HIV: Reducing vertical transmission from the obstetric viewpoint (Abstract)
Zoe Penn, Consultant Obstetrician, Chelsea and Westminster Hospital London.
Pregnant women who are HIV positive are a growing challenge, especially in large urban areas. Some of them already know their status and may have conceived on highly active antiretroviral therapy (HAART), while increasingly others are first diagnosed in pregnancy. Many women are recent refugees to the UK who have multiple associated social and cultural problems apart from their HIV status. All these women need a team approach to optimise their care.
The team should comprise an obstetrician, midwife, health adviser, genitourinary medicine physician with a special interest in pregnancy, a paediatrician and a specialist paediatric nurse. Appointments need to be synchronised, or a special combined clinic needs to be offered. When women prefer to separate their experiences of pregnancy and childbirth from their HIV care communication has to be handled with particular sensitivity.
For women who do not need treatment in their own right the HAART regime, used from mid-pregnancy with the objective of achieving an undetectable viral load at least 4 weeks prior to the scheduled delivery date, optimally reduces the likelihood of mother to child transmission of the virus (vertical transmission). Careful consideration of the mode of delivery, avoidance of breastfeeding and HAART treatment of the neonate for some 4-6 weeks until tests have determined the likely HIV status of the baby are then necessary.
This package of care will in the developed world reduce vertical transmission from approximately 15% to less than 1%.
The major determinant of vertical transmission is the viral load at delivery. If the treatment objective described is achieved there is currently a move to return to vaginal delivery. This should take place with spontaneous onset of labour and without invasive techniques such as artificial rupture of the membranes, fetal scalp sampling or fetal scalp electrode. If any delay is anticipated or encountered, or labour is prolonged or difficult there should be early recourse to caesarean section. The baby should be bathed immediately after birth.
Elective caesarean section is reserved for women who do not achieve an undetectable viral load, in whom the viral load is unknown, at maternal request or for other indications. The place of 'minimal exposure' or 'bloodless' caesarean section is not currently known.
The presence of other infections is known to increase the risk of vertical transmission, so sexual health screening performed at booking and 26 weeks is of great importance. Screening for Down's Syndrome or haemoglobinopathies is also a vexed area since invasive testing is potentially hazardous.
Successful management of these women and their babies relies on good relationships between the woman and her caregivers. Much care and sensitivity should surround privacy, confidentiality and the difficulties many will have with their diagnosis, or the denial to them of breastfeeding or normal birth.