Congenital & Perinatal Infections

Causes & Risk Factors

Congenital and perinatal infections can be transmitted from mother to baby through several routes:

•  Transplacental transmission during pregnancy — relevant to infections such as CMV, toxoplasmosis, rubella, and syphilis.

•  Transmission during delivery — relevant to infections such as hepatitis B, HIV, and certain other pathogens present in maternal blood or genital secretions.

•  New or first-time maternal infection during pregnancy generally carries higher transmission risk to the fetus than infection acquired before pregnancy, for several of these organisms.

•  Lack of routine antenatal screening, which may leave a maternal infection undetected and untreated during pregnancy.

Symptoms & When to Test

Maternal infection is often asymptomatic, while newborn signs vary depending on the specific infection and timing of transmission.

•  Maternal infection is frequently asymptomatic or causes only mild, nonspecific symptoms, which is why screening (rather than symptom-based testing alone) is important during pregnancy

•  Newborn signs may include growth restriction, jaundice, skin rash, hearing or vision problems, or other findings identified at or after birth

•  Some congenital infections may not become apparent until later in infancy or childhood

When Should You Consider Testing?

Maternal screening is generally recommended as part of routine antenatal care, according to established protocols. Additional or repeat testing may be considered with specific risk factors, known exposure during pregnancy, or abnormal findings on prenatal ultrasound.

Why Tests Are Combined

Several congenital infections are often screened together (sometimes referred to informally as a "TORCH"-type panel) because their consequences for the fetus can overlap in presentation, and identifying maternal infection status for several organisms at once is often more efficient during routine antenatal screening than testing sequentially based on symptoms that may never appear.

Interpreting maternal antibody results (IgG vs. IgM, and timing relative to pregnancy) requires care, since the presence of IgG may reflect immunity from a past infection (generally reassuring) rather than a new, active infection during the current pregnancy (which carries different implications) — this distinction is central to correct interpretation and is best made by a specialist.

When a newborn is suspected to have a congenital infection, testing the newborn directly (rather than relying only on maternal results) may be needed to confirm active infection, since maternal antibodies can cross the placenta and be present in a newborn's blood without indicating actual newborn infection.

Tests Available at NPL

Most infectious-disease molecular tests and microbiological investigations do not require fasting. However, some blood tests ordered at the same time may have specific preparation requirements. Please follow the instructions provided by your doctor or NPL.

Home Sample Collection

Maternal blood testing for congenital infection screening can typically be arranged through NPL's standard home sample collection service.

Newborn testing for suspected congenital or perinatal infection is generally performed in a hospital or neonatal care setting by specialist staff, given the clinical urgency and specific handling requirements — this is not a home collection service.

Reports are delivered securely to your treating obstetrician or pediatrician, and to you, within the timeframe specified for the tests ordered.

When to See a Doctor

•  As part of routine antenatal care — discuss recommended screening with your obstetrician

•  Known exposure to an infection (such as rubella or toxoplasmosis) during pregnancy

•  Abnormal findings on prenatal ultrasound suggestive of possible infection

•  A newborn with signs suggestive of congenital infection — evaluated promptly by a pediatrician