She was in the 11th week. Between five and fifteen percent of all pregnancies end in miscarriage. The most likelihood of a miscarriage after three successful pregnancies is chance alone. Most miscarriages are due to a problem with egg quality. Eleven weeks is certainly later than usual.
Most miscarriages occur within the first eight weeks after the last menstrual period.
Sometimes, the problem is determining exactly when the miscarriage occurred. It could have occurred several weeks before it was diagnosed. This may be the reason for the eleven week dating. Knowing your past history, the chances of an additional pregnancy should be very good. The ideal cycle is 28 days.