01Purpose and principlesWhat the treatment does and how it fits into care.
Vertical transmission can occur in utero, around delivery or during breast or chestfeeding. Modern ART and coordinated perinatal care make transmission uncommon in the UK, but the remaining risk concentrates around untreated infection, seroconversion, viraemia, incomplete adherence, late diagnosis and unplanned feeding exposure. The goal is sustained maternal health and viral suppression, not a single obstetric procedure.
Planning begins before conception where possible and is revisited at booking, after treatment changes, near term, at labour and after birth. HIV RNA has to be interpreted with timing and trajectory. A value below 50 copies/mL supports vaginal birth; detectable viraemia changes delivery and infant prophylaxis. Obstetric indications remain valid, and a person with HIV should not be denied standard maternity care.
Infant feeding counselling distinguishes elimination of breast-milk exposure by formula from the small residual risk during supported feeding despite maternal suppression. Choice requires accessible formula where selected, adherence support, prompt management of mastitis or infant oral disease, and an agreed testing schedule. Stigma, disclosure and safeguarding needs are addressed without coercion.
Key points
- Offer and document antenatal HIV screening; confirm a reactive result urgently and involve specialist HIV, obstetric and paediatric teams without waiting for symptoms.
- Continue effective antiretroviral therapy in pregnancy; check adherence, interactions, tolerability, resistance history and HIV RNA because durable viral suppression is the central preventive intervention.
- BHIVA 2025 birth thresholds are explicit: support planned vaginal birth when HIV RNA is below 50 copies/mL; recommend planned caesarean at 50–399 after considering trajectory, treatment duration, adherence, obstetric factors and patient preference; recommend caesarean at 400 copies/mL or above.
- If labour starts with HIV RNA 50–399 copies/mL at term, BHIVA recommends immediate caesarean; if birth is already advanced, expedite safely with senior HIV and obstetric advice.
- Formula feeding removes postnatal breast-milk exposure. Sustained suppression can support an informed breast or chestfeeding choice, but risk is not zero and enhanced maternal and infant monitoring is required.
- Neonatal antiretroviral prophylaxis and virological testing are risk-stratified from maternal viral load, treatment history, timing of diagnosis, adherence, birth events and feeding plan; give the first dose promptly after birth.
- Avoid unnecessary invasive fetal monitoring and procedures when alternatives are clinically suitable, while never delaying essential obstetric intervention for maternal or fetal safety.
02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.
A repeatedly reactive screening pathway requires confirmatory laboratory testing and urgent linkage, including baseline HIV RNA, CD4 count, resistance and hepatitis assessment.
Detectable HIV RNA near birth may reflect recent treatment, missed doses, interaction, vomiting, malabsorption or resistance and changes delivery and neonatal planning.
Fever, rash, lymphadenopathy or a new high-risk exposure with a negative or indeterminate assay can represent acute HIV and requires HIV RNA assessment.
Labour, ruptured membranes, bleeding or threatened preterm birth requires the current obstetric emergency pathway plus HIV-specific planning.
Mastitis, cracked bleeding nipples, infant oral lesions or maternal viraemia during breast or chestfeeding prompts immediate specialist advice and temporary feeding decisions.
03Assessment before treatmentTests and checks that guide safe selection.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Confirmed HIV diagnostic algorithmFirst step - Why
- Distinguish a reactive screen from confirmed HIV and identify HIV type where relevant.
- Interpretation and limitations
- A negative earlier test does not exclude later pregnancy acquisition; repeat testing or HIV RNA is needed after a recent exposure or seroconversion syndrome.
- 02
Quantitative plasma HIV RNA - Why
- Measure treatment response and provide the near-term value used for delivery and infant-risk decisions.
- Interpretation and limitations
- Use the actual result, timing and trajectory; below 50, 50–399 and at least 400 copies/mL lead to distinct BHIVA delivery recommendations.
- 03
Resistance and treatment review - Why
- Identify transmitted or selected resistance and prevent ineffective regimen changes.
- Interpretation and limitations
- Do not wait for resistance results to begin an expert-chosen active regimen when treatment is urgent; revise once results and history are available.
- 04
CD4 count and coinfection screen - Why
- Assess immune status and detect hepatitis, syphilis and other infections affecting maternal or neonatal care.
- Interpretation and limitations
- CD4 count guides opportunistic-infection considerations but does not replace HIV RNA for delivery planning.
- 05
Infant HIV nucleic-acid testing - Why
- Detect vertically acquired infection because maternal antibody makes routine antibody testing unsuitable early in infancy.
- Interpretation and limitations
- Test timing and duration depend on prophylaxis and feeding exposure; breast or chestfeeding requires testing through and after the exposure period.
04Treatment approachPreparation, options, escalation and aftercare.
