Management of STIs in pregnant patients

Overview

STI management in pregnancy requires balancing effective maternal treatment against fetal safety (medication choice) and addressing the specific risk of vertical (mother-to-child) transmission, which for several STIs (syphilis, HIV, HSV, gonorrhoea, chlamydia) carries distinct and sometimes severe consequences for the fetus/neonate if untreated
Routine antenatal STI screening is standard practice in most settings given both the prevalence of STIs in pregnancy and the substantial preventable harm of vertical transmission when identified and treated appropriately

Vertical transmission mechanisms vary by organism - transplacental (syphilis, HIV), during delivery through the birth canal (gonorrhoea, chlamydia, HSV), or a mix of routes - this timing/route distinction shapes both antenatal treatment strategy and delivery planning (e.g. caesarean section consideration for active genital HSV lesions at delivery)

Routine antenatal screening (syphilis serology, HIV, hepatitis B, and targeted STI screening based on risk factors) at first antenatal visit, with repeat screening later in pregnancy for ongoing risk given the consequences of late-pregnancy acquisition
Medication selection must account for fetal safety - e.g. doxycycline (used for chlamydia in non-pregnant patients) is avoided in pregnancy in favour of alternative agents; benzathine penicillin remains the treatment of choice for syphilis in pregnancy given no safe/effective alternative for preventing congenital syphilis

Syphilis: benzathine penicillin (penicillin desensitisation is required in confirmed allergy, given no adequate alternative for preventing congenital transmission)
HIV: antiretroviral therapy throughout pregnancy aiming for undetectable viral load by delivery, substantially reducing vertical transmission risk
Active genital HSV at term: caesarean delivery considered to reduce neonatal transmission risk
Gonorrhoea/chlamydia: pregnancy-safe antibiotic regimens, with neonatal conjunctivitis/pneumonia prevention relevant to delivery-timing infection

Congenital syphilis (penicillin desensitisation requirement in allergic patients given no alternative), vertical HIV transmission prevention (antiretroviral therapy and delivery planning), neonatal HSV (delivery mode planning for active lesions), neonatal gonococcal/chlamydial conjunctivitis
Penicillin remains the only effective treatment for preventing congenital syphilis, meaning a pregnant patient with a penicillin allergy history and confirmed syphilis requires penicillin desensitisation rather than substitution with an alternative antibiotic class - this is a frequently tested exception to the general principle of avoiding a drug in a documented allergic patient

4 more sections, plus exam facts

Premium unlocks every note across every specialty, and the full exam fact library behind it.