The investigators will conduct an observational cohort study in 1200 pregnant women who will be recruited at the first antenatal care (ANC) visit from the Gugulethu and one additional facility in the Klipfontein-Mitchell's Plain subdistrict of the Metro Region (to be identified in conjunction with provincial and local health authorities) Midwife Obstetric Units in Cape Town (n=600 pregnant women per site). The enrolled women will be followed through 12-months post-delivery.

The objectives of the study are to:

1. Determine the distribution of women across the PrEP cascade:

1. Evaluate the proportion of pregnant and breastfeeding women who initiate PrEP out of all women offered PrEP
2. Evaluate the proportion of pregnant and breastfeeding women who are retained in the PrEP cohort
3. Evaluate the proportion of pregnant and breastfeeding women who initiate PrEP who adhere to PrEP using objective dried blood spot measures and subjective measures of self-reported pill count and adherence
4. Evaluate the proportion of pregnant and breastfeeding women on PrEP (and not on PrEP) who acquire HIV, who transmit HIV to their infant, and who report adverse events 2. Evaluate patient and provider-level factors associated with the PrEP cascade using quantitative and qualitative approaches (including in-depth interviews) 3. Apply an established mathematical model to simulate the impact of improvement in the PrEP cascade on HIV infections averted (maternal and perinatal)

Inclusion Criteria:

• >16 years of age,
• confirmed HIV-negative (using 2 rapid tests,
• confirmed with a 4th generation antigen HIV test;
• lives within 20 km. of the clinic;
• confirmed to be pregnant;
• without psychiatric or medical contraindications to PrEP

Exclusion Criteria:

• Concurrent enrollment in another HIV-1 vaccine or prevention trial;
• medical hospitalization in the past year for any reason;
• receipt of TB treatment in the past 30 days; history of renal disease;
• exhibiting psychotic symptoms (including hallucinations, suicidal or homicidal ideation, or violent behavior),
• currently or history of taking anti-psychotic medications;
• positive Hepatitis B surface antigen test on screening;
• history of bone fracture not related to trauma;
• any other medical, psychiatric, or social condition which in the opinion of the investigators would affect the ability to consent and/or participate in the study.

Study counselors will enroll consecutive eligible, consenting pregnant adolescent girls (>16 years) and women in ANC (n=600 women per site; N=1200 pregnant women) and follow them up for 12-months postpartum or until censorship for a mean of 18-months' follow-up.

In a sub-study, STI and PrEP in Pregnancy Study (STIPPS), we will include n=268 women who recieve point of care STI results vs. those treated syndromically to evaluate PrEP initiation in pregnancy.

Pregnant women in PrEP-PP study

Between Aug 2019 and October 2021, we followed 1195 women and ascertained 1145 pregnancy outcomes, abstracted from maternal case files, infant road to health cards, and local obstetric records.

Miscarriage or pregnancy loss was defined as noninduced pregnancy loss ≤20 weeks (0/7 days) of gestation.

Stillbirth was defined as delivery of a baby with no sign of life >20 weeks (0/7 days) of gestation, including foetal demise.

Neonatal mortality was defined as death of a newborn in the first 28 days of life (days 0-27).

Preterm live birth was defined as birth before completion of 37 weeks (0/7 days) of gestation.

Low birthweight was defined as an infant birthweight <2500 grams.

We originally indicated reporting "Participants Missing Pre-natal Visit" as a Secondary Outcome, however are unable to report as the data is unavailable.