Many American women might be having their children too close together, finds a new study by the Centers for Disease Control and Prevention (CDC), once again raising questions about the ideal spacing between pregnancies. The report, based on data-crunching of 2011 birth certificates from 26 states and the District of Columbia (representing about 83% of the country's births that year) found that 30% of women who'd had a child got pregnant again within 18 months.

Naturally, it's every woman's prerogative to decide when to have her kids. Most of us know plenty of women who've had kids close together with no negative effects. Kate Middleton—due this month—got pregnant with her second child a little more than 13 months after the birth of Prince George.

As Health.com has reported, research suggests that having pregnancies too close is less than ideal for both mom and baby. Experts believe it's best for a mother's body to have time to recover after carrying and delivering a child.

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Plus, studies have shown that women who wait less than 18 months after giving birth to conceive again are more likely to have a premature delivery, while waiting less than 12 months is associated with a higher risk for complications like placental abruption.

That said, the CDC report concludes that more research is needed to determine whether so-called "inter-pregnancy intervals" are independently related to maternal or infant problems—or whether factors such as mom's age and pregnancy health behaviors come into play. In other words, there might be some risk factor associated with closely spaced pregnancies (such as lack of prenatal care or planning) that is responsible for the link, not the spacing itself.

At 33, Kate is young and healthy. Here's to a joyous, uneventful royal birth. Oh, and if you mind the majority of bets being taken in England, it's a girl.

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