Smoking may contribute to pelvic pain in pregnancy

NEW YORK (Reuters Health) - A lower risk of pelvic pain could be yet one more reason for women to quit smoking before becoming pregnant, a new study suggests.

Danish researchers found that among 5,000 women interviewed during and soon after pregnancy, those who smoked during pregnancy were 20 percent more likely to have pregnancy-related pelvic pain than non-smokers.

A similar risk was seen among women who had given up smoking during the first trimester, according to findings published in the obstetrics journal BJOG.

Pelvic pain is believed to be a common problem in pregnancy, with recent studies finding that anywhere from 14 percent to 33 percent of women develop it -- most often in the second half of pregnancy.

The pain can make routine activities, like walking, getting up from a chair or even turning over in bed, difficult. So it is important to reduce the risk of developing the pain, if possible.

The current findings show an association between smoking and pelvic pain, but do not prove cause-and-effect. Still, there are many reasons for women to quit smoking, particularly if they are planning a pregnancy.

So a reduction in the risk of pelvic pain can be viewed as a potential added benefit, according to lead researcher Karin Biering, of Herning Regional Hospital in Denmark.

Smoking during pregnancy is linked to increased risks of miscarriage, low birth weight and other pregnancy complications. So the most important reason for women to quit before pregnancy is for the health of their child, Biering told Reuters Health in an email.

"The finding of our study just adds another possible consequence of smoking," she said.

The results are based on data from a subgroup of women included in a national study of more than 100,000 pregnancies between 1996 and 2002. Women in that study were interviewed during pregnancy and six months after giving birth.

Biering's team compared 2,300 women who reported having pelvic pain during or shortly after pregnancy with nearly 2,700 who did not report the problem. Pelvic pain was defined as pain that was at least significant enough to affect a woman's ability to walk.

Overall, the study found, smokers -- including those who quit in early pregnancy -- had an elevated risk of pelvic pain, even taking into account a number of other factors, such as age, obesity, the women's self-rated general health and whether they had a physically strenuous job.

It is not clear why smoking might contribute to pelvic pain during pregnancy. In theory, it may be related to reduced blood flow to the pelvic tissue, according to Biering.

Even if smoking is a risk factor for pregnancy-related pelvic pain, being a non-smoker is no guarantee that a woman will not develop the problem. Among women with mild pelvic pain in the current study, 73 percent were non-smokers; of those with severe pain -- pain bad enough to interfere with several daily activities -- 69 percent were non- smokers.

Pelvic pain is a "complex" condition, Biering noted, and there are probably numerous factors involved in pregnant women's risk.

SOURCE: http://link.reuters.com/gyj82m BJOG, online May 26, 2010.