Gene link to breastfeed crisis

Tests on mice found a specific gene was needed for them to be able to lactate.

The US researchers said the discovery could offer a genetic basis for breastfeeding problems, which are experienced by around 5% of women.

UK breastfeeding experts say some women experience problems, not because of genetics, but because they are not shown the best way to breastfeed their babies - and so give up.

Starvation

The team from the University of Utah and the Department of Veterans Affairs Medical Center found a gene called xanthine oxidoreductase (XOR) is essential for mice to lactate.

XOR is present in almost all cells in the body and it triggers the production of a protein needed for a metabolic process which is essential for cells to survive.

" You see women holding the baby at right angles to the breast rather than having the baby facing them "
Rosie Dodds, National Childbirth Trust

But high levels also begin to be expressed in breast tissue late in pregnancy.

Researchers genetically engineered mice so either one or both copies of the XOR gene were faulty.

The mice with two faulty genes died by six weeks of age, as expected.

Mice with one faulty gene appeared normal.

But their pups all died by the time they were 12 days old.

They died because they were starving, due to their mother's inability to feed them.

The researchers, led by Dr Mario Capecchi, also discovered the XOR protein is needed so the females can secrete fat into milk to feed their newborns.

They said their research lent "important molecular insight into the process of lactation, and suggests that human females with mutations in the XOR gene may be potential candidates for lactation insufficiencies".

'Mummy to tummy'

Rosie Dodds, policy research advisor for the National Childbirth Trust, told BBC News Online: "A huge proportion of women in the UK have problems.

"We know that 70% of women start to breast feed, but around a third have stopped by the time their baby's six weeks old.

"Around 12% stop even before they have left hospital."

She added: "But we think that's mainly because they don't see other women breastfeeding and don't have embodied knowledge about the way that babies feed normally.

"You see women holding the baby at right angles to the breast rather than having the baby facing them - 'mummy to tummy'."

She added: "Women also stop in the early days because they have sore nipples, usually because the baby is not in the right position, for them or their mother."