Evening primrose oil and labour: effective for inducing labour?

Evening primrose oil is a rich source of omega-6 essential fatty acids. It contains gamma-linolenic acid, which is considered the active compound in evening primrose oil. It is a precursor to prostaglandins E1 and E2, which contribute to cervical ripening and prepare the cervix for labour [1]. 

Researchers therefore hypothesised that the impact of evening primrose oil on the prostate glands could be beneficial for cervical ripening and the labour induction naturally. So, does it truly belong of the best pregnancy food supplements ?

The data from studies on the effectiveness of evening primrose oil for inducing labour are conflicting. When wondering how to give birth more quickly, again evening primrose oil may not be the best option. A combined study of 6 articles also showed that oral intake of evening primrose oil was not effective for inducing labour [2].

An older study from 1999 examined the effect of oral evening primrose oil in 54 women and compared it with an equivalent group who had not taken it [5]. The prescribed dose of evening primrose oil was 500 mg orally three times a day for one week from the 37th week of pregnancy, then 500 mg orally once a day until the onset of labour. They noted that taking evening primrose oil did not shorten the duration of pregnancy or the overall duration of labour. 

Beyond the lack of efficacy, they observed that this was associated with a increased incidence of prolonged rupture of membranes, increased oxytocin use, arrest of descent, and vacuum extraction.

What about vaginal evening primrose oil for inducing labour?

Researchers published a trial to evaluate the effects of vaginal evening primrose oil on cervical ripening in first-time pregnant women at term [6]. 43 women received a daily dose of 1,000 milligrams of evening primrose oil in a soft vaginal capsule from the 38th week of pregnancy until delivery, and 43 others received a placebo. They observed: 

A better Bishop score for those who had received evening primrose oil (7.8 with evening primrose oil compared with 4.5 with the placebo). 

A shorter average early labour duration (4 to 5 hours compared with 8 to 9 hours). 

Mfewer caesarean sections (21% compared with 47%).

Less use of synthetic oxytocin to induce labour (29% compared with 62%). 

No side effects were reported.

Another trial evaluated the effects of vaginal evening primrose oil on cervical ripening [7]. Women were randomly allocated either a single vaginal capsule containing 1,000 milligrams of evening primrose oil or a placebo vaginal capsule. The researchers found that the duration of the initial phase of labour and the mean Bishop score were both significantly improved in those who had been given evening primrose oil during induction. 

Evening primrose oil is traditionally used to encourage a natural birth. However, studies on its oral consumption show controversial results regarding its efficacy. Overall, it does not appear to trigger labour. Only one study shows possible risks, but that study dates from 1999. Beyond the lack of efficacy, it cannot be stated with certainty, given current data, that this is without risk.  

However, it appears that vaginal administration of evening primrose oil could potentially help trigger labour, and safely so according to current studies. 

The consumption of raspberry leaf tea does appear to be effective. 

Acupuncture can also be very useful as a complementary approach. To find out more about this practice, read our article: pregnancy acupuncture.