Danish Study Links Oral Menopause Hormones to Clot Risk

A large Danish study found that women using oral menopause hormone therapy had higher rates of blood clots in the legs or lungs than women not using the treatment, while patches, gels and sprays were not generally associated with increased clot, stroke or heart-attack rates. The observational findings, published in The BMJ, show associations and do not establish that hormone therapy caused the events. The researchers examined Danish health and prescription records for women aged 50 to 69 from 2003 to 2021. They identified 9,807 women who experienced a first venous blood clot, 18,460 who had an ischemic stroke and 11,974 who had a heart attack, then compared them with women matched by birth year who had not experienced the respective conditions. Oral estrogen, taken alone or with a progestin, was associated with higher venous clot risk across the doses and treatment durations examined. Researchers estimated about one additional clot for every 1,055 women treated orally for a year. The increase was small in absolute terms, and most women using oral therapy in the study did not experience a clot. Stroke and heart-attack risk signals followed a narrower pattern.