I didn't have it (I had an emergency CS before going into labor) but I gave birth in the UK where Entonox is standard. In fact it's available in midwife-led units and at home birth, which would probably not be allowed in the US because of liability, and it's actually considered a "normal vaginal delivery" if you use it.
I think it is useful but with some major limitations. I personally do not like the effect of nitrous (I've had it for dental work) so if you really dislike anything that makes you feel detached, or loopy, or out of it, Entonox will probably not be a good choice for you. However, I know of quite a few cases where it took enough of the edge off contractions to get the mother through. The descriptions I've heard aren't that nitrous kills the pain completely--it blunts it and makes you not care. I've heard it described as a "detached" feeling. There does come a point at which Entonox just doesn't cut it, particularly if what mom needs is a break so she can sleep or rest (Entonox has a very short duration of action; once you stop sucking, it stops working). You need to time it correctly to get the most benefit, so it's at its peak during the contraction. That short duration has its positives: If you hate it, just quit sucking on the mouthpiece and it will wear off quickly. It's not like an epidural or narcotics where you need to wait for it to wear off. So, you really have little to lose by trying. IME, the long, tough labors I saw in the UK wound up with an epi the same way they did in the US. The easy to average labors were more likely to skip it in part because of Entonox.
I used it with DD.... sort of. I used it wrong and didn't actually get the physical effect of the gas - as I found out after the birth, when my placenta had to be extracted with forceps and the MW kept telling me "suck more gas", and I was all "Ohhhh, this is what they meant!". :p Psychologically, though, I did feel more in control while I was holding the tube, knowing I could suck on it if I wanted... it kinda gave me something to do, and also something to resist ("I can get through this next contraction without it").
I'm planning to do Hypnobabies this time, waterbirthing and so on, and obviously I'd prefer to go all-natural; but our birthing centre offers nitrous, and I won't feel bad about using it if I need to. It doesn't cross the placental barrier; it's user-controlled, not controlled by a nurse or anything; it wears off very fast (I think it exits the body in something like 7 seconds - or is it 7 breaths?); and as far as medical pain relief goes, I don't think it has anywhere NEAR the implications of an epi or even pethadine or whatever.
That said, yes, it does alter your mental state - when I was using it properly I definitely had that "Wow, this is agony, but I don't care" thing going on, which was a rather unusual sensation! (Given the alternative, though, I was happy with it...) I can't imagine using it for several hours at a go or anything, which is why I'm planning to use it only if necessary and as a last resort. Your "security blanket" definition is a good one!
And yeah, learn from me - if you do use it, keep taking breaths of the gas. Don't stop as soon as you "feel funny". You're supposed to, that's the point. :p (I mean, obviously, stop if you feel sick or whatever - but I was so out of it with labour-land and lack of sleep that I kept thinking "Ooh, that feels a bit odd" and stopping. Silly me.)
This is so true - it hurt just as bad but as you just didn't care.
I had an induction with DD and went into it afraid of induction contractions - everything I had heard was that they were more painful than natural contractions. I also was very slow to progress for the first 8 hours or so. So, I was in huge pain and everytime they checked me I had barely dialated and would ramp up the pitocin, which would scare me more because I knew it would hurt even worse and who knew how long it would take because all that pain 'wasn't doing anything'.
Anyway, I was trying to avoid an epidural and agreed to try the gas....and I wish I hadn't, honestly. Yes, you care less about the pain....but time also goes all crazy. For me, I felt like I had been using the gas for an hour at least and when I asked how long it had been? 10 minutes. Cue more panic about the pain never ending!
I have some reservations about nitrous oxide. There has been research published which found that NO use in labour increased the likelihood of amphetamine addiction (in the child) later in life.
Are your midwives going to be using Entonox or a nitrous oxide mixer? Entonox is the trade name of a 50:50 nitrous oxide:oxygen mix. IT comes pre-mixed any you can't adjust the ratios. Entonox is typically used in ED and dental surgeries for minor procedures.
Birth suites in Australia typically use mixers which allow the midwife to tailor the mix to the woman's needs. From memory, the lowest dose is 30:70 and you can go all the way up to 70:30.
I just read that last night! Michel Odent mentioned it in his book. I thought of this thread. :p Honestly though... amphetamine addiction just isn't that high on my list of things I worry about in my children. I mean, it's not like an increased risk of schizophrenia or something; it's drug addiction, and surely there must be a LOT of nurture factors at play there? (Also, the way it was phrased in the book, it was unclear whether or not nitrous oxide was considered separately from the other labour drugs mentioned, or not. I couldn't tell whether it was "babies whose mothers used, W, X, Y and Z pain relief during childbirth as a whole had a higher risk of amphetamine addiction than babies born with no drugs/gas at all", or whether each drug was individually associated with the higher risk. Anyone?)
