Exclusive Breastfeeding Safer in HIV Mothers

DURBAN, South Africa, March 30 -- When women with HIV exclusively breastfeed their infants for the first six months, the chance of passing on the virus is only about 4%, researchers here said.

But if other milks or solid foods are introduced into the baby's diet during that time, the risk of HIV transmission skyrockets, according to Nigel Rollins, M.D., of the University of KwaZulu-Natal in suburban Congella.

The finding -- from a prospective study of nearly 3,000 women, half of them HIV-positive -- warrant revision of current guidelines that oppose breastfeeding, Dr. Rollins and colleagues reported in the March 31 issue of The Lancet.

Breastfeeding in HIV has been controversial. On one hand, breastfeeding protects against a range of illness, but at the same time it has a risk of transmitting HIV from an infected mother.

This study shows two things, Dr Rollins said. One is that HIV-infected women are able to breastfeed exclusively for the first six months of a baby's life and that "mixed breastfeeding" -- breastfeeding supplemented with solids or other milks -- is more hazardous in terms of HIV transmission than breastfeeding alone.

Also, the researchers said, the mortality risk of replacement feeding was higher than for exclusive breastfeeding.

The researchers enrolled 2,722 women, 1,372 of them HIV-positive, who gave birth between Oct. 29, 2001 and April 16, 2005 to 2,779 babies. This analysis focused on the HIV-positive women, but all women were given the option of exclusive breastfeeding with skilled support from community workers, replacement feeding with formula, or mixed breastfeeding.

Over the course of the study, Dr, Rollins and colleagues said, many women defaulted to what they called "mixed breastfeeding" -- adding other milk or solids -- but a large proportion maintained exclusive breastfeeding for long periods.

Specifically, 1,132 HIV-positive women started exclusive breastfeeding, compared with 109 who began with replacement feeding and 35 who started with mixed breastfeeding. Of those, 920 breastfed exclusively for at least four weeks, 688 for 14 weeks or more, and 415 for 26 weeks.

Analysis of outcomes found:

• The estimated risk of acquisition of infection at six months was 4.04%.
• Breastfed infants who also received solids were more than 10 times as likely to acquire infection as exclusively breastfed children. The hazard ratio was 10.87, with a 95% confidence interval from 1.51 to 78.00, which was significant at P=0.018.
• Infants who at 12 weeks received both breast milk and formula milk were also at higher risk of infection. The hazard ratio was 1.82, with a 95% confidence interval from 0.98 to 3.36, which was significant at P=0.057.
• Cumulative three-month mortality in exclusively breastfed infants was 6.1%, compared with 15.1% in infants given replacement feeds. The hazard ratio was 2.06, with a 95% confidence interval from 1.00 to 4.27, which was nearly significant at P=0.051.

The study was characterized as a "breakthrough," by Wendy Holmes, MBBS, of the Macfarlane Burnet Institute for Medical Research and Public Health in Melbourne, Australia, and Felicity Savage, MBBCh, of the Center for International Health and Development in London.

It "provides crucial confirmatory evidence that when HIV-positive mothers breastfeed exclusively, their babies have only a low risk of infection with HIV," Drs. Holmes and Savage said in an accompanying commentary.

The study also "adds to the accumulation of new evidence on the hazards of formula feeding," they said.

Translating the finding to community practice in the developing world remains a challenge, they said, noting that the study employed skilled infant-feeding counselors, who are in short supply in most communities.

They concluded that "promoting, protecting, and supporting exclusive breastfeeding to six months has the greatest potential to improve HIV-free child survival."