Feel free to elaborate in comments.
How much experience?
Poll Results: In your opinion, at least how many years experience should a midwife have before considering one for a homebirth?
Personally, I don't think overall quantity or time is as important as quantity or outcome of experience. For example, a midwife could have been working for/apprenticed with a very busy practice and do 50 deliveries a year, or one in a more rural area might have been involved with 10 or less in a year. Also, the individual experience is important (Has the midwife seen a breech delivery? What issues has the midwife seen/dealt with?).
Also, I think it would depend on the individual circumstances surrounding the home birth. I live in an area where it would be 15 minutes/minimum to get to the hospital in an emergency situation. If I were considering homebirth (I have had one natural birth in a non-hospital associated birthing center, and hope for the same this time), I would feel that I would want a more experienced midwife than if I were, say, only 5 minutes or less from emergency services.
I voted 6+ but agree with the pp that this is a difficult question to answer. Obviously MWs have to get their experience somewhere, right? I would not personally be comfortable with a brand new MW but I would be OK (I think) with a recently practicing HB MW with years of experience in some other professional way that saw a lot of births, like a L & D nurse or something like that. I would obviously factor education into that equation.
We used a new graduate for our first home birth last year. Incredibly, as we found out later, she was only 23 - she seemed to be way, way beyond her years. We were initially nervous about using a new grad - we'd initially booked with a part time midwife/midwifery lecturer at the same practice - but our fears were unfounded. Her knowledge was right up to date, she wasn't afraid to get a second opinion if she was ever unsure, and she'd already sat in on a number of home births before attending ours (home births are usually attended here by two midwives, although in the case of this practice it was two new graduates which I thought was unusual). I loved her style - she would tell us our options, give us her professional opinion and then say "What would you like to do?". It was true informed consent in action, something I've never been lucky enough to really witness before. Ultimately she missed the birth by minutes - it was no fault of hers, but the pager system where ironically, an older more experienced midwife on call decided on the phone that my contractions weren't lasting long enough to be productive - until I was ready to push! But she was an incredible help in the immediate postnatal period and weeks that followed.
I honestly think it has as much to do with open-mindedness, personality and a willingness to learn as it does to do with experience. People can take their experiences and become cocky from them - such as in the case of the experienced midwife who'd never had a labour progress like mine and obviously didn't think contractions 30-60 seconds long, three minutes apart, were enough to get a baby out. We're now seeing another young, but slightly more experienced midwife, who has me worried - her knowledge seems to have gaps in it that she lacks the self-assurance to fix. She's not a good listener and I find myself repeating things over and over as she's recorded the details wrong. And on the flipside, my friend recently had a midwife of many, many years experience whose knowledge was probably a good 10-20 years out of date, who caused a severe tear when she tractioned the shoulders during a home birth. Trust your gut, is all I can say. This is someone whom you'll be intimately involved with and placing a lot of trust in, when you're most powerless to defend yourself. I don't think a decision like this should ever be made on the basis of years of experience alone. Protocols change, and it's just not a good indicator in isolation. I'd still go with the university lecturer in a heartbeat - she was warm, listened, and teaching others keeps your knowledge fresh.
It's a tough one to answer. I'd look at the whole curriculum vitae before making a decision. In other words, I would look at a few key areas.
1. What kind of training has she (or he) had? If she has only done bookwork and not seen very many births, I would be leery of using her for the main midwife at a homebirth until she has had more experience. However, if she has worked in an apprentice-like fashion under another midwife, then I would feel more confident that she will be more prepared even if she was not the primary provider at the birth. After all, many doctors have no experience with natural childbirth before they start practicing (as an intern or resident). To go along with this, often the more recently they had training, the more up to date their knowledge & practice will be, so while they may make small mistakes, they often try their best to do as much research as possible before going into a situation & the knowledge is fresh in their mind rather than a distant memory of "I know I saw something like this when I was training a decade ago."
2. How many births has she witnessed (not necessarily as the primary but at least observed)? As above, many work in apprentice-like situations where they observe and assist at many births before they are qualified to be the primary provider at the birth. Even then, some will have a second midwife with more experience there to supervise.
3. How often does she do continuing education? A lot of experience is awesome and can in no way be replaced by just book learning, but standard of care practices can and do change, sometimes rapidly, and a good provider will keep as up to date as possible (either with continuing education classes or by subscribing to & reading publications by their professional organizations). Also, there are just some situations that do not come up very often, so I would certainly want someone who makes sure to keep their knowledge fresh on some topics so that they can be as prepared as possible to take appropriate care in those rare situations. (ie, shoulder dystocia may not be very common, but the provider should keep up to date with training on how to guide the mother into positions to help open the pelvis as well as re-training on how to do the Gaskin maneuver, McRoberts maneuver, or even how to break the collar bone if the other less drastic measures do not work to bring the baby down.)
4. How connected is she to the midwifery contacts in the area? Again, some situations don't come up very often, so a good midwife should try to know as many midwives in the area so she can bounce ideas off of each other, learn from other's experiences, and know who to refer you to should they be uncomfortable with your requests or special situations.
5. If she has not had the opportunity to provide for or witness a specific "non-normal" birth (ie breech birth, extended bleeding, twin vaginal birth, etc.), does she do reseach to prepare herself in case it happens and try to work with other midwives who have seen this in their practice?
All in all, you need to look at as many aspects of the midwife & her training as you can. Sometimes you find someone that you are totally comfortable with & who puts in a lot of time training herself & learning as much as possible about birth & babies but who does not have a ton of experience yet. On the other hand, you can have someone who appears to have a lot of experience but does not keep up with current practice & doesn't re-train herself on the things that are not super common but can happen. It's true in every profession that sometimes a green newbie is actually a better choice than the apparent seasoned veteran and vice versa.