Mothers who choose to breastfeed their children beyond 1 year of age are usually motivated by health and nutrition benefits, according to a recent study.

Researchers found that mothers who breastfeed older babies consider their child's physical and social development to be most important, while the advice of health care professionals, family and friends are least important,

"The three most important reasons that mothers gave for extended nursing were the nutritional benefits of breast milk, the other health benefits of breast milk and the opportunity to build a stronger social bond with their baby," said Alexis Tchaconas, principal investigator of the study and research assistant.

For the study, researchers surveyed more than 50,000 American women between the ages of 18 and 50.

The investigators designed an online survey that asked mothers to rank 15 factors related to extended breastfeeding as "very important," "important," "somewhat important" or "not important." Surveys were sent to mothers via email lists from La Leche League, an international breastfeeding support organization, as well as Facebook groups and online chat rooms dedicated to breastfeeding support.

They found that besides health benefits and bonding with their child, other top factors that influenced mothers to breastfeed beyond one year included enjoyment, support from spouse or partner, La Leche League support and not having to pay for formula.

"Although most women felt comfortable discussing their decision to nurse their baby beyond 1 year of age with their child's pediatrician and with their own health care providers, the recommendations of these health care professionals were not identified as being important in terms of the mother's decision to extend nursing," Andrew Adesman, senior investigator of the study, said in a statement.

The findings will be presented Monday, Oct. 13 at the American Academy of Pediatrics (AAP) National Conference & Exhibition in San Diego.