Bacterial Infections
Group B streptococcus
• Incidence.
In developed countries, neonatal group B streptococcus (GBS) sepsis complicates 1.8/1,000 live births.
• Maternal signs/symptoms.
Of all pregnant women, 20% are asymptomatically colonized in the vaginal or perianal region.
• Fetal/neonatal effects.
Two clinically distinct neonatal GBS infections have been identified:
1 Early-onset, neonatal GBS infection (80%) results from transmission during labor or delivery. Signs of serious infection (respiratory distress, septic shock) usually develop within 6–12 hours of birth. The mortality rate is 25% and surviving infants frequently exhibit neurologic sequelae.
2 Late-onset GBS infection (20%) is a nosocomial or community-acquired infection. It presents more than a week after birth, usually as meningitis. The mortality rate is lower than for early-onset disease, but neurologic sequelae are equally common.
• Prevention.
Strategies to prevent early-onset neonatal GBS infection vary. Patients are treated in labor if one of the following risk factors is present: a prior affected infant (not GBS positive in a prior pregnancy), GBS urinary tract infection (UTI) in index pregnancy, preterm labor, fever, or rupture of membranes ≥18 hours. This protocol results in the treatment of 15–20% of pregnant women and prevents 65–70% of early-onset GBS sepsis. US practice favors a universal screening protocol. All women are screened for GBS carrier status at 35–37 weeks. Women who are GBS carriers receive intrapartum antibiotics. The latter protocol results in the treatment of 25–30% of pregnant women and prevents 85–90% of cases of early-onset GBS sepsis. Patients with unknown GBS carrier status in labor should be treated according to the risk factor-based protocol.
Chorioamnionitis
• Incidence.
One to ten percent of pregnancies.
• Maternal signs/symptoms.
Chorioamnionitis is a clinical diagnosis. Definitive diagnosis requires a positive amniotic fluid culture. Maternal complications may include sepsis, adult respiratory distress syndrome (ARDS), pulmonary edema, and death.
• Fetal/neonatal effects.
Neonatal sepsis, pneumonia, death.
• Prevention.
Avoidance of rupture of membranes >18 hours.
Listeriosis
• Listeriosis is an uncommon cause of neonatal sepsis that may be acquired transplacentally. Cervical and blood cultures should be obtained in women with suspicious symptoms. Listeriosis is a common cause of intrauterine fetal demise and neonatal mortality rate is high.
Tuberculosis
• Incidence.
Tuberculosis (TB) in pregnant women is rare in developed countries. Cases occur most commonly among recent immigrants.
• Maternal signs/symptoms.
Most infected women are asymptomatic. Active disease at presentation is rare.
• Fetal/neonatal effects.
Congenital or neonatal TB is a highly morbid condition that may be fatal if misdiagnosed.
• Prevention.
Intradermal placement of purified protein derivative (PPD) is an accurate way to screen for TB. Interpretation of the PPD test depends on the risk status of the patient.
Bacterial vaginosis
Bacterial vaginosis (BV) is the most common cause of vaginal discharge in pregnancy. It is associated with preterm delivery in high-risk women. However, it remains unclear whether treatment for asymptomatic. BV will reduce the risk of preterm delivery.
Chlamydia infection and gonorrhea
• Incidence.
Very prevalent sexually transmitted infection.
• Maternal signs/symptoms.
Usually asymptomatic.
• Fetal/neonatal effects.
Untreated maternal chlamydia and gonorrhea infections are associated with increased neonatal morbidity.
• Prevention.
Cervical cultures in early pregnancy in high-risk women reliably detect infection. Instillation of prophylactic antibiotic ointment into the eyes of all newborns prevents eye infection.
Protozoan Infections
Toxoplasmosis
• Incidence.
Acute toxoplasmosis during pregnancy is rare.
• Maternal signs/symptoms.
Most patients are asymptomatic, but some have flu-like symptoms.
• Fetal/neonatal effects.
Only acute toxoplasmosis in pregnancy is capable of being transmitted to the fetus; 10% of infected newborns will have clinical evidence of disease.
• Prevention.
Toxoplasmosis is acquired through the ingestion of encysted organisms in raw or undercooked meat or through contact with infected cat feces. Avoid cleaning the litter box. Strict hygiene.
Trichomoniasis
• Vaginal trichomoniasis is very common.
• Treatment. Metronidazole.
Viral Infections
Rubella
• Transmission.
Airborne.
• Maternal signs/symptoms.
Rubella (“German measles”) is usually a mild viral illness.
• Diagnosis.
