References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
STIs during pregnancy and breastfeeding can have important consequences for both mother and baby. UK antenatal care routinely screens for the most significant infections, and effective treatments are available that are safe in pregnancy. Understanding what’s tested, what to watch for, and how breastfeeding fits in helps you make informed decisions.
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STIs Screened in Pregnancy
| Infection | Risk to Baby | Prevention |
|---|---|---|
| HIV | Mother-to-child transmission (under 1% with treatment) | ART throughout pregnancy |
| Syphilis | Congenital Syphilis, stillbirth | Penicillin treatment |
| Hepatitis B | Chronic infection in baby | Vaccine + immunoglobulin at birth |
| Chlamydia | Eye infection in newborn | Antibiotic treatment |
| Gonorrhoea | Eye infection in newborn | Antibiotic treatment |
| Herpes | Neonatal herpes (rare but serious) | Antiviral treatment; caesarean if active outbreak |
Breastfeeding Considerations
HIV
UK default is formula feeding to eliminate risk. Some clinics now support breastfeeding with undetectable viral load and close monitoring.
Hepatitis B
Breastfeeding is safe after baby receives vaccine and immunoglobulin at birth.
Other STIs
Most treated STIs don’t affect breastfeeding safety. Medications used for treatment are generally safe during breastfeeding.
Safe Treatments in Pregnancy
- Azithromycin for chlamydia (doxycycline avoided)
- Ceftriaxone for gonorrhoea
- Penicillin for syphilis
- Pregnancy-safe ART for HIV
- Aciclovir for herpes
- Metronidazole for trichomoniasis and BV
What to Do
- Accept routine antenatal screening
- Test again later in pregnancy if at ongoing risk
- Treat any infections promptly
- Ensure partners are tested and treated
Read more: STIs and pregnancy | Treatment in pregnancy | Safer breastfeeding
Frequently Asked Questions
Will STI treatment harm my baby?
Pregnancy-safe alternatives are used. Most treatments are safe.
Can I breastfeed with an STI?
Most treated STIs don’t affect breastfeeding. HIV needs specific guidance.
Should I be tested again late in pregnancy?
If you’re at ongoing risk, yes.
Related reading
- Getting Pregnant When You Have HIV
- Should I Be Tested for STIs During Pregnancy?
- STI Treatments During Pregnancy
- STIs and Pregnancy: What You Need to Know
- Safer Breastfeeding Rules for Women Living with HIV
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
