What Causes Delay In Periods By One Week After A Miscarriage?

I am a thirty two years old women.I got my first delivery on May'10.But my baby was died one day before the delivery date.After my delivery, the periods were regular.For the past two months(feb'11 and march'11), menstruation cycle was delayed by one week.What is the reason for this delay?Is there any problem to get pregancy in the future?