Sex in pregnancy: A primer

Potential, although uncommon, risks of sex in pregnancy include premature labour, pelvic inflammatory disease, hemorrhage in placenta previa (when the placenta covers part of the cervix) and blood clots.

While restriction of intercourse is recommended for women at risk of premature labour, the evidence is contradictory and limited. In low-risk women, frequent intercourse was associated with an increased risk of premature labour only in women with lower genital tract infections. In higher risk women -- carrying more than one baby, with cervical incompetence or a history of early labour -- there is limited evidence to guide recommendations.

"In populations at increased risk for preterm labour, there is no evidence to suggest a clear benefit from restricted sexual activity; however, this is a simple intervention that causes no harm and may be a reasonable recommendation until better evidence emerges," writes Dr. Clair Jones, Department of Obstetrics, Mount Sinai Hospital and University of Toronto with coauthors.

In rare cases, some types of sexual activity that push air into the vagina may result in a uterine blood clot that is usually fatal.

"Sex in pregnancy is normal," write the authors. "There are very few proven contraindications and risks to intercourse in low-risk pregnancies, and therefore these patients should be reassured. In pregnancies complicated by placenta previa or an increased risk of preterm labour, the evidence to support abstinence is lacking, but it is a reasonable benign recommendation given the theoretical catastrophic consequences."

They state that there is no evidence to the theory that sex at term can induce labour but that there are no known negative outcomes for women with low-risk pregnancies.

The authors conclude comfort level and readiness to engage in sexual activity should guide both sex during pregnancy as well as in the postpartum period.