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Castor Oil and Meconium

Meconium during labour--self-medication and other associations.
Mitri F, Hofmeyr GJ, van Gelderen
S Afr Med J 1987 Apr 4;71(7):431-3
[This study doesn't account for the likely association between taking castor oil and being postdates, which is known to be associated with meconium.]

The problem I've heard of with castor oil (besides making you miserable and not always working) is that it can cause the baby to pass meconium in the uterus because the castor oil causes a relaxation of sphincters. 

Castor oil, although used a great deal in the past, is no longer advised as its effects on the baby can be similar to its effects on mom, i.e., it stimulates movement of the bowels, which can lead in babies to meconium in the amniotic fluid. If you think bowel stimulation will help, try an enema instead. 

I've also heard that it is believed to be associated with a higher risk of the baby passing meconium before or during the birth. 

I have never associated castor oil with meconium, and I don't understand the possible relationship that some people think it has...can anyone explain? When I worked in TX, the law mandated anyone over 42 weeks had to deliver in a hospital, so the birth center castor oiled a LOT...NEVER saw an increase in mec with those ladies.

It doesn't pass into the baby's blood stream, so should not cause meconium.

I think when we do see meconium it may be because the mom is overdue in the first place, and have nothing to do with the castor oil. Does that make sense??? Especially since we wouldn't advise castor oil until postdates???

Makes more sense than anything else. Castor oil works by irritating the digestive system which irritates the uterus, and by delivering prostaglandins to the woman's body, presumably through the digestive tract. There is no way this would pass through to the baby's digestive tract.

I guess I have to put my 2 cents in on this. I have used castor oil lots and work with a group that will take it as matter of course, without my knowledge. I have never seen meconium with its use. I have done over 200 births with these people and have never had meconium at all. That is pretty amazing, isn't it, but true. 

We use castor oil in our practice for ladies who already have a ripe cervix, and have had excellent luck with it causing labor; no evidence of increased mec.

I am very interested in what are the physiological mechanisms that could possibly cause the necessary substances to pass to the baby and cause her to pass meconium intrauterinely. Not only have I ever read any evidence to this effect, I have never, before this forum, heard of the connection. 

This discussion of the use of castor oil made me delve for a dimly remembered Midirs article which examined research on the subject (Dec. 1994- if anyone else wants a read) to try and clarify these meconium muddied waters...

It discusses a terrible (for the participants)sounding study in which women between 38 and 41 weeks were given various cocktails of hot baths, castor oil and enemas and uterine activity was monitored. Castor oil increased 'activity' by 186% apparently but it wasn't clear from the study whether this meant labour (I would have thought all the running to and from the lavatory would have made as much of a difference) or what the cervical condition was when the castor oil was used.

Another retrospective study compared two groups of low risk women with pre labour rupture of membranes. One lot got 50mls of oil four hours after admission (does this mean four hours after rupture?- sounds pretty arbitrary). None of the group had meconium stained liquor following ingestion, but they all developed diarrhea. Significantly more laboured spontaneously in the oily group than the non-oiled.

Finally one prospective study looked at 498 'high risk' women and found a higher incidence of meconium stained liquor in those who had self administered castor oil than those who had used enemas or laxatives.

The authors of the review conclude:

Castor oil does appear to stimulate uterine activity although the mechanism remains unclear. No healthcare professional would consider administering an unknown quantity of prostaglandins or not monitoring mother or fetus after attempting to stimulate labour. Yet this is.. what occurs when women are advised to take castor oil. Uncontrolled uterine activity can occur... Hyperstimulation can lead to fetal distress and the passage of meconium which increases the risk of intervention

Didn't the article first appear in "Modern Midwife"? Anyway, I've read the article and all it says to me is to examine the quality of research carefully before coming to conclusions.

The study which claimed a correlation between mec and castor oil was conducted by interviewing women in labour about self-medication before rupturing their membranes. Interviews are notoriously fraught with problems, one of them being that people tend to tell interviewers what they think they want to hear (or not hear). Also the numbers in the study were really not all that large, nor do we know anything about quantities etc. etc. etc. Finally, correlation or association does not mean cause.

No good research has, to date, been done, and it's something that I would love to see done (actually wrote a proposal for the study for a research methods course I did in midwifery school). It certainly used to be a tried and true method of induction in the pre-oxytocin days when my mom was a labour and delivery nurse. She took it to have me and I took it to avoid an induction for my second (worked too, and there was no mec).

We use it a fair amount in the practice I am in. If taken properly, it doesn't cause the "horrible" symptoms that Margie describes. We have women take 60 ml, mixed with 60 ml OJ and a tsp of baking soda. They mix the stuff over the sink (because it foams once the baking soda goes in, which emulsifies the oil), and slurp it down fast with a big-bore straw, bypassing the taste buds. They then nibble on a cracker or dry toast, which seems to help settle any castor oil "burps" afterwards.

Usually, we notice that women will start expelling the CO etc. about 1 to 2 hours later, and start contracting a few hours after that. Although some find the diarrhea somewhat unpleasant, it's usually short-lived.

It doesn't always work, and I agree that the cervix has to be favourable for it to work. As well, if a woman already has significant haemorrhoids, I don't recommend that she try this, as it will aggravate them (as any case of the runs would). Observationally, we do not notice anymore mec in the castor oil moms than in the spontaneously labouring ones (even the postdates ones).

Inhibition of water absorption by ricinoleic acid. Evidence against hormonal mediation of the effect.
Gadacz TR, Gaginella TS, Phillips SF
Am J Dig Dis 1976 Oct;21(10):859-62

This study implies that the effect of castor oil in creating diarrhea is a relatively localized effect, and that it reduces the absorption of fluid from the intestines.  It's hard to imagine how the mom's ingesting castor oil would cause the castor oil to show up inside the baby's intestines.  And, if it did, the baby's intestines are filled with mec, which doesn't have a lot of fluid to be absorbed or not.