title: Population-level impact of hormonal contraception on incidence of HIV infection and pregnancy in women in Durban, South Africa.
abstract: OBJECTIVE
  To estimate the potential impact of using hormonal contraceptives on rates of infection with human immunodeficiency virus type 1 (HIV-1) and pregnancy by theoretically removing the use of hormonal contraceptives from a study population.
  
  
  METHODS
  A prospective cohort study included 3704 HIV-negative women who were enrolled in two biomedical trials that tested two vaginal microbicides (PRO 2000 and Carraguard®) for the prevention of HIV-1 in Durban, South Africa, in 2004-2009. Cox proportional hazards regression models along with partial population attributable risks (PARs) and their 95% confidence intervals (CIs) were calculated to assess the relative population-level impact of the use of hormonal contraceptives on HIV-1 seroconversion rates and on pregnancy rates.
  
  
  RESULTS
  Women who reported using hormonal contraceptives at enrolment in the trial had a higher risk of HIV-1 seroconversion (adjusted hazards ratio: 1.24; 95% CI: 0.97-1.58) than women who reported using other types of contraceptives at enrolment. At the population level, the use of hormonal contraceptives (pills or injectables) at baseline and during study follow-up accounted for approximately 20% (95% CI: 16-22) of HIV-1 seroconversions. However, the partial PAR indicated a relative impact of 12% (95% CI: 9.0-15.7). On the other hand, 72% (95% CI: 66-77) of the pregnancies could have been avoided if all women had used hormonal contraceptives.
  
  
  CONCLUSIONS
  Women using hormonal contraceptives need comprehensive counselling on simultaneous prevention of HIV-1 infection.
authors.affiliation: HIV Prevention Research Unit, Medical Research Council, 123 Jan Hofmeyr Road, Westville, Durban, 3630, South Africa. Gita.Ramjee@mrc.ac.za
authors.forename: Gita
authors.initials: G
authors.lastname: Ramjee
authors.forename: Handan
authors.initials: H
authors.lastname: Wand
mesh_terms: D000328:Adult; D017677:Age Distribution; D000890:Anti-Infective Agents / Q000008:administration & dosage; D003278:Contraceptives, Oral, Hormonal / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D004522:Educational Status; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D018023:HIV Seronegativity / Q000187:drug effects*; D006679:HIV Seropositivity / Q000453:epidemiology; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D015994:Incidence; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control; D011247:Pregnancy; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D012725:Sexual Behavior / Q000706:statistics & numerical data; D013019:South Africa / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000890:Anti-Infective Agents; D003278:Contraceptives, Oral, Hormonal