Recent research suggests that when moms-to-be eat apples during pregnancy, their offspring have lower rates of asthma.

And, mothers who consume fish during pregnancy may lower their child's risk of developing the allergic skin condition called eczema.

"There are influences that occur in utero that can have lasting impact," said Dr. Jennifer Appleyard, chief of allergy and immunology at St. John Hospital and Medical Center in Detroit. "More and more, we're finding influences for later health develop earlier than we anticipated."

More than 20 million Americans have asthma, according to the U.S. Centers for Disease Control and Prevention, and about 6.2 million of those are children.

Eczema is an allergic condition that makes the skin dry and itchy. It's most common in babies and children and is sometimes called atopic dermatitis.

Dutch researchers recently followed 1,253 children from before birth to age 5. Their mothers completed food questionnaires during their pregnancies, and their children's health was assessed with a symptom questionnaire. The children's diets were also assessed.

Women who consumed the most apples during pregnancy -- more than four a week -- had children who were 37 percent less likely to have ever wheezed than children of mothers who had the lowest consumption of apples during pregnancy. Additionally, youngsters born to apple-loving moms were 46 percent less likely to have asthma symptoms and 53 percent less likely to have doctor-confirmed asthma than those whose mothers shunned the fruit.

The mechanism behind apples' apparent protective effect needs further study, but may have something to do with the flavonoids and other antioxidants contained in apples, said Dr. Devang Doshi, director of pediatric allergy and immunology at Beaumont Hospital in Royal Oak, Mich.

The study, published in the journal Thorax, also found that mothers who ate fish more than once a week had children who were 43 percent less likely to have eczema than women who never ate fish.

"This was a good study, but we need a lot more evidence still," said Doshi, who pointed out that the children in the study generally had well-balanced, nutritious diets, and that may have played a role as well.

So, what's a pregnant woman to do? "The general consensus is that women should consume a good, well-balanced diet with lots of fruits and vegetables, and not to overindulge in any one food," he said.

Appleyard recommends avoiding nuts, peanuts and shellfish while you're pregnant to reduce the risk of your child developing a food allergy.

While this advice applies to everyone, it may be even more important for those with a family history of allergies. And Appleyard added that women who are vegetarians have to weigh the risks and benefits of following such dietary restrictions.

She agreed that prenatal nutrition is an area that needs a lot more research but suggested that pregnant women might want to "pick your foods wisely, because what you're eating today may not only nourish your body, but may have an impact on your baby's future health."

Appleyard added that for preventing asthma, avoiding cigarette smoke both before and after birth is crucial.