"The exact length of time for hCG to leave your system after a miscarriage depends on how high the hCG level was at the time that the pregnancy stopped developing.
The average span of time is that the hCG can disappear from your system in anywhere from 9 to 35 days. In general, a woman who had a very early miscarriage is likely to have her hCG return to zero faster than someone whose loss occurred later. "
American Association for Clinical Chemistry, "hCG: Common Questions
I read that you can't ovulate until you hCG is back at 0. I had my 1st post miscarriage af at 5wks and 5days and my usual luteal phase is 14 days. That probably means my hCG was at 0 and I ovulated at 3wks 5days. On another forum, someone took a poll to see when women had their 1st af and most answered that they had it 5 to 6 weeks after miscarriage (d&c or natural passing).
at 1:38 PM on Apr. 8, 2009