An expecting mom in her 37th week of pregnancy told me that her midwife recommended that she take evening primrose oil to bring on labor slowly, but surely. The mom asked me if there would be any side effects for her daughter-to-be.
Evening primrose oil is a natural, mild anti-inflammatory agent that has been widely used to hasten cervical ripening and shorten labor. Researchers at the Holistic Women’s HealthCare Birth Center in Wilmington, Delaware set out to test whether it really works. Their findings were published in the Journal of Nurse-Midwifery in May/June 1999. They found that evening primrose oil does nothing to shorten gestation or improve labor. Instead they found an increase of premature rupture of membranes (and increased infection risk), oxytocin augmentation, arrest of descent, and vacuum extraction. Evening primrose oil does have other valid uses, but I do not recommend it while pregnant.
I’m glad the mom asked! Just because something is natural, it doesn’t mean that it is safe or effective.