01New diagnosis pathwayLink treatment and maternity care immediatelyFirst stepAn antenatal HIV screen is reactive or acute infection is suspected during pregnancy.+
- 1ConfirmatoryExplain the result carefully, send confirmatory testing and baseline HIV RNA, CD4, resistance and coinfection samples, and contact the specialist team the same day.
- 2Start or optimise pregnancy-appropriate ART promptly with interaction, renal, hepatic, resistance and adherence review; do not wait for symptoms.
- 3Agree repeat viral-load timing, disclosure support, partner testing and a provisional birth, infant-prophylaxis and feeding plan that is updated as results change.
02Birth planning pathwayUse viral load and obstetric contextA current HIV RNA result is available near term or labour begins before the plan is complete.+
- 1Below 50 copies/mL support planned vaginal birth unless an obstetric indication favours caesarean.
- 2At 50–399 copies/mL recommend planned caesarean after weighing trajectory, treatment duration, adherence, obstetric factors and informed preference; immediate caesarean is recommended if labour begins at term.
- 3At 400 copies/mL or above recommend caesarean, obtain urgent specialist advice on intrapartum ART and minimise avoidable invasive procedures without withholding essential care.
03Postnatal pathwayProtect the infant and sustain maternal careBirth has occurred to a person living with HIV.+
- 1Give neonatal prophylaxis promptly using the specialist risk category and document exact medicine, dose, duration and who will supply it.
- 2Implement formula support or the enhanced breast or chestfeeding plan, including action for viraemia, breast inflammation, infant oral disease or adherence interruption.
- 3Complete infant virological testing, maternal ART follow-up, contraception discussion, mental-health support and handover between maternity, HIV and paediatric services.
05Regimens, contraindications and interactionsTreatment details and the circumstances that modify them.
Combination antiretroviral therapy in pregnancy
Continue or start a fully suppressive specialist-selected combination every day; the exact agents and doses depend on resistance, prior therapy, gestation, renal and hepatic function and interactions.Never stop ART abruptly; check antiemetics, supplements, antacids, tuberculosis therapy, anticonvulsants and other interacting medicines, and act urgently on incomplete suppression.
Neonatal antiretroviral prophylaxis
Give the newborn regimen and weight- or gestation-based dose specified by the paediatric HIV team as soon as possible after birth for the assigned risk duration.This is not an adult dose; verify birth weight, gestation, maternal virus and resistance, maternal viral load, feeding exposure and the current paediatric schedule.
06Complications, monitoring and follow-upAdverse effects, response and longer-term review.
- Measure HIV RNA after ART initiation or change and at the BHIVA pregnancy intervals, including a near-term result that is current enough to guide birth.
- Review adherence privately and non-judgementally, checking access, nausea, mental health, coercion, disclosure safety and medicine interactions whenever suppression is incomplete.
- Document the birth-plan thresholds, intrapartum contingencies, neonatal prophylaxis risk category and out-of-hours contacts in records available to the delivery unit.
- Recommend formula feeding because it eliminates postnatal exposure through breast milk. U=U does not apply to breast or chestfeeding: residual transmission risk remains despite viral suppression. Support a suppressed person who chooses breast or chestfeeding non-judgementally through the multidisciplinary team. For supported breast or chestfeeding, use the agreed enhanced maternal and infant virological schedule and review immediately for viraemia, mastitis, nipple bleeding or infant oral disease.
- Complete infant nucleic-acid testing through the relevant post-exposure period and ensure results are actively tracked rather than merely requested.
07Special situationsVariants, exceptions and circumstances that change the usual approach.
Viral load drives transmission risk
CD4 count remains important for maternal health, but the current HIV RNA level and its trajectory determine HIV-specific birth planning.
Thresholds are not interchangeable
Below 50, 50–399 and at least 400 copies/mL carry distinct BHIVA 2025 recommendations rather than one generic detectable category.
Suppression does not erase feeding exposure
Undetectable maternal HIV RNA greatly reduces risk, while formula uniquely removes continuing breast-milk exposure after birth.
A plan can expire
New labour, membrane rupture, missed ART, seroconversion or a later viral-load result requires the delivery and neonatal plan to be rewritten.
Infant antibody is misleading early
Maternal HIV antibody crosses the placenta, so early infant diagnosis relies on virological testing rather than a routine antibody result.
08Common pitfallsFrequent interpretation and management errors.
- 01
Using a CD4 result or an old viral load to choose mode of birth.
- 02
Stopping effective ART because pregnancy is discovered or nausea develops.
- 03
Describing breastfeeding with suppression as either zero risk or categorically forbidden.
- 04
Forgetting that neonatal prophylaxis is time critical and risk stratified.
- 05
Allowing HIV concerns to delay an obstetrically necessary emergency intervention.