Explainer

Nicole Richie Can Get Pregnant?

How underweight mommies make it happen.

Nicole Richie

Rumors have been swirling for the past few weeks that Nicole Richie—daughter of Lionel, on-again/ off-again BFF of Paris Hilton, and published author —has a bun in the oven. Although Richie’s camp has yet to confirm the pregnancy rumors, tabloid magazines seem to be betting the farm that Richie is about 12 weeks along. But how can someone her size get pregnant?

With difficulty. At the time of her DUI arrest in December, police listed Richie as 5 feet 1 and 85 pounds, which gives her a body mass index of around 16. For women with a BMI of less than 18 or 19 (that would be between 101 and 106 pounds for Richie), the chances of getting pregnant are pretty slim. Women need fat to signal the pituitary gland to ovulate—without it, their bodies go into a kind of famine mode and won’t use up energy to maintain reproductive processes. Women need at least 24 percent body fat to have normal periods; those with between 17 and 24 percent will ovulate irregularly. Someone with less than 17 percent body fat, like an anorexic, will return to a prepubescent state in which she doesn’t ovulate at all. (Richie has denied having an eating disorder, although she was hospitalized last year for an “inability to put on weight.”)

Fertility drugs such as gonadotropins can help underweight women start ovulating again. Doctors say that such treatment is also common among those who lose their periods due to strenuous exercise. Once an underweight woman conceives, though, it’s important that she puts on weight steadily throughout her pregnancy. The average weight gain for mothers is around 28 pounds, and someone of Richie’s height should work to add at least 20. (Miscarriage and other complications are a greater threat for skinny women.)

Bonus Explainer: If Richie were pregnant, could it keep her out of jail? No. Unless a woman is in the last few weeks of her pregnancy, a judge normally won’t postpone her trial. About 5 percent of female prisoners arrive at jail pregnant, and most detention centers have in-house OB/GYN care. If Richie does end up pregnant in the big house, at least she’ll have the option of going to her own doctor. In California, a prisoner can visit an outside health-care provider as long as she has the funds to pay for an accompanying security detail from the sheriff’s department.

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Explainer thanks Myles Berman, a defense attorney in Los Angeles County, Lawrence Grunfeld of Reproductive Medicine Associates of New York, and Fady Sharara of the Virginia Center for Reproductive Medicine.