Study participants and sampling strategy
LBW
RECRUITMENT
Participants in the parent cRCT were identified from maternity registers. Eligible participants were LBW (<2500 g at birth) or PT (gestational age <37 weeks with birth weight <3000 g) infants delivered at one of 17 facilities across the county. A list of potentially eligible infants, alive at 28 days and approaching 6, 12 or 18 months±2 weeks of age was created, with age adjusted for PT status if the infant was born at less than 37 weeks’ gestation. Recruitment was sequential toward the goal sample size across combined cRCT arms, as this follow-up study was not designed to evaluate the impact of the cRCT intervention.A priori calculation of sample size using the Cochran’s method was based on the caregiver-report Ten Questions Questionnaire (TQQ) in a community-based study of PT versus term infants in Malawi.