Breastfeeding a potent painkiller for infants: study

April 2, 2002 - Reuters

CHICAGO - Breastfeeding eases a baby’s discomfort during a painful needle stick procedure and might work as a potent painkiller during potentially traumatizing experiences such as circumcision, researchers said yesterday.

Infants who were held and breastfed while undergoing a painful heel lance, a routine hospital procedure used to obtain a blood sample, cried and grimaced less and their heartbeats remained calmer than infants who were not breastfed, a University of Chicago study said.

"Breastfeeding is a potent analgesic intervention in newborns during a standard blood collection," study author Larry Gray of the University of Chicago wrote in this month’s issue of the journal Pediatrics.

Previous animal studies have shown tastes and flavours in breastmilk can block pain signals in the spinal cord, and suckling can have a calming effect. The researchers said infants' physical contact with their mothers likely also kept them calmer.

There is a debate about whether babies retain memories of single, intensely painful experiences such as circumcision, but some circumcised infants do manifest exaggerated reactions to a needle stick months later.

"The claim can no longer be made that newborn pain is for the moment only," Gray wrote.

In another study in the same journal on the subject of breastfeeding, researchers at the University of New Hampshire in Durham examined the hypothesis that a mother who exercises might produce less appetizing breastmilk.

A previous study found lactic acid levels in breastmilk 30 minutes after a strenuous treadmill test were high enough to deter some babies from drinking it.

In the latest study, researchers waited an hour after exercise before obtaining expressed breastmilk, and also compared milk produced after moderate exercise.

Strenuous exercise did raise the level of lactic acid in the mothers' breastmilk, but their babies showed no sign of rejecting the milk, researcher Timothy Quinn wrote. Moderate exercise did not produce higher lactic acid levels.