Women who used estrogen for at least five years are more likely to develop bladder control problems later, a study reports in the journal Menopause.

Researchers survedy 167 postmenopausal women in the early 1990s and again in 2004. Women who reported using estrogen for five years or longer were three to four times more likely to report new cases of urinary incontinence in the latter survey, the study found. Thirty-one of the survey respondents said the bladder control problems made daily tasks such as shopping, exercise, and visiting friends difficult.

Dr. Gina Northington, an author of the study who specializes in urogynecology at Emory University in Atlanta, points out a few weaknesses with the research.

"We only asked women if they took hormones containing estrogen," she said.
"We didn't measure the level of estrogen and we didn't ask about progesterone."

Also, urinary problems increase with age, points out Dr. Leslie Rickey a urogynecologist who specializes in bladder problems at the University of Maryland Medical Center and is not associated with the study. "We're not sure if [the increase in incontinence is] due to the aging process or estrogen levels or the combination of the two."

Earlier research has shown that up to half of all women over the age of 44 have reported incontinence at least once.

Estrogen is sometimes used to reduce menopausal symptoms such as hot flashes and vaginal dryness.