Women who take the most common form of hormone replacement therapy (HRT) experience a hearing loss of 10 to 30 percent more than those who do not.
A study of 124 women showed that age-related hearing loss is accelerated for those whose HRT includes progestin, a synthetic form of progesterone.
Women who took progestin had the hearing loss usual for women up to a decade older.
The study compared the hearing of three groups of women aged 60 to 86. 30 had taken a form of HRT that included only estrogen; 32 had taken both estrogen and progestin; and 62 had never been on HRT. Each of the women was given a variety of hearing tests.
In all the tests, women whose HRT included progestin (the most common form) had worse hearing. Tests showed that women who took progestin had problems both in the inner ear and in the portions of the brain used for hearing.
The researchers have plans to study women who have gone off HRT, to see if the hearing loss might be reversible, and they say that women on the birth control pill, which includes progesterone, should also be studied.