# Rubella and Congenital Rubella Syndrome

> Rubella and congenital rubella syndrome for NEET-PG Obstetrics and Gynaecology, covering gestation risk, the defect triad and postpartum vaccination.

- Canonical URL: https://prepelephant.com/topics/neet-pg/obstetrics-and-gynaecology/rubella-and-congenital-rubella-syndrome
- Exam / course: NEET-PG · Subject: Obstetrics and Gynaecology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-08
- Last updated: 2026-10-08
- Reference basis: Williams Obstetrics; Park's Textbook of Preventive and Social Medicine; Ananthanarayan and Paniker's Textbook of Microbiology
- How to cite: "Rubella and Congenital Rubella Syndrome", PrepElephant, https://prepelephant.com/topics/neet-pg/obstetrics-and-gynaecology/rubella-and-congenital-rubella-syndrome

## Direct answer

Rubella and congenital rubella syndrome describe maternal rubella infection and the fetal defects that can follow it, with risk depending strongly on gestational age at infection. Infection in the first trimester carries the highest risk of defects, and the classic triad is cataract, sensorineural deafness and patent ductus arteriosus. Non-immune women are offered measles-rubella vaccination after delivery, because live vaccine is contraindicated in pregnancy.

## What you must remember

- **Risk by gestation:** Highest when infection occurs in the first trimester and falling as pregnancy advances; defects after about 20 weeks are uncommon.
- **Classic triad:** Cataract, sensorineural deafness and patent ductus arteriosus; pulmonary artery stenosis is also described.
- **Other features:** Intrauterine growth restriction, microcephaly, meningoencephalitis, thrombocytopenia, hepatosplenomegaly and blueberry muffin rash.
- **Late sequelae:** Progressive panencephalitis, late-onset hearing loss, diabetes and thyroid disease can appear years after birth.
- **Booking test:** Rubella IgG at booking shows whether the woman is immune; a non-immune result leads to counselling and a postpartum vaccination plan.
- **Vaccination:** Measles-rubella vaccine after delivery for non-immune women, because it is a live vaccine avoided in pregnancy.
- **Post-vaccine precaution:** Avoid pregnancy for about one month after vaccination; breastfeeding is not a contraindication.

## Immunity, exposure and gestation: a stepwise approach

A pregnant woman with suspected rubella exposure is assessed by immune status and by the gestation at exposure, because both decide the counselling. The steps below follow that order.

1. **Check immunity:** Rubella IgG on the booking sample shows whether the woman is immune, and a non-immune result starts counselling and vaccination planning.
2. **Confirm recent infection:** Rubella IgM with a rising IgG titre on paired samples confirms infection; IgM can be falsely positive, so a reference laboratory result is preferred.
3. **Date the exposure:** Work out the gestational age at infection, because the defect risk depends on it and shapes the counselling.
4. **Scan the fetus:** Serial ultrasound looks for growth restriction and structural defects; fetal echocardiography is used when a cardiac anomaly is suspected.
5. **Counsel on outcome:** Explain the gestation-specific risk and the legal options under the Medical Termination of Pregnancy Act, in a balanced discussion.
6. **Vaccinate after delivery:** Give measles-rubella vaccine postpartum to non-immune women, and advise contraception for about one month afterwards.

## Where the examiner tries to catch you

Rubella questions test the gestation-risk relationship, the triad and the postpartum vaccine timing.

- **Trap:** Vaccinating a non-immune pregnant woman with MR vaccine — **Correct:** Live vaccine is avoided in pregnancy, so vaccination waits until after delivery.
- **Trap:** Assuming infection after 20 weeks always causes defects — **Correct:** Risk of defects falls sharply with later gestation, although late sequelae such as deafness can still occur.
- **Trap:** Stopping breastfeeding after MR vaccination — **Correct:** Breastfeeding is not a contraindication to rubella or MR vaccination.

## Frequently asked questions

### Which gestational period carries the highest risk of congenital rubella defects?

Infection during the first trimester carries the highest risk of congenital rubella defects, and the risk falls as gestation advances. Infection after about 20 weeks rarely causes defects, although late complications can still occur.

### What is the classic triad of congenital rubella syndrome?

The classic triad of congenital rubella syndrome is cataract, sensorineural deafness and patent ductus arteriosus. Congenital glaucoma, pigmentary retinopathy and intellectual disability are also described as features of the syndrome.

### Why is MR vaccine given after delivery and not during pregnancy?

Measles-rubella vaccine is a live attenuated vaccine, so it is avoided during pregnancy. Non-immune women are vaccinated after delivery, and contraception is advised for about one month afterwards.

### Is breastfeeding allowed after postpartum rubella vaccination?

Breastfeeding is allowed after rubella or MR vaccination, because it is not a contraindication. Standard guidance does not regard the vaccine virus as a risk to a breastfed infant.