Evening primrose oil and labour: effective for inducing labour?

Evening primrose oil is a rich source of essential omega-6 fatty acids. It contains gamma-linolenic acid, which is considered the active ingredient in evening primrose oil. It is a precursor of prostaglandins E1 and E2, which contribute to cervical ripening and prepare it 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 induction of labour naturally. So, is it really one of of the best pregnancy food supplements ?

As a reminder: evening primrose oil is not recommended during pregnancy. Do not take it before the last month, and only on medical advice. 

Study data on the effectiveness of consuming evening primrose oil to induce labour are mixed. When we ask ourselves how to give birth more quickly, evening primrose oil could be one of the options worth considering. 

Some studies show that it is effective

Several clinical trials report encouraging results. A 2006 study observed a significant improvement in Bishop score (an indicator of cervical ripening) in women who took evening primrose oil, as well as a reduction in cervical length and a higher rate of vaginal delivery, 70% versus 51% in the placebo group [2].

A 2022 study also found an improvement in Bishop score [3]. A triple-blind 2023 trial confirmed an improvement in Bishop score as well as a reduction in the time between the start of induction and delivery [4].

Finally, a 2023 meta-analysis, bringing together five studies and 652 participants, concluded that there was a significant improvement in Bishop score among women supplemented with evening primrose oil [5].

Studies show that there is no effect

Other research qualifies these conclusions. A 1999 study found no significant difference in the duration of pregnancy, although a slight variation in birth weight and duration of labour was observed [6]. 

For its part, a 2018 randomised trial found no significant difference between the supplemented group and the control group, whether in terms of gestational age at delivery, duration of labour or Apgar scores [7].

A 2021 meta-analysis, covering four studies and 680 women, points in the same direction: it found no significant effect of evening primrose oil on Bishop score or cervical ripening [8].

Studies show that it has no side effects

One point on which the studies do agree, however, is safety. None of the research conducted reports any notable complication linked to taking evening primrose oil at the end of pregnancy. Fetal biophysical profiles and fetal wellbeing tests remained normal [2], and Apgar scores, birth weight and meconium excretion showed no concerning difference between the supplemented and control groups [7][4][5]. The 2021 meta-analysis also confirms the absence of complications associated with its consumption [8].

So, is it worth it?

Looking at all the available literature, more studies report a positive effect of evening primrose oil on cervical ripening and the course of labour than studies showing no effect. The results are therefore not unanimous, but the trend leans towards a possible benefit.

Above all, all research conducted to date agrees on one essential point: taking it at the end of pregnancy has shown no adverse effects for the mother or baby. Under these conditions, and always in agreement with your midwife or doctor, it may be relevant to try it from the 37th week of pregnancy, at around 1500 mg per day, the dose most frequently studied. Since the risk is low and the potential benefit is real, there is no harm in trying.

Researchers published a trial to assess the effects of vaginal evening primrose oil on cervical ripening in women pregnant for the first time at term [9]. 43 women received a daily dose of 1000 milligrams of evening primrose oil in a soft vaginal capsule from the 38th week of pregnancy until birth, and 43 others received a placebo. They observed: 

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

A shorter average duration of early labour (4 to 5 hours versus 8 to 9 hours). 

MFewer caesarean sections (21% versus 47%).

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

No side effects were reported.

Another trial assessed the effects of vaginal evening primrose oil on cervical ripening [10]. Women were randomly given either a single vaginal capsule containing 1000 milligrams of evening primrose oil or a placebo vaginal capsule. The researchers found that the the duration of the initial phase of labour and the average Bishop score were both significantly improved among those who were given evening primrose oil during induction.

Evening primrose oil is traditionally used to promote a natural birth. Although studies do not allow us to state with certainty that evening primrose oil facilitates birth, most results are in its favour and its safety is well established: in other words, it has its place in your end-of-pregnancy routine, with no risk in trying it. 

Consumption of raspberry leaf herbal tea could also be effective. 

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