What are the risks and management options for a pregnant woman with congenital rubella syndrome?

Congenital Rubella Syndrome: Clinical Features and Prevention

Clinical Manifestations

Congenital rubella syndrome results from maternal rubella infection during pregnancy and causes a constellation of severe, permanent birth defects that profoundly impact morbidity, mortality, and quality of life. 1

Classic Triad of Defects

The most common anomalies include:

• Auditory defects: Sensorineural deafness is the most common manifestation of CRS 2
• Cardiac defects: Patent ductus arteriosus, peripheral pulmonary artery stenosis, atrial or ventricular septal defects 1
• Ophthalmic defects: Cataracts, microphthalmia, glaucoma, chorioretinitis 1

Additional Manifestations

• Neurologic complications: Microcephaly, meningoencephalitis, mental retardation 1
• Growth abnormalities: Both intrauterine and postnatal growth retardation occur frequently 1
• Other findings: Radiolucent bone defects, hepatosplenomegaly, thrombocytopenia, purpuric skin lesions 1
• Delayed manifestations: Diabetes mellitus, thyroid disease, and glaucoma can develop years after birth, necessitating long-term follow-up 3

Gestational Age-Specific Risks

The risk of fetal defects is critically dependent on the timing of maternal infection, with the highest risk occurring in the first trimester. 2

First Trimester (Highest Risk)

• 85% of infants are affected when maternal infection occurs during the first 8 weeks of gestation 1
• Risk decreases to approximately 52% for infections occurring during weeks 9-12 1

Second Trimester

• Risk declines to 10-24% when infection occurs between 13-16 weeks 2
• Infection after the 20th week of gestation rarely causes defects 1

Important Caveat

• Even subclinical (inapparent) maternal rubella infection can cause congenital malformations 1
• Fetal infection without clinical signs of CRS can occur during any stage of pregnancy 1

Recognition and Diagnosis

At Birth

• Infants who are moderately or severely affected by CRS are readily recognizable at birth 1
• Mild CRS (slight cardiac involvement or deafness) may be detected months or years after birth, or not at all 1

Prenatal Diagnosis

• Detection of rubella-specific IgM antibodies in fetal blood is helpful in establishing the diagnosis prenatally and can aid in pregnancy management 3

Management of Pregnant Women with Rubella Exposure

If Seronegative (No IgG Immunity)

Immune globulin (IG) is NOT recommended for post-exposure prophylaxis because it will not prevent infection or viremia, and may only modify or suppress symptoms, creating a false sense of security. 2

• IG has not been proven effective in preventing congenital rubella syndrome 2
• Monitor closely for development of rubella symptoms (rash, fever, lymphadenopathy) 2
• If symptoms develop, obtain serum for rubella-specific IgM antibody testing, ideally between 1-2 weeks after rash onset 2
• Consider paired sera testing with acute-phase serum collected as soon as possible after symptom onset, and convalescent-phase serum collected 10 or more days later 2

If Seropositive (IgG Positive)

• The presence of IgG antibodies indicates past infection and established immunity, providing protection against primary infection during pregnancy 4
• With IgG-positive and presumed IgM-negative results, there is no increased risk of CRS in the current pregnancy 4
• No additional serologic testing is needed unless clinical suspicion for acute infection develops 4
• No rubella vaccination is needed postpartum, as documented IgG immunity indicates protection 4

Prevention Strategy

Postpartum Vaccination (Critical for Seronegative Women)

Women who remain rubella-seronegative postpartum should receive immediate MMR vaccination before hospital discharge to prevent congenital rubella syndrome in future pregnancies. 2

• Approximately 10-20% of women of childbearing age remain susceptible to rubella despite childhood vaccination programs 2, 3
• Counsel the patient to avoid pregnancy for 3 months following vaccination 2
• Without vaccination, seronegative mothers remain at risk for rubella infection during any future pregnancy, with devastating consequences including miscarriage, stillbirth, and severe fetal anomalies 2

Important Reassurance

• Although live, attenuated rubella vaccine is contraindicated during pregnancy, pregnant women who are inadvertently immunized are not candidates for pregnancy termination because no defects consistent with congenital rubella have been reported in the offspring of similarly vaccinated women 3

Counseling Considerations

When Maternal Infection is Confirmed

Pregnancy termination should not be routinely recommended based solely on confirmed maternal infection—adequate prenatal counseling and diagnostic workup are mandatory. 2

• Explicit counseling about the 85% risk of fetal defects in first-trimester infection is essential 2
• Women who develop a rubella-like illness during pregnancy should have the diagnosis confirmed serologically because a diagnosis based on clinical criteria alone is unreliable, given that 25%-50% of rubella infections are subclinical and clinically similar illnesses are caused by parvovirus, adenoviruses, and enteroviruses 1

Maternal Complications

• Joint symptoms (arthralgia/arthritis) occur in up to 70% of infected adult women and typically resolve spontaneously, though they may persist for 1 day to 3 weeks 2
• Thrombocytopenia occurs at a ratio of 1 per 3,000 cases and is more likely to affect children 1
• Encephalitis occurs at a ratio of 1 per 6,000 cases and is more likely to affect adults 1

Global Context

• In the last major U.S. rubella epidemic during 1964-1965, an estimated 20,000 cases of CRS occurred 1
• While rubella elimination has been verified in 98 (51%) of 194 WHO countries by 2022, imported CRS remains a public health concern in the United States, particularly from regions where rubella remains endemic 5, 6