Despite some concerns, the pelvic-muscle exercises many women do during pregnancy do not seem to raise the likelihood of complications during labor and delivery, a new study finds.

Prenatal exercises for the muscles of the pelvic floor, also known as Kegel exercises, have long been advocated for preventing incontinence during and after pregnancy.

However, some doctors have expressed concern that the muscle training may make the pelvic floor too strong and less elastic, making labor and delivery more difficult.

To look into this, Norwegian researchers surveyed nearly 19,000 women who gave birth between 2000 and 2005. The investigators report in the journal Obstetrics & Gynecology that women who frequently performed Kegel exercises were no more likely to suffer tears during delivery, or to need an unplanned Cesarean section or instrument-assisted delivery.

It's important for women to know that prenatal pelvic-floor exercises can lower the risk of urinary incontinence, lead researcher Dr. Kari Bo, of the Norwegian School of Sports Sciences in Oslo, told Reuters Health.

These latest findings, she said, should reassure them that the exercises also do nothing to interfere with childbirth.

Of the women in the study, 28 percent started performing Kegel exercises at least three times per week by the 30th week of pregnancy. Another 43 percent did them less than once a week or not at all.

Overall, the study found, roughly 7 percent of women who infrequently or never performed Kegel exercises suffered severe tearing during childbirth, compared with 6 percent of those who frequently performed the exercises.

Rates of delivery requiring forceps or a vacuum were 16 percent and 15 percent, respectively, while unplanned C-section rates were 9.5 percent and 7.5 percent.

Women should feel reassured that pelvic-floor training will not negatively affect childbirth, even though many health professionals seem to believe this is a possibility, according to Bo.

"That is a myth," she said.