Have an older brother or sister? Thank your mother for not having you first. In a study published in the American Journal of Epidemiology, researchers discovered that firstborn babies had higher levels of IgE, an antibody associated with allergies, than subsequent children. Of the nearly 1,000 babies studied, those with high levels of IgE also showed greater susceptibility to allergies at four years of age. Researchers suspect changes in a woman's body during her first pregnancy, including endocrine responses to environmental factors, may explain the results of the study.

Pregnant women with worsening periodontal disease have five times the risk of delivering preterm than women whose gum disease is under control, according to study results presented at the annual meeting of the Infectious Diseases Society for Obstetrics and Gynecology and reported in Family Practice News. Of 88 pregnant women with the disease, those with a worsening form had a 47 percent likelihood of delivering early compared to a 27 percent likelihood in women with a stable form of the disease.

Who would have guessed it? Space travel disrupts our natural rhythms and could mean poor sleep for astronauts on long-distance journeys. In a study published in Psychosomatic Medicine, researchers studied the sleep patterns of an American astronaut who spent five months on the now-defunct space station Mir. After the first three months of the mission, the astronaut slept less and woke up more often, suggesting that the human body's endogenous circadian pacemaker, a part of the brain that controls sleep and wakefulness, is inextricably linked to the Earth's own cycle.

Here are some statistics to think about before hitting the highway. The report “Strategic Highway Research: Saving Lives, Reducing Congestion, Improving Quality of Life,” presented by the Transportation Board of the National Research Council, compares highway fatalities with deaths that take place off the road. While someone is murdered every 34 minutes, in half that time someone dies in a highway crash. In 1998, fewer than 700 people died in U.S. airplane crashes while more than 41,000 died in traffic wrecks.

What's this? A food that's good for you that also tastes good? Results of a study of lab rats published in Time shows that eating two cups of black raspberries daily may ward off esophageal cancer. Raspberries contain anthocyanins, and minerals and vitamins that are anticarcinogenic. Other berries, such as strawberries, can be combined with raspberries for the same good-tasting, good-for-you effect.

Coffee mugs up…A study published in Women's Health shows that a morning cup of coffee may protect you from Parkinson's disease. The 10- to 16-year study shows an inverse relationship between coffee consumption and the risk of Parkinson's disease in men. In women, the study shows a U-shaped correlation between coffee intake and risk of Parkinson's disease, with the lowest risk occurring in those who drink one to three cups of coffee a day. However, when analyzing other sources of caffeine besides coffee, the study found that caffeine remained a major influence in men but not in women.

According to study results published in The Lancet, performing ultrasonography of the fetal profile at 11 to 14 weeks' gestation immediately before karyotyping for chromosomal abnormalities can determine whether a fetus will be born with Down syndrome. The study showed that at 11 to 14 weeks' gestation, the nasal bone is visible in 99.5 percent of chromosomally normal fetuses. It was not visible in 73 percent of trisomy 21 fetuses. The bone may not be present in these fetuses because of hypoplasia or delayed nossification of the bone itself.