Advice to lie babies on their back for sleep to avoid cot death is having a side-effect - more infants now have a flat head as a result, say experts.
US researchers say the rate of flattened head or plagiocephaly has risen significantly since guidance on the safest sleeping position.
Between 1999 and 2007 the rate increased nine-fold from three to 29 cases per 10,000 live births in Texas.
UK experts say they have also noted a similar trend.
When babies are very young their heads are soft enough to be moulded, which means the shape can be altered by pressure.
Lying on firm mattresses and sitting in car seats and buggies puts pressure on the back of the skull and can lead to a flattened look, say experts.
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