I wouldn't say getting pregnant whilst obese was unethical, maybe unwise?
Sure there are many conditions such as hormone irregularities that increase a persons chances of being obese but 99.9% of obese people can do something about it, although that is likely to be much harder if you are dealing with a chronic condition. You don't know your pregnancy is going to be uneventful, statistics alone show that getting as near to an ideal bmi as possible makes this more likely.
Also yes this isn't just directed to obese women, maybe the title should have been anyone with an out of normal bmi? I am underweight, even now at 23 weeks pregnant I have a bmi under 20, yet I have no eating disorder, I have awhat was originally considered a hyperthyroid but has now been found to be a problem with my pituatory. It was caused by childbirth with my first. So I know that it is not always possible to get to that range but I do know how important it is. I try so hard to keep myself gaining weight, pregnancy helps and my babies have all been big but all preemies. My weight may have something to do with this but it may not.
I know for me to get in that range is impossible, if I waited I most likely would only have 1 child, not expecting #4. I know the risks though which is why I work so hard, and seek the support of many specialists.
If you can do something about it you should, and if you can't, seek further medical help to get yourself as healthy as possible
This is completely rambled btw, im knackered lol really hope I don't upset anyone, these things are very emotional