Statistical methods
death, miscarriage, HIV status disclosure
REGRESSION, SECONDARY, MISCARRIAGE, SENSITIVITY
The primary analysis was done on an intention-to-treat basis with all randomly assigned participants. The proportion of mothers or infants retained in care at 18 months postpartum was calculated using Poisson regression with robust standard errors. Sensitivity analyses included adjustment for age (18–24; 25–29; 30–34; 35–44 years), time from HIV diagnosis to enrolment (< 6 months or ≥ 6 months), and site. Additional sensitivity analyses excluded participants with a documented miscarriage, stillbirth, death of the infant or mother, or transfer to another clinic before 18 months postpartum. All adjusted variables and sensitivity analyses were determined a priori.Unadjusted and adjusted analyses of secondary outcomes were similarly conducted. Retention in care between 6 and 12 months postpartum was analysed using the same exclusion criteria. Logistic regression was used to determine whether there were associations between the intervention and adverse birth outcomes (miscarriage or stillbirth) or transfer to another clinic. We used WHO's definitions of miscarriage and stillbirth, in which babies who die before 28 weeks of pregnancy were considered a miscarriage and those who die at or after 28 weeks were considered stillbirthsAfter the study protocol had been published, but prior to data analyses, age (18–24; 25–29; 30–34; 35–44 years of age), education (primary or less; secondary; post-secondary), married or living with a partner (yes/no), time from HIV diagnosis to enrolment (< 6 months or ≥ 6 months), HIV status disclosure (yes/no), travel time to clinic (< 1 h or ≥ 1 h) and site, were selected as variables for subgroup analyses. Subgroups were identified based on pre-existing knowledge of barriers to pregnant women’s participation in PMTCT care. Effect modification by subgroup was assessed by introducing each subgroup separately as an interaction term in the unadjusted intervention effect analysis using Poisson regression with robust standard errors. Statistical analyses were done using StataCorp. 2011 and 2017. 