There is not mercury in Rhogam. The last batch that had any thimerosol in it expired over five years ago now. Long gone.
I am sensitized and there's a reasonable chance I would not be if I had gotten the prenatal dose as well as the postpartum dose I got after my first birth. I do have regrets that I didn't get the prenatal dose, big regrets. I have big regrets now, and my pregnancy is actually going about as well as you could expect it too. I cannot imagine how horrible I would feel right now if it wasn't going so well.
Once you're sensitized things may still go relatively smoothly (or they may decidedly not). But one way or another you're high risk and need to be followed accordingly. Homebirth won't be a realistic option anymore with most midwives and in most locales. Your babies will be at risk of anemia and worse complications that can derive from the process, up to heart failure and beyond. The baby may need transfusions before or after birth. Fortunately good high risk OBs/perinatologists are able to head the process off at the pass most of the time now and most babies survive with few or no long-term consequences. But it does mean a lot of monitoring and possibly, if things go south, a lot of intervention.
Before Rhogam rh- women would frequently have a healthy child, then have many, many heartbreaking miscarriages or other losses. I talked not too long ago with a midwife who has been practicing since before it was commonly given and she had some sad memories to share. I have friends whose moms or grandmothers lost half a dozen pregnancies because of Rh sensitization before Rhogam or other treatments were devised. It's one of the true miracles of modern science and honestly looking at the "skeptical" writings on it I don't see anything that suggests it could be anywhere near as harmful as omitting it would be.
Oh and FTR I had NO known risk factors for my blood to have mixed with this baby. No car wrecks, no falls, no high blood pressure, no signs of placenta problems, no diabetes.
