The median amount of time for a woman to bleed post partum is 3-4 weeks. This means that 50% of women bleed longer than this. It is important to realize that the nature of post partum bleeding (lochia) is often to come and go, and sometimes women begin to count seven clean days only to experience light or heavy bleeding again later in the counting.
If the bleeding persists after eight weeks, we suggest you see your doctor about the possibility of a hormonal solution. Regarding the halachic procedure, seven clean days must be counted before immersion as you would after every niddah period. You may omit the moch altogether the first time, since women are particularly sensitive and prone to spotting after a vaginal birth. If you are still having difficulty counting seven clean days, please write back to us to discuss the possibility of cutting down the number of bedikot for this immersion.
After you have gone to the mikveh, be careful to wear colored underwear or black pantyliners, so that any light, intermittent spotting does not make you niddah again. You may find it helpful to review our article on ketamim (stains).