STI Screening During Pregnancy: Tests, Risks and the Right Time

Pregnancy makes health checks twice as important, but screening for sexually transmitted infections often receives less attention. That is especially risky because several common infections can be present without symptoms, including in pregnant women.

An undetected infection can continue developing and reach the fetus through the placenta, during childbirth or through breastfeeding. Early screening gives doctors time to treat the infection before it progresses or affects the pregnancy.

The recommended tests include HIV, syphilis and hepatitis B. Pregnant women with undetected HIV who do not receive antiretroviral therapy face a high risk of transmitting the virus to their babies, while early testing and appropriate treatment can reduce that risk to a very low level. HIV testing is recommended at the first antenatal visit.

Untreated syphilis can cause miscarriage, stillbirth, premature birth or congenital syphilis, which can damage a baby’s brain, bones and internal organs. Penicillin treatment can stop transmission. Babies born to mothers with active hepatitis B should receive hepatitis B immunoglobulin and a hepatitis B vaccine within the first 12 hours after birth.

Chlamydia and gonorrhea are also often symptomless. They can increase the risk of premature birth and cause newborn conjunctivitis, with untreated gonorrhea potentially leading to blindness. Screening usually uses blood samples for HIV, syphilis and hepatitis B, and cervical swabs or urine samples for chlamydia and gonorrhea. The procedures are brief and generally not painful. Repeat HIV and syphilis screening in the third trimester may be advised for women in high-prevalence areas or with specific risk factors.