Researchers at UCSF and UC Davis discovered a hormone, named Maternal Brain Hormone (CCN3), which maintains bone strength in breastfeeding women despite calcium loss. This hormone could potentially treat osteoporosis and aid in healing fractures across different demographics. The study emphasizes the importance of including female subjects in biomedical research to uncover gender-specific biological processes.

Researchers from UCSF and UC Davis have resolved a longstanding mystery about how breastfeeding women maintain strong bones despite losing calcium to milk production. A newly discovered hormone that keeps the bones of breastfeeding women strong could also help bone fractures heal and treat osteoporosis in the broader population. Researchers at UC San Francisco and UC Davis showed that in mice, the hormone known as Maternal Brain Hormone (CCN3) increases bone density and strength.

Their results, published in Nature , solve a long-standing puzzle about how women’s bones remain relatively robust during breastfeeding, even as calcium is stripped from bones to support milk production. “One of the remarkable things about these findings is that if we hadn’t been studying female mice, which unfortunately is the norm in biomedical research, then we could have completely missed out on this finding,” said Holly Ingraham, PhD, the senior author of the new paper and a professor cellular molecular pharmacology at UCSF. “It underscores just how important it is to look at bot.