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Mom's Diet May Influence Her Baby's Sex

Study Shows Women Who Eat Breakfast Cereals Give Birth to More Boys
By
WebMD Health News
Reviewed by Louise Chang, MD

April 22, 2008 -- In addition to being the most important meal of the day, breakfast may help determine your unborn baby's sex.

In a newly reported study, women who ate breakfast cereal gave birth to more boys, while those who skipped breakfast had more girls.

Women who ate more total calories also delivered more boys, even though the overall male-to-female birth ratio among the study participants was close to 50/50.

The early findings in no way prove that what a woman does or doesn't eat prior to conception influences her baby's sex.

But they do hint at a sex-selection bias among humans similar to that seen in other animals, favoring male births among well-fed mothers and female births among mothers who are less well nourished.

They may also help explain a subtle decline in the proportion of male births in industrialized countries like the U.S., researcher Fiona Mathews, PhD, tells WebMD.

"It is true that there is an obesity epidemic, but there is also an increase in dieting and very unstable dietary habits among young women," she says. "And more people are skipping breakfast. Our data suggest that these things may play a role in the small but noticeable decline in male births."

(What was your diet like at the time you conceived? Will you find out the sex of your baby? Talk with others on WebMD's Pregnancy: 1st Trimester message board.)

Fewer Calories, Fewer Boys

The study involved 740 newly pregnant British women who had not given birth before and who did not know the sex of their fetuses. All the women were white, non-obese, and had no medical problems.

The women completed detailed food-frequency questionnaires during the first pregnancy exam and well into their pregnancy, and they were asked to keep a detailed food journal for a week around the time of their fourth month of pregnancy.

They were also asked to recall their dietary habits in the year prior to conceiving.

Using this data, the researchers determined that women who ate the most calories around the time of conception delivered more boys, with 56% giving birth to male babies, compared with 45% of women who ate the fewest calories prior to conceiving.

Of those who reported eating breakfast cereal every day, 59% gave birth to boys compared with 43% of women who reported rarely or never eating cereal for breakfast, says Mathews.

In addition to consuming more calories prior to conception, women who gave birth to boys were also more likely to have eaten higher-quality diets with a wider range of nutrients, including potassium.

If nutrition does affect fetal sex selection, Mathews says it is not clear whether it is calories or nutrients that makes the difference.

What the mothers ate during pregnancy did not seem to influence the sex of their babies.

"The mothers who had boys took in about 300 milligrams more of potassium and about 180 more calories a day than the mothers of girls," she says. "That is the equivalent of a large banana."

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