Participants
Pregnant women were eligible to participate if they were 18 years or older and between 24 and 28 weeks of gestation calculated using date of last menstrual period and/or earliest obstetric ultrasound scan where available. Women were excluded if they had one or more of the following exclusion criteria: known diagnosis of diabetes, significant medical comorbidity (such as heart failure, renal disease, severe anaemia), multiple pregnancy, inability to provide informed consent, or plans to deliver at a non-study facility.
Women were approached in the antenatal clinic by the research team and screened for inclusion and exclusion criteria.
At recruitment, standardised questionnaires were used  to collect data on socio-demographic and lifestyle factors (including age, level of education, smoking status and alcohol use). Questionnaires also covered family, medical (including HIV status) and reproductive history (parity, gravidity and complications in prior pregnancies). Weight, height, and mid-upper-arm circumference were measured using calibrated Seca scales, stadiometers, and flexible tape measures. After 30 minutes of rest, three seated blood pressure measurements, with 5 minutes rest in between, were collected on the right arm using portable sphygmomanometers (OMRON-Healthcare-Co HEM-7211-E-Model-M6; Kyoto, Japan). We used the mean of the last two blood pressure readings.