Most babies with flat heads have something called positional plagiocephaly. The various “Back to Sleep” campaigns which have happily reduced the incidence of cot deaths have also led to 5-48% of newborns ending up with a rather flat back of their head. The easiest way to sort this out is for your baby to spend more time on his/her front when awake.
Attempting to remould babies’ heads with LOCbands or helmets is still a controversial area with little evidence behind the wearing of a helmet for many hours a day for many weeks. They are not available on the NHS as far as I am aware. There are some private clinics in London who offer this service but, for the moment, I think I would agree with the sentiments expressed in Great Ormond Street Hospital’s patient/parent information sheet available at http://www.gosh.nhs.uk/gosh_families/information_sheets/plagiocephaly/plagiocephaly_families.html#diagnosed.
Very occasionally there is a bit more to it than positional plagiocephaly. A baby’s skull is made up of a number of bones which, in order to allow the brain to grow, are not fully joined up when they are born. The edges of these bones, where they touch and will eventually fuse with, another of the skull bones are called “sutures”. Sometimes they appear as ridges when the baby is first born. These ridges should have gone by your baby’s 6 week check. Very rarely one or more of these sutures fuse too early and this can lead to your baby having a noticeably asymmetric head, a condition called craniosynostosis. Your baby’s paediatrician will be able to discuss possible causes of this and do further investigations and referrals if necessary.