Pre-Pregnancy Infection Screen (TORCH)

The most dangerous time to catch certain common infections is during pregnancy, when a germ that would barely register in you can cross the placenta and harm a developing baby. This panel checks whether you have already met five of those infections and built lasting defenses, or whether you are still open to catching them for the first time.

It measures one specific long-term antibody (called immunoglobulin G, or IgG) against toxoplasma, rubella, cytomegalovirus (a common virus abbreviated CMV), and both types of herpes simplex virus (HSV). Read before you conceive, it tells you where you stand and, for at least one of these infections, gives you time to close the gap.

What This Panel Reveals

Your immune system keeps a written record of the infections it has fought. This panel reads one chapter of that record: the IgG antibody, which lingers in your blood for years after an infection or a vaccine. A positive result means your body has met that germ before. A negative result means you are still susceptible to catching it for the first time.

Rubella is the standout, because it is the only infection here you can act on decisively in advance. A positive result usually reflects protection from a childhood measles-mumps-rubella (MMR) shot or past infection. Catching rubella for the first time in early pregnancy is what causes birth defects, and the danger is concentrated early: widely cited estimates put the risk of congenital defects at up to about 85% when infection strikes in the first 12 weeks, falling through the second trimester and becoming rare after about week 20.

Of these five, only confirming rubella immunity is part of routine preconception care recommended by major medical groups. Screening for toxoplasma, CMV, and herpes before pregnancy is not endorsed as routine by bodies like the US Preventive Services Task Force, ACOG, or the CDC, so those results are best reviewed with a clinician who can place them in context rather than treated as standard care.

Toxoplasma and CMV tell a different story: no vaccine, but real prevention through everyday habits. A negative result on either marks you as still susceptible, which is common. In one study of over two million women planning pregnancy, only 3.20% carried toxoplasma antibodies, leaving the vast majority open to a first infection. For both germs, the chance of passing them to a baby climbs as pregnancy advances, even though the most severe fetal harm tends to follow an early infection, when transmission is actually least likely.

The two herpes simplex markers round out the picture by showing prior exposure to the cold-sore virus (type 1) and the mainly genital virus (type 2). Here a negative result is not a problem to fix but information to interpret, because the greatest newborn risk comes from catching herpes for the first time late in pregnancy, not from a long-standing infection that occasionally flares. The US Preventive Services Task Force actually recommends against routine herpes antibody screening in people without symptoms, because these blood tests can produce false positives and rarely change management, so the two herpes markers are best read with a clinician rather than acted on alone.

How to Read Your Results Together

The value of this panel is the pattern across all five markers, because immunity is usually uneven. You can be well protected against some of these infections and wide open to others, and the mix decides where your attention should go before you conceive.

One caution applies across the panel: a positive CMV or herpes result does not guarantee a baby is safe. Prior immunity lowers but does not erase the risk, because these viruses stay in the body for life and can reactivate or reinfect. Congenital CMV can still follow a repeat infection, though transmission after a first-time infection (30% to 40%) is far higher than after a non-primary one (roughly 1% to 2%).

What to Do with Your Results

If your rubella result is negative, the clearest next step is the MMR vaccine before you conceive. Because it is a live vaccine, most guidance advises waiting about a month after the shot before trying. A follow-up test can confirm you responded.

If toxoplasma or CMV is negative, prevention becomes behavioral: thorough handwashing (especially around young children's saliva and diapers), cooking meat well, washing produce, and avoiding contact with cat litter. These habits matter most once you are pregnant, when a first infection carries the risk to a baby.

For a positive result that raises questions about timing, remember that IgG cannot date an infection. If a recent infection is a concern, a clinician can add a different, short-lived antibody (immunoglobulin M, or IgM), an avidity test, or repeat testing. The herpes results are best interpreted with an obstetric clinician, since routine action on them is limited and depends on your history and your partner's.

This panel is a one-time baseline for most people. Once a marker is positive, IgG status rarely changes, so there is little reason to repeat it except to confirm a vaccine response. Pair it with an immunity check for chickenpox and screens for syphilis and hepatitis B to round out a preconception infection workup.

When Results Can Be Misleading

These are antibody snapshots, not real-time infection tests. A very recent infection may not have produced IgG yet, so a negative result taken soon after a possible exposure can be falsely reassuring. If you suspect a recent exposure, retesting later gives a truer read.

A single positive IgM (the short-lived antibody) is prone to false positives and cannot, by itself, prove a recent infection, which is why this panel relies on IgG. For the same reason, reflex antibody testing ordered only because of an unexplained ultrasound finding has a low yield and should be guided by a clinician rather than run on autopilot.