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Inducing labour with Castor oil : is it safe?

Castor oil induction has bad press in the UK. Negative stories abound, claiming severe negative effects on mother and baby. For years, I too believed this to be true. I took it for granted that it was dangerous.

A couple of years ago a doula told me that several of her clients had successfully induced their labour with it, and that the stories didn’t match their experience. She also said that, faced with the prospect of a long induction in an antenatal ward, some women felt that it was a lesser evil. This conversation spurred me to look for the research. I was very surprised to find that it was actually quite safe, and that the stories didn’t match what the published research said.

Birthworkers often talk about strongly held beliefs within maternity care, that turn out to be myths. You know, the kind of belief that everybody seems to have, without question, that gets perpetuated through stories, yet when you analyse the research you find that there is very little evidence to back it up (the placenta “failing” at the end of pregnancy being one of the most common ones). After reading the research on induction with Castor oil, I was embarrassed to admit that I’d fallen prey to this myth believing myself.

I cannot help but wonder how Castor oil came to have such bad press in the UK. For some reason it has fallen out of fashion here (Midwife Becky Reed told me that it used to be used in the UK in the past), and yet it is still more commonly used in the USA. A survey of 500 US midwifes in 1999 showed that it was the most commonly used natural substance used to induce labour.  American Midwife Ina May Gaskin mentions it in her Guide to Childbirth. When Ina May came to a the Doula UK conference in 2017, doula Sue Boughton asked her what she thought of it and she said that it was perfectly safe and that they used it all the time.

This is what Ina May says in her book, Ina May’s guide to Childbirth:

“Indigenous peoples all over the globe have used castor oil to induce labor for centuries. Taken orally, castor oil acts as a laxative, and the stimulation of the digestive tract often starts labor at term. No one knows why castor oil works to start labor. When there is little or no money to be made as a result of research, generally little or no research is done. Nobody has figured out how to make an appreciable amount of money from castor oil, so this subject has received virtually no research attention. Nevertheless, castor oil seems to be quite safe. Nearly nine percent of nearly eleven thousand pregnant women in a large birth center study used it to start labor, with no adverse outcomes. At The Farm Midwifery Center, we recommend beginning a castor-oil induction at breakfast after a full night of sleep. One tablespoon of castor oil is added to scrambled eggs or is mixed with fruit juice to make it more palatable for the women. If necessary, she takes one more tablespoon one hour after ingesting the first.”

I want to share what the research says, to help you decide whether you think that castor oil induction is a good idea or not, and also so that there is an up to date review of the evidence to signpost women to, if they feel that it is an option that they would like to explore.

Before I do this I need to give an important disclaimer: I believe that our culture’s obsession with inducing labour as soon as a certain date has reached  is not only unhealthy, it is also not based on solid scientific evidence. I wrote about this before in this blog. Therefore I want to be clear that I haven’t written this blog to encourage women to induce labour with castor oil. It is designed to provide a review of the evidence so that people can make truly informed decisions.

what is Castor oil?

Castor oil is an oil extracted from castor beans, which are produced by the castor plant, Ricinus communis. It has laxative properties. (It is often used to empty the bowel in a medical setting prior to examinations )

How does Castor oil work?

The way Castor oil stimulates labour was only elucidated in 2012. Contrary to popular belief, castor oil doesn’t only work by only stimulating the gut (though this might play a role in the process as well). After being ingested, castor oil is broken down in the intestine, releasing ricinoleic acid, the main fatty acid in castor oil. Ricinoleic acid attaches directly onto receptors which are present in both the bowel and the uterus. As well as stimulating contractions of the smooth muscles in the bowel, research has shown that it causes uterus tissue to contract, and that in mice that lack its target receptor (prostaglandin receptor EP3) it does not produces uterine contractions.

How is it taken?

Castor oil is taken orally. Although Ina May Gaskin suggest a tablespoon or two (A tablespoon is about 15ml), most of the research studies used a dose of about 60 millilitres (so 4 tablespoons). It is usually suggested to mix it with fruit juice to make it more palatable. Interestingly, in one paper the authors used sunflower oil as a placebo and said that women couldn’t taste the difference between Castor oil and sunflower oil once it had been mixed in orange juice. One publication refers to a cocktail or smoothie as follow:

  • 2 ounces castor oil
  • 1 cup champagne
  • 1 cup apricot nectar
  • 4 tablespoons of almond butter.

