Could the date of your birth doom you to a lifetime of wheezing?
A new study suggests that children who are born in early fall, about four months before the height of the winter cold and flu season, have a 30 per cent higher chance of developing asthma than those born at any other time of year.
"We think this is because it puts them at high risk of getting a serious respiratory virus at a young age," said the lead researcher, Tina Hartert of Vanderbilt University in Nashville, Tenn.
She noted that infants around four months of age are especially vulnerable to wintertime bugs such as respiratory syncytial virus (RSV), which produces typical cold symptoms.
"They have lost their mother's antibodies and they haven't yet developed their own," she explained in an interview. That means if they catch a cold it will probably lead to a serious respiratory infection, which could set the stage for asthma, a potentially life-long lung disease in which the airways occasionally become constricted and inflamed.
The new study, published in the American Journal of Respiratory and Critical Care Medicine, seems to fly in the face of a theory for explaining the rise in childhood asthma cases in recent years.
Known as the "hygiene hypothesis," the theory argues that today's children are not being exposed to enough dirt and germs for the proper development of their immune systems. As a result, their lungs overreact and go into spasm when exposed to minor irritants.
Dr. Hartert says it's possible that both theories can still be correct.
"I think there is a lot to the hygiene hypothesis that is important, but all dirt is not created equal. ... It is too simplistic to lump all dirt and infections into one bag," she said.
The key factor might be the timing of an infection, she said. At a particularly young and vulnerable age, an infection might trigger asthma.
But later, it could foster the healthy development of the immune system.
So, could shielding young infants from certain infections help prevent asthma? "It's a really exciting possibility," but a lot more research would be needed to prove it works, she said.
IVF linked to birth defects
Couples relying on fertility treatments to achieve pregnancy are at an elevated risk of having a child with a birth defect, according to a U.S. study.
The researchers found that several types of birth defects were more common among children conceived through in vitro fertilization, a process involving the uniting of the egg and sperm in a petri dish and implanting the embryo in the womb.
The procedure was associated with twice the normal risk of certain heart defects; more than twice the risk of cleft lips, and four times the risk of some gastrointestinal abnormalities.
Jennita Reefhuis, the lead researcher and an epidemiologist at the U.S. Centers for Disease Control and Prevention, said the overall rate of birth defects is still low even with the fertility treatments.
For instance, one child out of every 950 born in the United States has a cleft lip. With assisted reproductive technology, the number of cleft lips rises to one in every 425 births.
"It is a small risk, but in the interests of full disclosure, I want parents to be aware what it is," said Dr. Reefhuis, whose study was published in the journal Human Reproduction.
"We don't have a very good sense yet of what part of the procedure may be responsible for the elevated risk," she said. But it's possible that couples with fertility problems are also more likely to have offspring with a defect. So, it might not necessarily be the procedure that boosts the risk of birth abnormalities.
FOOD URGES
Got an irresistible urge to eat a sweet chocolate treat? Go for an energetic walk and the desire will pass, according to researchers at the University of Exeter in Britain.
Previous studies have demonstrated the power of exercise to help people triumph over their addictions, including nicotine and drug dependencies.
New research involving 25 habitual chocolate eaters shows that short bursts of physical activity can be used to control food cravings, too.
What's more, the strategy can be used in a pro-active fashion - before the urge to eat strikes. In the experiment, volunteers went for a 15-minute brisk walk and then were tempted with a chocolate bar. Their urge to consume it was less than if they were sedentary before being presented with the treat.
The researchers, led by Adrian Taylor, speculate that exercise triggers the release of chemicals that boost our mood so we are less likely to seek solace in comfort foods.
Incorporating a few exercise breaks into the day may help keep food cravings at bay, the researchers conclude in their study published in the journal Appetite.