No, Ina May, the cervix is not a sphincter

It must be awesome to have followers so gullible that you can make up whatever you want, no matter how idiotic, and your supporters will believe you. Ina May Gaskin, the ultimate fraud, should know. She makes it up as she goes along and homebirth advocates, among the least knowledgeable people alive on the subject of childbirth, promptly accept it.

Gaskin has made up “facts” about post dates pregnancy, maternal mortality, and animal reproduction.

Gaskin’s biggest lie? It’s hard to choose since there are so many and they are so stupid, but any top ten list of Ina May Gaskin’s biggest lies would have to include her “Sphincter Law.” Let’s let her explain it:

… I will start with the observation that the vagina and the cervix—not just the anus and the urethra—are sphincters, that is, the circular muscles surrounding the opening of organs which are called upon to empty themselves at appropriate times.

There’s just one teensy, weensy problem. Neither the vagina, nor the cervix are sphincters.

What is a sphincter? A sphincter is circular muscle that surrounds the opening of an organ, as the illustration below demonstrates.

The vagina does have some muscular fibers, but most its muscular strength is longitudinal and the cervix is not made of muscle or encircled by muscle at all. But Ina May is not worried about that since her followers don’t know any anatomy or physiology and are unlikely to check.

What is the anatomy of the vagina?

The vagina consists of an internal mucous lining and a muscular coat …

The muscular coat (tunica muscularis) consists of two layers: an external longitudinal, which is by far the stronger, and an internal circular layer…

So there is muscle in the vagina but the strongest fibers run longitudinally. In other words, it is not a sphincter.

How about the the cervix? According to Hassan et al.:

The uterine cervix is essentially a connective tissue organ. Smooth muscle accounts for less than 8% of the distal part of the cervix. Cervical competency, defined as the ability of the cervix to retain the conceptus during pregnancy, is unlikely to depend upon a traditional muscular sphincteric mechanism… It is now well-established that the normal function of the cervix during pregnancy depends upon extracellular matrix.

No, the cervix is not a sphincter, either.

The human body does have quite a few sphincter muscles including the anal sphincter and two urethral sphincters (internal and external). There are others: the upper esophageal sphincter, which opens as food passes into the stomach, the sphincter of Oddi, which controls the release of bile and pancreatic enzymes into the duodenum, and the iris, which controls the size of the pupil to regulate the amount of light entering the eye.

According to Ina May:

For anyone dealing with or organizing maternity care, probably the most important feature of sphincters to understand is that they function according to several factors:

  • Sphincters open best in conditions of privacy and intimacy
  • Sphincters open best without time limits
  • Sphincters are not under the voluntary control of their owner. They do not obey orders, such as ‘urinate now!’, ‘push!’, or ‘poop!’
  • Sphincters, however, do respond well to praise if there happens to be another person in the proximity of the sphincter’s owner. This other person might be the mother of toddler or a midwife assisting a woman giving birth
  • The opening of sphincters can be facilitated by laughter (the owner’s)
  • When a person’s sphincter is in the process of opening, it may suddenly close if that person becomes frightened, upset, embarrassed, or self-conscious. This is because high levels of adrenaline in the bloodstream do not favor (sometimes they actually prevent) the opening of the sphincters
  • The state of relaxation of the mouth and jaw is directly correlated to the ability of the cervix, the vagina, and the anus to open to full capacity. A relaxed and open mouth favours a more open vagina and cervix.

Really? Let’s test these claims.

The iris opens best in conditions of privacy and intimacy? No. The iris opens and closes in response to the amount of ambient light and privacy and intimacy have no effect.

Sphincters are not under the voluntary control of their owners? Wrong. Whether or not a sphincter is under voluntary control depends of whether it is made of smooth muscle or skeletal muscle. Both the external urethral sphincter and the anal sphincter are under voluntary control. Indeed the entire point of toilet training is to teach children to control these sphincters?

High levels of adrenaline do not favor (sometimes they actually prevent) the opening of sphincters? That’s why when people are very frightened they do not pee in their pants or defecate. Oops! That’s obviously a lie.

In fact, every one of these “rules” is nothing more than a complete fabrication, as even the most cursory knowledge of human anatomy demonstrates.

Gaskin professes surprise that no one has mentioned the Sphincter Law before.

I would argue that Sphincter Law may apply in both the first and second stages of labour. In the first stage, most of us who have been midwives for several years have noticed that, once in labour, a woman’s cervix will occasionally close. I described the first such case (Gaskin, 1978), but I have found no other documentation in the 20th and 21st century medical literature of this rather common phenomenon…

That’s hardly surprising, Ina May, since you made the whole thing up.

There is a saying in science that extraordinary claims require extraordinary proof. In the world of homebirth, extraordinary claims require no proof at all, just a self-proclaimed “midwife” willing to lie and a bunch of ignorant followers willing to believe.