Evening primrose is a flowering plant that is native to North America. Its oil, which is extracted from the plant's seeds, is sold in capsule form as a supplement. Evening primrose oil is sometimes used to treat eczema, menopausal symptoms and arthritis, although the National Center for Complementary and Alternative Medicine's website states that scientific evidence does not support the use of evening primrose to treat these conditions. Evening primrose is taken toward the end of pregnancy to prepare the cervix for labor.
It's important to talk to your health care provider before taking evening primrose, especially during pregnancy.
Evening primrose oil is a natural source of prostaglandins, which are naturally occurring fatty acids similar to hormones. According to the Maternity Corner, prostaglandins work to prepare your body for labor by helping your cervix dilate.
According to Maternity Corner, pregnant women can take evening primrose oil orally starting at 34 weeks of pregnancy and vaginally beginning at 36 weeks to soften the cervix. The site recommends that pregnancy women insert two 500 milligram capsules of evening primrose vaginally once daily from 36 weeks to 38 weeks of pregnancy. After 38 weeks, you can take that same dose three to four times per day.
It's a common misconception that taking evening primrose oil can cause labor to begin; according to Pregnant Health, the effect of taking evening primrose oil while pregnant is not that significant. Evening primrose oil will only affect your cervix if your body is ready to go into labor naturally.
Seek Professional Input
It's best to consult with your medical professional before trying any home remedies to induce labor or soften your cervix, including taking evening primrose oil. According to Medline Plus, the safety of using evening primrose oil during pregnancy has not been studied.
Effectiveness of Vaginal Use
Pregnant Health says that vaginally applied evening primrose oil appears to be more effective than evening primrose oil taken orally. Inserting evening primrose oil capsules into your vagina before bed allows the oil to come into direct contact with your cervix, which makes the treatment more likely to be effective in softening your cervix. However, a review in the December 2009 "American Family Physician" states that the use of evening primrose oil during pregnancy is not proven as effective and should be avoided.