title: Differences in fertility by HIV serostatus and adjusted HIV prevalence data from an antenatal clinic in northern Uganda.
abstract: OBJECTIVE
  To estimate differences in fertility by HIV serostatus and to validate an adjustment method for estimating the HIV prevalence in the general female population using data from an antenatal clinic.
  
  
  METHODS
  We used Cox regression models to retrospectively estimate the age-specific relative fertility (RF) of HIV-positive compared to HIV-negative women among 3314 antenatal clinic attenders in northern Uganda. RF and the age distribution of women in the general female population were used to extrapolate the antenatal clinic-based HIV prevalence. This procedure was indirectly validated by comparing the adjusted estimate with those based on standard adjustment factors derived from general female populations in Uganda and Tanzania.
  
  
  RESULTS
  HIV-positive women reported a lower fertility than HIV-negative women [age-adjusted RF=0.83, 95% confidence interval (CI): 0.75-0.93]. Except for girls aged 15-19 (RF=0.96, 95% CI: 0.74-1.24) HIV-positive women in all age groups were less fertile (20-24 year: RF=0.83, 95% CI: 0.67-1.01; 25-29 years: RF=0.79, 95% CI: 0.62-1.00; 30-49 year: RF=0.79, 95% CI: 0.65-0.96]. Adjusting the antenatal clinic-based HIV prevalence (11.6%) for these differences yields a higher estimate (13.8%) that is lower than those based on standard adjustment factors derived from general female populations (from 14.6% to 17.7%).
  
  
  CONCLUSIONS
  The age-specific pattern of differential fertility by HIV serostatus derived from antenatal clinic data is consistent with findings from population-based studies conducted in Africa. However, differences in fertility between HIV positive and HIV-negative clients underestimate those in the general female population yielding inaccurate estimates when used to extrapolate the HIV prevalence.
authors.affiliation: National Centre for Epidemiology, Surveillance and Health Promotion, Istituto Superiore di Sanità, Rome, Italy. fabiani@iss.it
authors.forename: Massimo
authors.initials: M
authors.lastname: Fabiani
authors.forename: Barbara
authors.initials: B
authors.lastname: Nattabi
authors.forename: Emingtone O
authors.initials: EO
authors.lastname: Ayella
authors.forename: Martin
authors.initials: M
authors.lastname: Ogwang
authors.forename: Silvia
authors.initials: S
authors.lastname: Declich
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005298:Fertility / Q000502:physiology*; D015658:HIV Infections / Q000453:epidemiology / Q000503:physiopathology*; D018023:HIV Seronegativity / Q000502:physiology; D006679:HIV Seropositivity / Q000453:epidemiology / Q000503:physiopathology; D006801:Humans; D011159:Population Surveillance / Q000379:methods; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology / Q000503:physiopathology; D011295:Prenatal Care / Q000379:methods; D015995:Prevalence; D012189:Retrospective Studies; D014454:Uganda / Q000453:epidemiology