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Brazilian supermodel Gisele Bundchen's recent comments that all women should be required by law to breastfeed have sparked a heated debate about the benefits of breastfeeding newborns over using formula.

Most new mothers in the United States breastfeed their children, as 75 percent of mothers report having breastfed at some point. About 43 percent choose to continue breastfeeding for six months, and 22 percent continue until the infant is 12 months old, according to data from the 2007 National Immunization Survey released by the Centers for Disease Control and Prevention.

There are several reasons why a mother may choose to bottle-feed her baby instead, as breastfeeding and formula both pose their own unique challenges and conveniences.

Why would a mother choose to bottle-feed?

Bottle-feeding can allow new mothers to be less restrictive with their diets, as they might be concerned that the food and medication that they ingest can be passed along to their babies through their milk. Women who worry that their smoking or coffee habits may make their natural milk contain trace amounts of nicotine and caffeine see baby formula as a safer alternative.

"Breastfeeding mothers should avoid the use of alcoholic beverages, because alcohol is concentrated in breast milk and its use can inhibit milk production," according to the American Academy of Pediatrics. "An occasional celebratory single, small alcoholic drink is acceptable, but breastfeeding should be avoided for two hours after the drink."

Infection is another reason why a woman might choose to stop breastfeeding or avoid it altogether. Mastitis, an infection of the breast tissue that results in breast pain and swelling, can occur in breastfeeding women. It most commonly affects women during the first three months of breastfeeding, according to the Mayo Clinic.

Breastfeeding affects different women differently. Some mothers find it leaves them feeling too uncomfortable and sore, and bottle-feeding offers them a convenient and pain-free alternative. Others choose not to breastfeed because of other family or job pressures.

Why would a mother want to breastfeed?

Breast milk provides newborns with the best combination of antibodies, vitamins, proteins other nutrients for the baby's health and cognitive and physical development, according to the American Academy of Pediatrics. The APA recommends exclusively breastfeeding a newborn for at least the first six months of life, followed by at least another six months of combining breast milk with other sources of nutrition, such as formula.

Studies have shown that breast milk is easier for babies to digest than formula, and can offer various health benefits, from increased immunity and slightly higher intelligence quotients to a decreased risk of sudden infant death syndrome (SIDS).

And the effects seem to last as a child grows. According to 2010 study in the journal Pediatrics, breastfeeding prevents many illnesses that can affect young children, including stomach viruses, ear infections, asthma, juvenile diabetes and even childhood leukemia.

However, researchers at the Norwegian University of Science and Technology have found that the association between breastfeeding and healthy children may not be as strong as previously believed, according to a 2010 study published in the Norwegian journal Acta Obstestricia and Gynecologia Scandinavica. The researchers concluded that it is hormonal levels within the womb that determine the child's future health, and that these hormones also influence a mother's ability to breastfeed after the baby is born.

This article was provided by Life's Little Mysteries, a sister site to LiveScience.