How effective is it?

There is a Cochrane review of the literature from 2013, which includes 3 studies: . The three trials included in the review contain small numbers of women. All three studies used single doses of castor oil. The results from these studies should be interpreted with caution due to the risk of bias introduced due to poor methodological quality. Further research is needed to attempt to quantify the efficacy of castor oil as an induction agent.

  • In one study of 47 women, there was a significant increase in labour initiation in the castor oil group compared with the control group (54.2% compared with 4.3%)
  • In one study of 100 women , 52 women received castor oil and 48 no treatment. Following administration of castor oil, 30 of 52 women (57.7%) began active labour compared to 2 of 48 (4.2%) receiving no treatment. When castor oil was successful, 83.3% of the women had a vaginal birth.
  • In one study of 80 women (37 in the treatment group and 43 to the control group) the odds of entering the active phase of labour within 12 hours of administration was 3 times higher among women receiving castor oil compared to women receiving a placebo.

Two other papers not included in the review, were published in 2018. In one of these papers, 323 women (who birthed in a birth centre) used castor oil to induce labour showed that 81% of the women gave birth vaginally, and the authors stated that this was significantly higher than the national average. They concluded that ” Our results show women who consumed a castor oil cocktail to induce labor experienced adverse fetal and maternal outcomes at very low rates. Further research, including a clinical trial, should be conducted to test the safety and efficacy of castor oil as a natural alternative to labor induction.”

In the other paper, 82 women were divided in 2 groups of 38 and 44 , and respectively received castor oil and a placebo (sunflower oil). Of the women who received castor oil, 42.1% entered labour within 24 h, 50.0% within 36 h and 52.6% within 48 h compared with 34.9%, 37.2% and 39.5% in the control group. The authors also found that castor oil was effective in stimulating labour in multiparous women (women who had already had at least one baby) but not in first time mothers. No differences in rate of obstetric complications or adverse neonatal outcomes were noted.

I tried to find some research to compare the effectiveness of Castor oil versus the most common form of drug used to start the induction process in the UK : Prostaglandins, which are usually administered vaginally. This proved complex because the Cochrane review cites many different studies, all with different populations and different outcomes. For example one study with women of mixed parity (first time mothers and multiple pregnancies mothers mixed together), found that, in a study of 343 women with a favourable cervix (this means their cervix was already in a condition close to labour) and a 3mg dose of prostaglandins, found that 12% of women were still pregnant after 24h versus 100% of women who didn’t have the induction. In a smaller study of 39 first time mothers with an unfavourable cervix and a smaller dose of prostaglandins (2mg) compared with a placebo, 79% of the prostaglandin group and 90% of the placebo group were still pregnant after 24 hours. When combining the data the reviewers could not reach statistical significance. The reviewers conclude after looking at all the studies that ” Overall therefore, although not certain, it is likely that vaginal prostaglandin E2 compared with placebo or no treatment reduces the likelihood of vaginal delivery not being achieved within 24 hours.”

This gave me pause for thought, because on one hand, our culture can be quick to dismiss natural remedies as quackery and non evidence based. Yet I was surprised to discover that the research doesn’t show prostaglandin pessaries as being a very effective drug when it comes to labour induction, but because this is part of the normal maternity care, this doesn’t get questioned. You might be surprised to hear that only 9-12% of the royal college of obstetrician guidelines are based on high quality evidence. I also couldn’t help but wonder how many of the women who get offered an induction of labour get given the statistics about how successful the process is likely to be.

What are the side effects of Castor oil?

The most common side effects are diarrhoea (which is to be expected as Castor oil is a laxative) and nausea.

