Postnatal assessments were done 6 months postpartum, during which a questionnaire identical to that completed at enrolment was filled in and scored. Participants also answered questions with respect to use of contraception, compliance with infant vaccination schedules, and duration of breastfeeding. Answers were verified against an independent source: contraception use was checked by reference to pill packets, family doctor or family planning clinic prescriptions, and appointments; breastfeeding data were validated against medical records; and immunisation data were checked against the National Immunisation Register and Child Health Books, which contain the serial numbers of each administered vaccination.