The thing about OBs is, they're SURGEONS. They are trained in worst-case scenarios, and have a hard time, I think, trusting that everything in most women's births is generally going to go fine. Humans don't really NEED episiotomies, or inductions, or (dare I say it?) pain-relieving drugs. Yes, sometimes drugs are helpful to an individual woman, and sometimes (SOMETIMES, not nearly so often as a doctor recommends them) an induction is, in fact, medically indicated. But mostly, research has shown that ANY medication or testing offered in labor is likely to send a woman down the slippery slope that ends in c/section: major abdominal surgery that has enormous risks and impact on both the birthing woman and her baby. One in FOUR pregnant women in the U.S. now have c/sections, a much larger percentage than anyplace else in the world (except, maybe Brazil, from what I've heard) ... and clearly, if the human race REALLY required that kind of intervention to perpetuate itself, we'd have been a dead species for millenia.
Not to say that some c/sections aren't truly necessary. But in this country, way more are done because a doctor wants to get home to watch "the big game" or, more often, wants to cover his ass in case of a malpractice suit. Did you know that OBs have the highest rates of being sued for malpractice of any medical specialty?
Remember that doctors' malpractice insurance as well as hospital protocols drive the way they practice medicine, largely. They're going to suggest tests which, as has already been mentioned here, are MUCH likelier to give you false positives (say there is a problem when there isn't) than false negatives. And if you're in any kind of high-risk group, or even a wisp of high-risk, they're going to push tests in a very big way. Trust me, because I was 38 when I got pregnant the first time, it spun us into a hellish series of tests, many of which have their own risks which the doctors minimize.
Nobody's done a definitive study on whether ultrasounds have any negative effect on babies, didja know that? ULTRASOUNDS, for god's sakes, which pregnant women have routinely without ever thinking they're any more dangerous than, say, peeing in a cup! Ultrasound results are almost never perfectly definitive, and the weight "measure" is up to 10% off every time -- how many women do you know who've been cajoled into inductions or c/sections because of "big babies" that turned out to be only 8 pounds or so? And just having an amnioscentesis can create a miscarriage ... plus, the amnio itself has only a VERY limited range of information which it can give you definitively, again, sending you off in a fear cycle and torrent of further testing, none of which has a perfect capability of reporting what they're testing for.
Sorry to rant, but can you tell this is a big hot-button for me? I spent the last half of my first pregnancy in constant fear that I'd have to be flown halfway across the country for emergency fetal surgery because of a problem they saw on my baby's first ultrasound. I had, if I remember correctly, seven ultrasounds, and ended up birthing my baby 70 miles away in the nearest university medical center ... and he was fine. I wasn't: I was badgered into an induction, and it ended in a c/section.
It takes a LONG time for many women to recover from c/section, and it's not necessarily the outer scars that are the worst of it. My DH and I very seriously considered never having another child after the first. (Our second snuck in when we weren't being perfectly careful, or I'm not sure there would have been a second, because we were seriously considering DH having the Big Snip.)
Anyway, I'll stop ranting now and conclude with my best advice: if you want a midwife and a homebirth, then find a midwife who you can trust and TRUST HER. You'll get better prenatal care, FAR BETTER, from a midwife who will likely spend 30-60 minutes with you in each visit (an OB visit is lucky to last ten minutes); she'll do all the urine testing that you get in an OB office; if she thinks you need further testing, she'll know how to get that for you from a doctor who's less likely to bully you.
Don't let yourself get scared or bullied. And even more than you trust your midwife, trust yourself. Trust your own body to do it's work. In the end, when you're holding your beautiful baby in the privacy and comfort of your own home, surrounded only by people you love and trust completely, you'll be SO glad you did.