Doctors trying to figure out what midwives have known for millenia

I save a lot of stories and websites on my computer bookmarks or “favorites,” and just the other day, I came across this link to an article in a British newspaper entitled, “Cramp blamed for Caesarean boom.” It says that doctors have found higher-than-normal levels of lactic acid in the wombs of women who have had a C-section. Interesting. In doing some more research on lactic acid, I’ve discovered that there are conflicting theories. The old idea (which this newspaper and/or doctor hold to) is that lactic acid is a waste by-product of muscles working too hard with not enough oxygen–this stemming from experiments a scientist did about a century ago and just handed down as unassailable truth. Newer theories and newer research does not back up the idea that lactic acid causes muscle cramps, although it is noted that high levels of lactic acid are indicative of muscle cramps and fatigue. But whether it’s a “cause and effect” question, or that excess lactic acid is simply a marker of muscle fatigue is unknown. More research is needed, but what is known is that intense activity causes lactic acid to accumulate.

In the article, it mentioned that lactic acid build-up is well-known among athletes, so I dug further and found this article on Muscle Cramps/Spasms: Nutritional Causes, Prevention, and Therapies. Again, very interesting. Although it deals primarily with athletes, and training for things like long-distance running and biking, as well as weight-lifting, it made me wonder if some of the things could apply to labor. Since labor typically takes many hours, perhaps even more than 24 hours in some cases (I’ve even heard of labors taking several days), it would definitely qualify as an athletic event. This article makes me wonder how much of the pain of labor, and the length of labor, and labor dysfunction and dystocia, can actually be traced to nutritional deficiency (since it implicates low calcium or vitamin E intake in some causes of cramps and lactic acid build-up).

This article was also interesting in that it says that lactic acid is made by breaking down glucose, and is used as fuel by the muscles; and when athletes train in brief intense spurts before their competitions, they increase their ability to burn lactic acid as fuel. Braxton Hicks contractions, anyone?

And then there is this article, which has the following quote:

Lactic acid does not cause that dreaded burning sensation during intense exercise. Lactic acid is formed from the breakdown of glucose, our body’s main source of carbohydrate. When made, it’s split into a lactate ion (lactate) and a hydrogen ion. The hydrogen ion is the bad guy–the acid in lactic acid that interferes with electrical signals in nerve and muscle tissue. When the rate of lactic acid entry into the blood exceeds our ability to control it effectively, then those pesky hydrogen ions begin to lower the pH of muscle. This invariably interferes with how the muscles contract and thus our ability to perform. [emphasis added]

So this makes me think that glucose is burned as the first muscle fuel, and lactic acid is secondary. The more efficient your muscles are at burning lactic acid the better, because if too much lactic acid builds up then it lowers the pH of muscle, and causes problems with contractions. Or perhaps this hypothesis is wrong, and that high levels of lactic acid simply indicate that your muscles can’t use it quickly enough, so it’s running out of fuel. Your uterus is a muscle, and it needs to be able to efficiently contract in order for your cervix to dilate, and then to push your baby out.

This leads me to an article in the current Runner’s World magazine (March 2008), about world-record holder Paula Radcliffe. This article talks about her pregnancy, baby and birth as part of a larger discussion of the British runner’s life and running career. As a birth junkie, the birth part is what I’m most interested in. She was induced because she was more than a week overdueno reason other than she went past a magic date on a calendar. Although she ended up having a vaginal birth, inductions are much more likely to fail (and then necessitate a C-section) in first-time moms. She did, however, have an extremely long and painful labor, which is also pretty typical of inducing a first-time mom–in her case, 24 hours of Pitocin-induced contractions, which most women will say is harder than normal labor. Here is a quote from the magazine article:

There were the 14 hours sitting immobile and cross-legged, under orders not to get up; there was the raging thirst she wasn’t permitted to quench because they told her she might eventually need a cesarean and therefore could have nil by mouth, as doctors say. (‘They said, “Imagine that this is a marathon and so you can’t have anything to drink!” I said, “Actually, in a marathon you can start drinking at five kilometers.” They said, “You can wet a flannel, and we’ll squeeze it into your mouth.”‘)

[As an aside, just from the scanty information provided in this article, the following things in Ms. Radcliffe’s labor went against the World Health Organization’s “Safe Motherhood” guidelines: Of “Practices which are Demonstrably Useful and Should be Encouraged,” she did not have #4. Offering oral fluids during labour and delivery, or #15. Freedom in position and movement throughout labour; of “Practices for which Insufficient Evidence Exists to Support a Clear Recommendation and which Should be Used with Caution while Further Research Clarifies the Issue,” she had #3. Fundal pressure during labour; of “Practices which are Frequently Used Inappropriately,” she had #1.Restriction of food and fluids during labour, #3. Pain control by epidural analgesia, #7. Oxytocin augmentation, and #12. Operative delivery (vacuum assistance). While I do not blame her for getting an epidural (after many, many long hours of Pitocin-induced contractions, without being able to move from the bed), that probably made vacuum assistance necessary. “[T]hings culminated in a wild finale with two nurses pushing on her belly and a suction device on Isla’s head and the doctor bracing one foot against the delivery table in order to yank full strength.”]

