Most women will have their menstrual cycles return somewhere between two and six weeks after a D&C or vacuum aspiration. But the exact length of time for return of period after D&C will vary by the person, of course, and possibly by how far along the pregnancy was at the time of the miscarriage (hormone levels return to normal more quickly after an early miscarriage vs. a later miscarriage).
If it's been more than eight weeks since your D&C and you haven't yet had a period, tell your doctor. Most likely, there isn't a serious problem, but a small number of women will develop intrauterine adhesions or scarring following D&C -- with the highest risk being in women who have had more than one D&C. Scarring in the uterus, or Asherman's syndrome, can cause future fertility problems if not treated, so your doctor may want to rule out the condition to be on the safe side. Don't be afraid to seek a second opinion if you feel you need to.
A slow-to-return menstrual period can be frustrating, especially if you're hoping to begin trying again for a new pregnancy, but the good news is that most research has shown that future fertility is roughly the same following all three miscarriage management methods -- so once your period does return, chances are that you shouldn't be at any higher risk for future problems.¨
D&C Procedure After a Miscarriage. American Pregnancy Association. Accessed: Jun 2010. http://www.americanpregnancy.org/pregnancycomplications/dandc.html
Patient information: Dilation and curettage (D and C). UpToDate. Accessed: Jun 2010. http://www.uptodate.com/patients/content/topic.do?topicKey=~I0_xdOQQHEMvf_
Smith, Lindsay FP, Paul D Ewings, Catherine Quinla. "Incidence of pregnancy after expectant, medical, or surgical management of spontaneous first trimester miscarriage: long term follow-up of miscarriage treatment (MIST) randomised controlled trial." BMJ 2009;339:b3827.