes should be started on an antiviral at 36 weeks gestation to prevent flares or recurrence close to delivery.