you may not even need it if this is your second pregnancy. im rhneg but sensitized because after my last miscarriage i was given the rhogam, in the thigh. you dont need it if you have already been pregnant and had it, as long as you had it AFTER there would have been a swap of blood, ie delivery, miscarriage. they give you the shot in case there is a chance of your blood mixing with the babies, which would only happen after abdominal trauma, unexpected bleeding during pregnancy and delivery. you have up to 72 hours AFTER bleeding to get the rhogam shot and have it be effective in counteracting any negative effects blood mixing could have on you or your baby. and there have been side effects on babys born to mothers who have had the shot while preg. if you google it you'll find dozens of forums on the subject. do what you feel is best for you. no one knows whats good for you or your baby but yourself.
You can get it in the vein or arm or butt muscle... I had mine given in the vein. I had no obvious side effcts and This was 3 weeks ago just about, when I got the winrho shot. That is what it is called in Canada. It was like nothing was injected. But that is just me.. Everyones different but most ppl who get it have no reaction. My dose was only 300 mcg I think that is standard.
I am RH negative, too, and this is my second baby. I got the Rhogam shot just this last week. It is a very mild shot in the butt cheek; it hardly hurts at all. I have never experienced any side effects or complications from the shot and neither have either of my boys. :-)