In Henci Goer’s book, The Thinking Woman’s Guide to a Better Birth, she discusses IVs in labor (usually a glucose solution) being used instead of the woman being allowed to eat and drink as she wishes. On page 77 she says, “IVs are problematic by nature. Hunger and thirst and our natural responses to them invoke complex balances in both mother and unborn child. These balances are disrupted when they are bypassed by dumping huge amounts of fluids, often over a short period of time, directly into the bloodstream.” Then on page 79 is this, “Dehydration and starvation are associated with longer labors, increased use of oxytocin (trade name: Pitocin or “Pit”) to stimulate stronger contractions, and instrumental delivery. In addition, during pregnancy, starvation causes a faster, sharper drop-off in blood sugar levels and an earlier switch to metabolizing body fat. Vigorous exercise–in this case, labor–accelerates this process.” Then on page 80 is the following, “Glucose-containing IV fluids, also called ‘dextrose’ IVs, can raise maternal and fetal blood glucose levels to diabetic levels (hyperglycemia). Hyperglycemia in the baby increases the production of lactic acid, a metabolic by-product when there is insufficient oxygen.”

So how does this all work together? Here is my summary: Lactic acid is indicative of muscle fatigue (even if it’s not a cause or effect). To analogize, glucose is cash in your pocket that your muscles “spend” in order to work; lactic acid is “money in the bank.” Your body automatically converts glucose to lactic acid, so dumping too much glucose in your system at once (such as with an IV) can be counter-productive because the glucose is too-quickly converted into lactic acid (the “cash” is automatically deposited into your “savings account”); while the body’s normal digestive system allows you to take in a large amount of food and slowly converts it into “cash.” If you run out of glucose (easily expendable cash), then you must do the harder work of getting energy from lactic acid (taking a trip to the bank, waiting in line….). If you run out of cash at the grocery store, it doesn’t matter if you have a million bucks in a money market account–you still can’t buy your groceries because you have no cash in your pocket. Your body can increase the efficiency at which it burns lactic acid, but this takes time and training, neither of which is available in labor. (It’s possible that Braxton Hicks contractions leading up to labor are making the muscle of the uterus become more efficient at burning lactic acid–but this is just my hypothesis.) If your body is not very efficient at “spending” lactic acid, then the overload of lactic acid may make your uterus contract less efficiently–either due to the overload itself, or the fact that your muscles can’t efficiently “spend” the lactic acid, so you’re standing in line at the bank too long, trying to “liquidate your assets,” as it were. Marathon runners (or any athletes, for that matter) speak of hitting “the wall” when they simply can’t go any further. One of the articles I read says that the body has only so much possible reserves of calories to spend, and loading up on carbs before the event can help you overcome “the wall”; but food and drink during competition are necessary, too. As the world-record holder Paula Radcliffe said, “You get to drink at the 5-K mark!” Expert runners can complete a marathon in a few hours, average runners take several hours to complete. Volunteers line the race path with food and drink for the runners to have if they need it. This “quick energy” is enough to keep them going. When women are forbidden to eat or drink during labor, it seems like there is a time when the uterus hits “the wall” and simply can’t keep working under such adverse conditions. (Could you walk, run, or bike for hours without anything to eat or drink? Would that even be considered healthy? Is fasting a good thing for your baby?) Glucose IVs can help, but they can be “too much of a good thing” in a lot of ways, including the too-quick conversion of glucose (which your body is best at burning) into lactic acid (which your uterus is not as used to using). Artificial stimulation of the uterus through Pitocin can force it to contract and may prevent a C-section from being necessary, but this is not always the case.

A better way to avoid uterus fatigue is what midwives have always known and what women have always done (prior to about a century ago, when they started going into hospitals)–eat if you’re hungry, and drink if you’re thirsty.

3 Responses

  1. This is very interesting to think about. I love how you tied it all together with a nice analogy. I agree moms should be allowed to eat and drink if they feel like it. Trust your body, listen to it!

  2. I am curious, how do you get rid of the EXCESS lactic acid in your muscles? thanks IN advance.

  3. As far as I can figure, lactic acid will naturally dissipate over time; and the best thing to make it happen faster is to work out more so that your body gets accustomed to burning lactic acid at a faster pace.

    However, there is still much unknown about lactic acid, so I could be mistaken about this.

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