There has been some research published on just nitrous oxide. It was done in one of the scandanavian countries IIRC. They studied siblings whose mothers had used NO for one birth but not the other. If you Google nitrous oxide + amphetamine addiction you should find the abstracts at least. I will see if I still have copies of the papers I read.
Different people metabolize it differently... my only personal experience with it is from dental work. My mom gets drunk as a skunk (her term) if she uses nitrous and after two exposures she now refuses it completely. I find it effective in that "this hurts but I don't care" way and have never had any significant negative side effects (my mom throws up, feels hung over, etc while I feel fine in about 5 minutes and only mildly loopy during use). My 6yo dd1 who unfortunately inherited "my family's" teeth has had nitrous twice now for extensive dental work and she loves the stuff. She says she feels dizzy and then everything is all done... in her case the time dilation works in a positive way with hour long procedures "feeling like" a few minutes.
In terms of birth... it's a very common intervention and so there is a lot of BTDT feedback as well as a huge population for study. I know moms who choose their birth site based on nitrous availability, even if they don't plan on using it they want that option. And I know moms who hate the stuff! I doubt they'd let you stop by to try it out before the birth to see how it works for you LOL but I probably wouldn't ban it from my own list of progressive interventions. I'd probably go with hypnobabies with something like belly dance/birth ball/rocker/walking, then shower/tub, then TENS unit, then nitrous, then IV narcotic, then epidural, than surgical delivery. But that's me and you'll have your own list of acceptable risk/benefit rankings!
Putting on my reference librarian hat for a moment, I think this might be the study in question:
Socio-economic versus obstetric risk factors for drug addiction in offspring
Department of Clinical Alcohol and Drug Research, Karolinska Institute, Stockholm, Sweden.
Here's the abstract that's available through PubMed, the bolding is my own. At least in this case nitrous was not seperated from other drugs used during the birth though the eventual type of addiction was divided between opiates and amphetamines. And at least in this study amphetamine use seems to be influenced by socio-economic status as well. Also important to note is the type of study... they reviewed records from 1945-1966 so there are LOTS of things that may not have been accounted for (like birth trauma, maternal health during pregnancy, method of feeding the infant, etc). Those were also pretty unusual decades and the differences between siblings may have roots beyond birth method or socio-economic status alone.
Two possible risk factors for drug addiction were weighed against each other: (1) perinatal factors associated with obstetric medication at time of birth; and (2) factors associated with familial socio-economic conditions at time of birth. The subjects comprised 200 amphetamine addicts and 200 opiate addicts born in Stockholm 1945-1966. In a matched case control study, addicts were compared to their siblings with regard to possible obstetric risk factors by means of conditional logistic regression controlling for socio-economic level and civil status. Administration of opiates, barbiturates and nitrous oxide to mothers during labour was associated with drug addiction in offspring, hence confirming results from earlier studies. In a cohort study the risk associated with birth at a given hospital and familial socio-economic level was analysed by means of log-linear analysis using 7100 controls from the general population. For amphetamine addicts, a low socio-economic level at time of birth might be of importance for the infant subsequently becoming an addict. This could not be demonstrated for the opiate addicts. An uneven distribution of births among the hospitals, most pronounced for the amphetamine addicts, is in agreement with the hypothesis that obstetric practices may be risk factors for adult drug addiction.
My sister loves it. It's funny - my family's pretty conservative, and I'm pretty sure we've never had so much as a whiff of marijuana or cigarette smoke between us, but let my sister at the nitrous oxide and whoo! I swear the day she broke her leg was the best day of her life. :p And my eminently respectable mother was actually looking forward to her throat surgery so she'd get morphine afterwards (sadly, that time it made her throw up; she was very disappointed).
Personally I liked the effect of the gas, but not the metallic taste I got from sucking it. I wouldn't feel tempted to take it recreationally, but for the purpose of having my placenta removed with forceps, it was super.
LOL that's too funny! After my c/s (and then my 4th degree tear/repair) I had a sudden insight into how addictions happen. I respond reeeeeaaaaaallllly well to percoset and that warm fuzzy feeling was hard to give up at the end of my dosage week. I'm pretty mainstream in my recreational choices a well (a glass of wine with dinner, a few beers at a BBQ, that sort of thing) but if my doctor had offered another week of percoset I really don't know how I would have responded!