Prevention of mother-to-child transmission services are integrated into antenatal care in South Africa, but post-birth care is at HIV clinics. Almost all Mothers Living with HIV (MLH) in 24 township neighborhoods (N = 324) reported engagement in HIV care from pregnancy to 36 months post-birth. Less than half re-engaged in HIV care at 6 months (45%), 52.5% at 18 months, and 62.5% at 36 months. Most were prescribed antiretroviral drugs if re-engaged in care, yet only about half (53%) are on antiretroviral drugs at 36 months post-birth. Implementation of Option B+ will require substantially better engagement in care.