I know that there is a higher risk of sudden infant death syndrome (SIDS) when infants are put to sleep on the stomach. But I've noticed that putting babies put to sleep on their backs causes the back of the head to flatten out a bit. I saw this on my own child, who is now two years old, although the proper shape did return. Is this something to worry about? I am pregnant again and wonder whether I should put the baby to sleep on its stomach some of the time. - W.M., Jerusalem Judy Siegel-Itzkovich comments: The American Association of Neurological Surgeons (AANS) reported recently that the incidence of this condition has increased five-fold since the introduction in the US 16 years ago of the "Back to Sleep" campaign launched to cope with the rise in SIDS. "While thousands of lives have been saved through this campaign, more babies have developed positional plagiocephaly, much to the concern of very worried parents," said Dr. Monica Wehby, a pediatric neurosurgeon and AANS spokeswoman. It is not uncommon to have a misshapen head related to the rigors of childbirth, she said, but this usually resolves itself within six weeks. However, some infants develop this condition within the first few months of life, caused primarily by sleeping on one side or the back. Wehby said many parents fear the flatness will be a permanent condition. It's important to bring the baby to a pediatrician when the problem is first noticed. Although the majority of misshapen heads are due to positional plagiocephaly from sleeping on the back, a small number of babies are born with a far more serious form of plagiocephaly caused by craniosynostosis, in which the deformity is caused by premature closure of the fibrous joints between the bones of the infant skull (called cranial sutures). A thorough examination is necessary to confirm or rule out this diagnosis, she said. The AANS says that the risk of positional plagiocephaly can be reduced by simple alternation of the baby's sleeping position and supervised time on the stomach during play. If the head is flatted, place the baby's body with its head turned on the opposite side and put a rolled-up towel or blanket beneath the back and hip on the flattened side, positioning the baby to 45 degrees, she advised. Place interesting objects on the opposite side of the bed to attract the infant's attention. Do not put the towel or blanket under the infant's head, because this can lead to suffocation. As many infants will wiggle off of the roll in a short time, some doctors recommend using Velcro or tape to secure the roll to the infant's body. When holding, feeding or carrying an infant, make sure that there is no undue pressure placed on the flat side of the head. Change the head position from side to side during feeding time. For optimal results, this positional therapy should be started before the infant is four months old. If positional therapy doesn't work, some pediatricians recommend that a helmet or band customized to the baby's head is worn more than 23 hours a day (but not during bathing) from the age of five months and continue for two to six months. The AANS urges parents not to purchase helmets on their own without first consulting a specialist. I have read that frequent fasting is good for your health. Is this true or is such fasting harmful? - R.D., Tel Aviv. Judy Siegel-Itzkovich comments: The Journal of Lipid Research recently discussed this issue. Consuming fewer calories and increasing physical activity is usually what people do to lose weight and stay healthy. But some people prefer to eat as much as they want one day and fast the next. On each fasting day, they take sugar-free beverages, tea, coffee and sugar-free gum and drink as much water as they need. Although many people claim that this diet, called alternate-day fasting (ADF), helps them lose weight and improves their health, its effects on health and disease risk are not clear. The journal presents research by Dr. Krista Varady of the University of California at Berkeley's department of nutritional sciences, who studied the effects of alternate-day fasting on 24 male mice for four weeks. The scientists tested mice that followed and didn't follow an ADF diet as well as those that only partially followed it. One group of mice consumed 50 percent of their regular diet every other day and another 75% every other day. The scientists noticed that the mice that followed the complete ADF diet lost weight and that the fat cells of both those in the 50% group shrank by more than half and by 35 percent respectively. Also, in these two groups of mice, fat under the skin - but not abdominal fat - was broken down more than in mice that did not follow the diet. These results suggest that complete and modified ADF regimens seem to protect against obesity and type 2 diabetes but do not result in fat or weight loss. More studies will be needed to confirm whether the long-term effects of ADF regimens are beneficial for human health and reduce disease risk, the scientists concluded. Rx for Readers welcomes queries from readers about medical problems. Experts will answer those we find most interesting. Write Rx for Readers, The Jerusalem Post, POB 81, Jerusalem 91000, fax your question to Judy Siegel-Itzkovich at (02) 538-9527, or e-mail it to email@example.com, giving your initials, age and residence.