Serologic diagnosis requires either the presence of IgM or a significant rise in IgG antibody titer (fourfold rise over 4–6 weeks).
• Fetal/neonatal effects.
The risk of congenital rubella syndrome is 90% if maternal infection is acquired <11 weeks, 33% if 11–12 weeks, 11% if 13–14 weeks, 4% if 15–16 weeks, 0% if >16 weeks.
• Prevention.
Measles/mumps/rubella (MMR) immunization. MMR is a live vaccine and is not recommended in pregnancy.
• Management.
There is no treatment. Cytomegalovirus (CMV)
• Incidence.
One to two percent of all births.
• Transmission.
Contact with body fluids, sexual contact.
• Maternal signs/symptoms.
Of women, 20% have a non-specific viral syndrome (fever, pharyngitis, lymphadenopathy).
• Diagnosis.
The high prevalence of CMV seroreactivity (>50%) and multiple CMV serotypes limits the value of serologic screening.
• Fetal/neonatal effects.
Of infected newborns, 90% are asymptomatic at birth, but many later demonstrate deafness, learning disability, and/or delayed psychomotor development.
• Prevention.
There is no vaccine.
• Management.
There is no treatment.
Human immunodeficiency virus
• Transmission.
Sexual contact, intravenous drug use, vertical transmission.
• Maternal signs/symptoms.
Variable.
• Diagnosis.
Serum enzyme-linked immunosorbent assay (ELISA) and confirmatory western blot.
• Fetal/neonatal effects.
HIV-positive infants may develop AIDS with a high perinatal mortality rate.
• Prevention.
Safe sexual practices, avoidance of high-risk drug behavior, serial serum viral load measurements, and antiviral therapy, if indicated.
Varicella-zoster Virus
• Transmission.
Airborne (highly infectious).
• Maternal signs/symptoms.
“Chickenpox.” The maternal mortality rate approaches 50% for adults with pneumonitis or encephalitis.
• Diagnosis.
Clinical suspicion. Confirmatory serologic tests.
• Fetal/neonatal effects.
The first-trimester varicella-zoster virus (VZV) has a 2–3% risk of congenital varicella syndrome. Near-term infections resemble benign childhood infections.
• Prevention.
Only 5% of adults are not immune to VZV. Consider VZIG (varicella-zoster immune globulin) or acyclovir if a susceptible woman is exposed in pregnancy.
• Management.
Delivery should be avoided at the time of acute maternal infection. Herpes simplex virus
• Transmission.
Direct contact.
• Maternal signs/symptoms.
First-episode primary genital HSV may be associated with systemic symptoms. Both primary and recurrent HSV are characterized by painful, vesicular lesions.
• Fetal/neonatal effects.
Neonatal herpes is acquired from passage through an infected birth canal. The risk of vertical transmission is 50% for primary HSV infection and 0–4% in women with recurrent disease.
• Prevention.
Cesarean section delivery is recommended for all pregnancies complicated by primary genital HSV in labor. The management of women with a recurrent genital HSV outbreak (either lesion and/or symptoms) in labor is less clear.
Hepatitis B and C
• Incidence.
One to two percent of pregnancies.
• Transmission.
Sexual contact, intravenous drug use, vertical transmission.
• Maternal signs/symptoms.
Usually mild/moderate viral illness.
• Diagnosis
. Serologic testing.
• Fetal/neonatal effects.
Hepatitis B and C are not teratogenic, but affected infants may become carriers. Vertical transmission rates of hepatitis B range from 15% (in women who are e-antigen negative) to 80% (e-antigen positive), and of hepatitis C from 0–5% (HIV-negative women) to 35–50% (HIV-positive women).
• Prevention.
Safe sexual practices, avoidance of high-risk drug behavior. Breastfeeding is controversial, but is best avoided. Hepatitis B has an effective vaccine.
• Management.
Infants born to women with detectable hepatitis B surface antigen (HBsAg) should receive hepatitis B immunoglobulin (HBIg) and hepatitis B vaccine within 12 hours of birth. There is no effective treatment for hepatitis C. Spirochete infections
Syphilis
• Transmission.
Sexual contact.
• Maternal signs/symptoms.
Patients may exhibit primary, secondary, or tertiary syphilis.
• Diagnosis.
Serum rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) test. Confirmatory tests are required before instituting treatment.
• Fetal/neonatal effects.
Affected infants may be stillborn or exhibit signs of early or late congenital syphilis.
• Prevention.
Safe sexual practices. Congenital syphilis is unusual if the mother is treated.