Lately there has been a lot of attention around nitrous oxide administration to birthing women. There is especially applause coming from the so-called natural birth community. Midwives, freestanding birth centers and doulas are very excited about this new option for pain management during labor. In reality, there is nothing new about it. Nitrous oxide has been used for over 100 years for labor pain management. Its use is most common in the United Kingdom, Australia, and Canada.
The problem with fanfare over a seemingly innocuous medication is that it is often accompanied by a failure to acknowledge the true risks. Discussion of the impact drugs have on a physiological process is drowned out in favor of "choice" and "support" of women's options. Frequently the rhetoric includes defending the mother's right to not be a "martyr" or that this is a harmless way to relieve anxiety. Any drug that alters our mental state or physical sensations is interfering with our physiology. That's the very definition of what they do--otherwise, they would be ineffective.
This study is often cited in support of nitrous during labor: http://www.cochrane.org/CD009351/PREG_inhaled-analgesia-for-relieving-pain-during-labour. The problem with this study is that it only compared physical side effects and analgesia: "Inhaled analgesia appears to be effective in reducing pain intensity and in giving pain relief in labour. However, substantial heterogeneity was detected for pain intensity. Furthermore, nitrous oxide appears to result in more side effects compared with flurane derivatives. Flurane derivatives result in more drowsiness when compared with nitrous oxide. When inhaled analgesia is compared with no treatment or placebo, nitrous oxide appears to result in even more side effects such as nausea, vomiting, dizziness and drowsiness. There is no evidence for differences for any of the outcomes comparing one strength versus a different strength of inhaled analgesia, comparing different delivery systems or comparing inhaled analgesia with TENS." So essentially, nitrous oxide is not very effective at managing pain.
Pain control aside, the deeper consideration is that nitrous oxide depletes the body of essential B12. I'd love to know what the lab values were for B12 and glutathione in babies and mothers who receive nitrous oxide--this study didn't look at that (nor have any other studies). It's also imperative to know each mother's (and baby's) methylation status and any possible gene mutations. B12 deficiency is extremely common in people with MTHFR mutations, and it is estimated that 40% of the population has a MTHFR mutation.
Lactation actually increases the maternal demand for B12. B12 deficiency in infants is potentially irreversibly debilitating. Infants with B12 deficiency are at risk for anemia, irritability, anorexia, and developmental regression. Colostrum is supposed to be exceptionally high in B12 because infants do not have large stores of vitamin B12. We know the placenta is a very efficient transporter of vitamin B12 because levels have been tested higher in the cord blood than in maternal blood. That's another excellent reason why the practice of early cord clamping should be abolished. So if the mother's B12 is completely wiped out by nitrous oxide (which it is), were are putting these newborns at risk when administering nitrous oxide to mothers. Symptoms of B12 deficiency in infancy often don't appear until 4-6 months, which the Cochrane review referenced above never examined.
B12 concentrations aside, the neurological damage that is occurring in infants should be of great concern. Read more about that here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4066238/
Lastly, whether or not DNA damage is happening from a one-time exposure is something that is still being studied, but if you are in the room of patients receiving this treatment, you are being harmed by oxidative stress from nitrous oxide in the ambient air: http://www.ncbi.nlm.nih.gov/pubmed/22085808. Unless the gas is exhaled back into the mask, which I imagine no birthing mother wants to wear continuously, the nurses and doctors are exposed to hazardous amounts of nitrous oxide.
It can take several months for B12 levels to come back to normal. Most prenatal vitamins contain B12 in the form of cyanocobalamin, which is useless. Methylcobalamin is the most active form in the human body and that is what people should be taking. Also, generally sublingual supplementation is the most effective.
The issue of pain management can be addressed without dangerous medications. Not to mention how important the mother's mental state is during labor--anything disrupting that has great consequences. Interventions like this offer little (if any) benefit and carry great risk--risk that has never actually been studied for its long-term effects. Anything the creates a disconnection between the mother and her body or baby is a risk.
So many people get so excited over nitrous oxide. Everyone assumes it's low risk or risk-free without doing any research on the topic more than "other countries do it." Or "it's better than an epidural." The fact is that many women will choose pain relief drugs no matter what the risk. That truly is their choice and their right. However, they should at least understand that risk. No one should be told any drug is risk free and no one should have the risk minimized to save their feelings. If you want that option, understand it. That's all. And then have at it. 😉