Parents who sleep alongside their baby in bed or on the sofa could be putting the newborn at risk of sudden infant death syndrome (SIDS), a health advisory body has warned.
But Britain's National Institute for Health and Care Excellence (Nice) stopped short of telling parents to stop the practice, admitting that health professionals are "stuck between a rock and a hard place" because of conflicts over breastfeeding.
Instead, updated guidance published yesterday intends only to make parents aware of an association between co-sleeping with their baby in a bed, on a sofa or on a chair and an increased risk of SIDS up to the age of one year.
The link is greater when a parent, including a partner, smokes, drinks alcohol or takes drugs prior to co-sleeping or if the baby was born prematurely or with a low birth weight.
More than 200 babies in England and Wales die unexpectedly in their sleep every year for no apparent reason, most commonly between the ages of four weeks and 12 weeks.
Prof Mark Baker, Nice's clinical practice director, said he understood the new guidance could be confusing, but believed it was better for parents to make individual decisions about co-sleeping.
"We're not telling people not to co-sleep with their babies, we know that could get in the way with breastfeeding, but there is an association with SIDS and it's better that parents should know," he said.
"We are between a rock and a hard place. The only recommendation we could have made would be to avoid co-sleeping, but it would be seen as incompatible with breastfeeding guidelines."
Elaine McInnes, a development officer with the Institute of Health Visiting, said professionals should discuss safe sleeping arrangements with parents before the baby is born.
"Being a new parent is exhausting. We know many new mothers and fathers will, at some point, fall asleep with their newborn and parents should not feel guilty or embarrassed," she said.
Experts say the safest way for a baby to sleep is on its back, in its cot or Moses basket in the parents' room for the first six months.