5 Surprising Facts About Pregnancy

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Breast size may predict your baby's gender. Really? Yup! And that's not the only surprising thing we've discovered about pregnancy…

The Scoop

In her book, Do Chocolate Lovers Have Sweeter Babies? Surprising Science of Pregnancy, science writer and mom Jena Pincott dug through tons of prenatal research to come up with a lengthy list of fun and little-known scientific factoids about pregnancy and gender prediction. And she recently shared some of her favorite finds!

The Discoveries

• You are sexier when you are pregnant: Worried that your rounder shape makes you less desirable to your mate? The opposite may be true. In one study unearthed by Pincott, 60 percent of men maintained the same level of sexual desire for their partners, but 27 percent of men thought their partners were actually sexier while pregnant.

• Breast size may predict your baby's gender: If you become particularly well-endowed during pregnancy, it could be a telltale sign that you are having a girl. According to a study conducted in Poland, moms-to-be carrying girls tend to grow larger breasts during pregnancy compared to those carrying boys. Pincott found that boy babies already produce testosterone in utero, which could suppress breast enlargement.

• Your intuition may be right more often than not: Had a vivid dream that you are carrying a boy—or going on a gut feeling? A study from Johns Hopkins University found that women who used dreams and emotions to guess their baby's sex were more accurate than predictions made by chance, Pincott reports.

• Thin women tend to have girls: Looking at birth statistics from 1997 to 2001, Pincott found that underweight women tended to have more girls more than boys. The reasoning, according to one study she found, is that female embryos are able to survive in a "harsh environment" where fewer nutrients are available than boy embryos are. This is just an observation, Pincott notes, and not the green light to starve yourself for the sake of having a girl.

• Your hormones prepare your guy for fatherhood: It's no secret that pregnant women step up production of chemical compounds in their sweat called pheromones—some theories say the subtle odor let off by the compounds help babies to identify their mothers at birth. But pheromones may also trigger hormonal changes in your partner. In one study, men saw a lift in their prolactin levels after spending time with their pregnant mates and researchers say it was set off by the scent of pheromones. Men with higher prolactin levels are thought to be more nurturing than men with lower levels of the hormone—perfect for when there's a baby on the way!