What this test measures
TORCH is a historical acronym for a group of infections that can pass from mother to baby during pregnancy and cause significant foetal harm: Toxoplasmosis, Other (syphilis, parvovirus, varicella, HIV, Zika, etc.), Rubella, Cytomegalovirus, and Herpes simplex. The TORCH 8 panel measures IgG (long-term immunity) and IgM (recent infection) antibodies against the four core pathogens: Toxoplasma gondii, Rubella, CMV, and HSV 1/2 — giving 8 results in total.
IgG-positive / IgM-negative usually means past infection or vaccination — and importantly, immunity to re-infection during this pregnancy. IgM-positive (with or without IgG) raises suspicion of recent or active infection and triggers confirmatory testing (avidity index, PCR, repeat serology, sometimes amniocentesis) before any treatment decision is made.
Why it matters
The TORCH panel is routinely ordered in two situations in Indian practice: (1) at the antenatal booking visit if the mother does not have documented immunity, and (2) when an ultrasound shows foetal abnormalities (IUGR, hydrocephalus, intracranial calcification, hepatosplenomegaly) that raise suspicion of congenital infection. Each of these infections has specific consequences — Rubella in early pregnancy can cause congenital rubella syndrome (deafness, cataract, heart defects); CMV is the leading non-genetic cause of congenital sensorineural deafness; primary toxoplasmosis can cause chorioretinitis and brain damage; neonatal herpes can be devastating if undiagnosed at delivery.
IMPORTANT: TORCH testing is over-ordered and over-interpreted in India. A positive IgM is not by itself proof of recent infection — false positives are common, and immunity from past infection or vaccination (positive IgG) means the baby is generally protected. Always interpret with an obstetrician familiar with avidity testing and PCR confirmation.
How to prepare
No fasting required. Disclose any recent fever, rash, exposure to pets (cats — toxoplasmosis), unpasteurised foods, or contact with children with viral illness. Bring vaccination history (rubella / MMR especially).
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Toxoplasma IgG[1] | Negative (non-immune) or Positive (immune) | Negative IgG = no past exposure, no immunity. Avoid raw/undercooked meat, raw vegetables not properly washed, cat litter boxes through pregnancy. | Positive IgG with negative IgM = past infection, immune, baby protected. |
| Toxoplasma IgM | Negative | — | Possible recent infection. Confirm with IgG avidity test (high avidity = old infection, low avidity = recent). Consider amniocentesis for foetal infection if confirmed. |
| Rubella IgG[1] | Positive (immune) | Non-immune — avoid contact with rash illnesses; receive MMR post-partum. | Positive — immune; baby protected. |
| Rubella IgM | Negative | — | Possible primary rubella — high risk to baby in first trimester (congenital rubella syndrome). Confirm with avidity / PCR. False positives are common. |
| CMV IgG[1] | Negative or positive (~80% Indian women positive) | Non-immune — practise hand hygiene around young children (CMV is transmitted via saliva and urine of toddlers). | Past infection; some risk of reactivation in pregnancy but lower foetal risk than primary infection. |
| CMV IgM | Negative | — | Possible primary CMV — highest-risk infection of the panel for the foetus. Confirm with avidity and consider amniocentesis with PCR if positive in early pregnancy. |
| HSV 1/2 IgG | Negative or positive | Non-immune to HSV. Avoid contact with active oral or genital lesions. | Past infection. Recurrence risk during pregnancy — disclose any active lesions before delivery for caesarean planning. |
| HSV 1/2 IgM | Negative | — | Possible primary HSV infection. Primary genital HSV near delivery is the major risk for neonatal herpes; antiviral therapy + caesarean often recommended. |
Reading a TORCH panel result
| IgG | IgM | Interpretation |
|---|---|---|
| Negative | Negative | Susceptible — no immunity, no current infection. Counsel on prevention. |
| Positive | Negative | Past infection / vaccination — immune, baby protected. |
| Positive | Positive | Recent infection, late primary, or reactivation. Confirm with avidity and PCR. |
| Negative | Positive | Possible very recent primary infection or false positive. Confirm with repeat in 2–3 weeks + avidity. |
Frequently asked questions
Why is the TORCH 8 panel done?
To identify pregnant women who are non-immune to common congenital infections, and to investigate suspected congenital infection when ultrasound abnormalities (IUGR, brain calcification, hepatosplenomegaly) are seen.
When is the best time to do it?
Ideally pre-conception or at the booking visit (6–12 weeks). Doing it for the first time after 20 weeks gives less actionable information because most chromosomal/structural decisions have already been made.
My IgM is positive — does that mean my baby is at risk?
Not necessarily. IgM positives are frequently false (especially Rubella IgM and Toxoplasma IgM). The next step is an avidity test (high avidity = old infection; low avidity = recent), repeat serology, and sometimes PCR on amniotic fluid. Do not start treatment on IgM alone.
Do I need to fast?
No.
I am Rubella IgG negative — can I get the vaccine now?
No — MMR is a live vaccine and must not be given during pregnancy. You will receive it after delivery before discharge. During this pregnancy, avoid anyone with rash illness.
What does positive CMV IgG mean for my baby?
A positive IgG with negative IgM means past infection. Some risk of reactivation exists but the risk of severe foetal CMV is much lower than with a primary infection in pregnancy. Around 80% of Indian women have positive CMV IgG by adulthood.
Should every pregnant woman do TORCH testing?
Routine TORCH screening is controversial — it is over-ordered in India and many positive IgM results are false. It is most useful when (a) there are ultrasound abnormalities, (b) the mother has had high-risk exposure, or (c) the pregnancy is from IVF where the booking visit is delayed.
What is TORCH 10?
A variant panel that adds two more pathogens (typically Parvovirus B19, Varicella zoster, or HIV) for a total of 10 measurements. Choose 10 if you have a specific concern or known exposure.
Related Pregnancy / Prenatal tests
Tests commonly ordered alongside TORCH 8, or that help interpret an unexpected result.
Sources & references
- CDC — Cytomegalovirus and Pregnancy · accessed 2026-05-30T00:00:00.000Z
- CDC — Rubella in Pregnancy · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Toxoplasmosis · accessed 2026-05-30T00:00:00.000Z
- ACOG — Practice Bulletin on Toxoplasmosis and Cytomegalovirus · accessed 2026-05-30T00:00:00.000Z
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