1. Department of Obstetrics and Gynaecology, School of Medicine, The University of Zambia, Lusaka 10101, Zambia
2. Women and Newborn Hospital, University Teaching Hospitals, Nationalist Road, Ridgeway, Lusaka 10101, Zambia
3. School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 3193, South Africa
4. Clinical HIV Research Unit, Helen Joseph Hospital, Johannesburg 2193, South Africa
5. Department of Pharmacy, School of Health Sciences, University of Zambia, Lusaka 10101, Zambia
6. Department of Public Health Medicine, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg 2193, South Africa