Well it is a long time since I had my babies, and broke my leg, but to those of you who say that Entonox is useless, I have to suggest to you that you weren't breathing it in properly. I know that many things can be down to personal opinion, but with chemical and biological reactions, I thought that the results were well acknowledged and documented.
Of course, even if that is so, things like someone's size, their lung capacity, the health of their lungs and the state and quality of the different elements of one's blood, along with the efficiency of their hearts, could all have some affect on the absorption in the body of the gas (Nitrous Oxide) and the air (Oxygen) (50% of each make the gas and air mixture, Entonox). However, even taking into account all of those differentials in each person's body, unless you were not breathing the gas and air mixture all the way into your lungs, it had to have some affect on you.
I must have been breathing it in properly, because I bloody loved the stuff - I had my first baby because I wanted a baby, but I had the others, and broke my leg, because I wanted the Entonox! But in all seriousness, has the Entonox really been causing miscarriages and fertility problems in midwives for at least the last 50 odd years, and if it has, why has it taken so long for "them" to realise what was causing the problem?
I do think that if Entonox really is the problem, has something like it's delivery to the mums to-be had any drastic changes for "them" to only be aware of the dangers more recently? If it is just a matter of needing better ventilation in the labour wards and delivery rooms, surely that can be implemented very quickly, as there are already many other instances where fresh and clean air is of paramount importance, so the mechanisms for providing that are very well established.