Cesarean mums breast-feeding stress to babies: New Zealand s

WELLINGTON, Aug. 10 (Xinhua) -- Mothers who give birth through a cesarean section could pass on stress to babies through hormones in breast milk, according to a New Zealand study out Wednesday.

Researchers at the University of Auckland's Liggins Institute analyzed breast milk samples from 650 mothers when their babies were three to four months old.

The findings revealed levels of the stress hormone, cortisol, were higher in the milk of mothers who delivered their babies by cesarean section (c-section) or who had no partner at home.

As well as a major regulator of the body's stress response, cortisol was an important influencer of mood and growth, researcher Shikha Pundir said in a statement.

Cortisol also directed energy towards making fat, not muscle, making it even more vital in early growth and development.

While a certain amount of stress hormones were needed to stimulate healthy development, evidence from animal studies suggested that higher cortisol in milk affected babies' temperaments.

Studies in rodents showed that stress during motherhood emboldened offspring, but primate studies showed that higher cortisol made monkey babies more irritable and nervous, with a similar effect observed in the few human studies done so far.

"These findings reinforce that there are real emotional and biological challenges that face mothers who have undergone a c-section delivery or who don't necessarily have the full support to cope fully with a new baby," said Pundir.

Breast milk was recognised for its nutritional and immunity-boosting powers, but it was still unclear exactly how stress hormones affected babies' growth and development, the researchers said.

The findings underlined the importance of supporting all mothers in order to avoid the transmission of stress to babies, which could potentially have a long-term adverse impact on a baby's health.