  • In the study of 47 women, 45.8% experienced nausea versus 0% in the control group.
  • In the study of 100 women , 100% of women who took the castor oil reported nausea compared to 0% of the women in the control group.
  • Contrary to the high level of nausea and diarrhoea described in the studies above, in the first 2018 study, out of 323 women, only 7 (2.2%) experienced nausea. The authors concluded that ” In the current study, the low incidence of maternal and fetal adverse effects suggest castor oil may be a safe and agreeable way to stimulate labor and avoid unnecessary caesarean birth. Although previous studies cited adverse maternal effects (e.g. nausea, vomiting, diarrhea) as a barrier to castor oil use, participants in this study who received the castor oil cocktail reported a low rate of these effects. In fact, less than 4% of the sample experienced nausea, vomiting, or extreme diarrhea.”
  • In the other 2018 study, 32 out of 81 women (40%) experienced an increase in bowel movement, 4–6 h after ingestion of the oil (42.1% in the intervention group and 37.2% in the control group (who received sunflower oil). The authors did not observe any serious adverse events, and concluded that “Castor oil is an effective substance for induction of labor, in post-date multiparous women in an outpatient setting“.

Castor oil does not appear to cause severe side effects on the mother or baby. The Cochrane review authors concluded that “There was no evidence of a difference between castor oil and placebo/no treatment for the rate of instrumental delivery, meconium‐stained liquor, or Apgar score less than seven at five minutes.

What else matters when it comes to decision making?

Beside the science showing that Castor oil appears to be pretty safe and effective, there are other aspects to consider. As I explain in this blog , induction of labour is an intervention that has many pros and cons, and you have to weigh the balance of pros and cons for you as a unique individual, with your own unique circumstances. And it is also important to remember that Castor oil IS a form of induction, regardless of the fact that it is a natural substance.

What are the possible advantages of using castor oil to induce labour?

  • It can allow women to remain in control of the start of the birth process, and to choose where they give birth. When labour is induced in a hospital ward, you are committed to a process, which restricts your birth options. In most hospitals, being induced means the only option is to labour in the antenatal ward (though some hospital offer outpatient induction), then give birth in the labour ward. If you induce labour at home then you remain in control of the choice of place of birth, whether at home, in a birth centre, or in a labour ward.

The authors of the first 2018 paper stated that ” By stimulating labor and decreasing the necessity for intervention via cesarean section, castor oil as a method of labor induction may enable women to adhere to their birth plans (e.g., at a birth center, vaginally, etc.), benefiting from these positive outcomes

  • It can allow women to remain in their own environment, with their support partners of choice. Induction of labour can take days, and it is sometimes stopped or delayed half way through if the induction or labour ward becomes full. Because of this, in the recent past I  saw many women undergoing induction lasting up to 5 days. Now in 2020, the new visitor restrictions due to Covid19 mean that partners aren’t allowed in the hospital until women are in established labour. For the mother this may mean days of early labour without any support from anyone she knows and trusts, as well as having no one to help advocate for her.

I have supported such births recently and they felt very frustrating for the mother, her partner and myself. I provided remote support over the phone, but in my experience the induction felt more upsetting than usual with the lack of face to face support from the partner and myself. I know this frustration is shared by others, and a recent publication has highlighted how women’s rights in childbirths are not being respected since the beginning of pandemic:

“The position of the rights of women in childbirth is in this context a precarious one. Stories have emerged in mainstream media – supported by personal accounts received by global and European birthrights organizations – of women having their labor induced, being forced to have cesarean sections, giving birth alone, and being separated from their babies immediately after birth.”

  • Impact on support after the birth

Women whose labour is induced are more likely to end up with medical interventions such as caesarean or an instrumental birth, which may mean a longer stay in the hospital post birth. With Covid restrictions in place, partners are only allowed in postnatal wards for a 1 to 2h visit daily. If a new mother is recovering from a caesarean, or if she is very tired after a long labour and birth, this simply isn’t enough support for a her to get some rest and recover after the birth. Nobody is there to comfort her, or to hold the baby whilst she sleeps. I have listened to many harrowing such stories from new mothers to know that this is a very difficult situation to be in.

What are the possible disadvantages of using castor oil ?

  • The side effects mentioned above might not be acceptable to some women or their partner.
  • Some women may feel safer being induced in a medical setting.

In conclusion:

Using Castor oil to induce labour can cause side effects such as diarrhoea and nausea but it appears to safe for mother and baby. It is also a fairly effective, especially when women have already had one or more babies. Some families may perceive that it is important for them to retain control over the induction process, and may decide that having the diarrhoea and nausea might be an acceptable side effect, compared to the reality of being being induced in a hospital setting.


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