HIV-positive mothers can still pass the virus on by breast-feeding, so they would need to be provided with formula and taught about bottle-feeding.

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After struggling to make breast feeding work, she switched to formula feeding - and instantly felt more bonded to her baby.

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For the trial, Flaherman and her colleagues assigned half the babies a couple days of birth to receive two teaspoons of formula after each breast-feeding, via a syringe so as not to encourage "nipple confusion" in which a baby has trouble transitioning between breast and bottle.

CNN: How formula could increase breast-feeding rates

And at three months, 79% of the formula group was exclusively breast-feeding, significantly more than the 42% of moms in the group originally instructed to breast-feed.

CNN: How formula could increase breast-feeding rates

"This study goes against everything that's been published for several years now from very reliable clinicians and researchers about the potential hazards of supplementing exclusively breast-feeding babies with formula, " says Dr. Kathleen Marinelli, an associate professor of pediatrics at the University of Connecticut School of Medicine and the chair-elect of the U.S. Breastfeeding Committee.

CNN: How formula could increase breast-feeding rates

And if we're going to remove formula samples for women to promote breast-feeding, we better come up with a plan to feed the babies of that 5% of women who can't sustain them -- with 4 million births a year, that's 200, 000 moms who need extra help.

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At one week of age, 10% of the formula group was still using formula in some way as part of their feeding strategy compared to 47% of the group originally assigned to breast-feed but who added formula.

CNN: How formula could increase breast-feeding rates

Breast feeding also resulted in a change in microbes, with formula-fed babies showing more Peptostreptococcaceae bacteria and Clostridium difficile.

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