Anecdotes abound about “Ozempic babies”—when women wound up with unplanned pregnancies while taking both birth-control and the popular GLP-1 drugs for diabetes or weight loss.

But today marks the first official agency warning about the possibility of these drugs—specifically Mounjaro—decreasing the effectiveness of oral contraceptives.

“Women taking popular medicines for weight loss and diabetes, sometimes referred to as ‘skinny jabs,’ are being reminded to use effective contraception while taking these medicines and, in some cases, for up to two months between stopping the medicine and trying to get pregnant,” warns the U.K.’s Medicines and Healthcare products Regulatory Agency (MHRA)—akin to the U.S. Food and Drug Administration.

It goes on to specify that “Mounjaro may reduce the eff

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