Loss to Follow-Up After Pregnancy Among Sub-Saharan Africa-Born Women Living With Human Immunodeficiency Virus in England, Wales and Northern Ireland: Results From a Large National Cohort.

Between 1200 and 1400 pregnancies are reported in the United Kingdom and Ireland each year among women with diagnosed human immunodeficiency virus (HIV) infection,1 most of whom have migrated from sub-Saharan Africa.2 The UK and Ireland have a successful program for the prevention of vertical transmission of HIV, with a vertical transmission rate of approximately 0.5%.3 Women living with HIV receive antenatal care free of charge, with care usually provided by a multidisciplinary team including specialist staff from HIV medicine, obstetrics and pediatrics, and the voluntary sector. Sustained engagement with HIV services is important after pregnancy, safeguarding women's health, as well as potentially reducing the risk of unplanned pregnancy and onward transmission of HIV through the provision of contraception and antiretroviral therapy (ART). Discontinuation of ART postpartum has been associated with adverse outcomes, such as detectable viral load at delivery in subsequent pregnancies,4 and increased morbidity and mortality.5 However, early engagement with HIV services postpartum has been shown to be associated with virologic suppression in the longer term.6 Current UK standards of care for people living with HIV state that >95% of patients should access services at least annually.7 Studies conducted in the UK looking at loss to follow-up (LTFU) at 1 year among HIV-positive adults have reported rates ranging from 2.5% to 20%, with female sex, younger age, recent diagnosis of HIV, and not being on ART associated with an increased risk of disengagement from care.8–10 A consistent finding across these studies is the association between black African ethnicity and LTFU.8–10 Women may face particular challenges in engaging with HIV services after pregnancy. However, few studies have explored LTFU after pregnancy in women living with HIV, and most of those have been conducted in low-income settings, revealing high rates of attrition.11–13 Data on retention in HIV care after pregnancy in high-resource settings are more limited. Studies in the United States have reported attrition rates of between 40% and 60% 1 year after delivery,6,14 whereas a recent analysis of data from the Swiss HIV Cohort Study has revealed a LTFU rate of 12% 1 year postpartum.15 To the best of our knowledge, there are no published data on LTFU after pregnancy in women living with HIV in the United Kingdom. We present one of the largest studies to date in a high-income setting to explore retention in HIV care in women after pregnancy. Specifically, we aim to examine the association between LTFU from HIV care in the calendar year after pregnancy and: (i) maternal ethnicity/region of birth and (ii) maternal duration of residence in the United Kingdom, hypothesizing that migrants, especially those living in the United Kingdom for a shorter time, may encounter particular challenges in accessing ongoing HIV care.