title: Mother-to-child transmission of HIV-1 infection during exclusive breastfeeding in the first 6 months of life: an intervention cohort study.
abstract: BACKGROUND
  Exclusive breastfeeding, though better than other forms of infant feeding and associated with improved child survival, is uncommon. We assessed the HIV-1 transmission risks and survival associated with exclusive breastfeeding and other types of infant feeding.
  
  
  METHODS
  2722 HIV-infected and uninfected pregnant women attending antenatal clinics in KwaZulu Natal, South Africa (seven rural, one semiurban, and one urban), were enrolled into a non-randomised intervention cohort study. Infant feeding data were obtained every week from mothers, and blood samples from infants were taken monthly at clinics to establish HIV infection status. Kaplan-Meier analyses conditional on exclusive breastfeeding were used to estimate transmission risks at 6 weeks and 22 weeks of age, and Cox's proportional hazard was used to quantify associations with maternal and infant factors.
  
  
  RESULTS
  1132 of 1372 (83%) infants born to HIV-infected mothers initiated exclusive breastfeeding from birth. Of 1276 infants with complete feeding data, median duration of cumulative exclusive breastfeeding was 159 days (first quartile [Q1] to third quartile [Q3], 122-174 days). 14.1% (95% CI 12.0-16.4) of exclusively breastfed infants were infected with HIV-1 by age 6 weeks and 19.5% (17.0-22.4) by 6 months; risk was significantly associated with maternal CD4-cell counts below 200 cells per muL (adjusted hazard ratio [HR] 3.79; 2.35-6.12) and birthweight less than 2500 g (1.81, 1.07-3.06). Kaplan-Meier estimated risk of acquisition of infection at 6 months of age was 4.04% (2.29-5.76). Breastfed infants who also received solids were significantly more likely to acquire infection than were exclusively breastfed children (HR 10.87, 1.51-78.00, p=0.018), as were infants who at 12 weeks received both breastmilk and formula milk (1.82, 0.98-3.36, p=0.057). Cumulative 3-month mortality in exclusively breastfed infants was 6.1% (4.74-7.92) versus 15.1% (7.63-28.73) in infants given replacement feeds (HR 2.06, 1.00-4.27, p=0.051).
  
  
  CONCLUSIONS
  The association between mixed breastfeeding and increased HIV transmission risk, together with evidence that exclusive breastfeeding can be successfully supported in HIV-infected women, warrant revision of the present UNICEF, WHO, and UNAIDS infant feeding guidelines.
authors.affiliation: Centre for HIV/AIDS Networking, University of KwaZulu-Natal, South Africa.
authors.forename: Hoosen M
authors.initials: HM
authors.lastname: Coovadia
authors.forename: Nigel C
authors.initials: NC
authors.lastname: Rollins
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Bland
authors.forename: Kirsty
authors.initials: K
authors.lastname: Little
authors.forename: Anna
authors.initials: A
authors.lastname: Coutsoudis
authors.forename: Michael L
authors.initials: ML
authors.lastname: Bennish
authors.forename: Marie-Louise
authors.initials: ML
authors.lastname: Newell
mesh_terms: D000293:Adolescent; D000328:Adult; D001942:Breast Feeding; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000401:mortality / Q000635:transmission*; D015497:HIV-1; D006801:Humans; D007223:Infant; D007225:Infant Food / Q000009:adverse effects*; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical / Q000706:statistics & numerical data*; D011247:Pregnancy; D016016:Proportional Hazards Models; D013019:South Africa