The ovulation occurs exactly fourteen days before the start of the next expected menstrual period.

However, this is useless when the woman tries to guess the day of ovulation when she conceived or to calculate it in advance if the menstrual cycle length is irregular.


Given the data you reported (your average menstrual period length being 31 days, previous menstrual period start at September 15, you having intercourse with your boyfriend from 01-10 October), there was a chance for you to conceive.


However, the fact that your menstrual period started as usual rules out the chances for pregnancy. Certain women might experience bleeding during pregnancy, but that bleeding usually is not the same in length or blood loss or day it started as the usual regular menstrual period. That bleeding might be a sign of a pathological condition and need an additional examination to prevent a possible miscarriage. Irregular menstrual cycles might additionally complicate the situation.


You might want to visit a gynecologist for a physical examination in order to check for pregnancy. Hormonal laboratory tests and an ultrasound scan might be recommended if the doctor cannot give you an exact diagnosis based on the anamnesis and the aspect of the spotting blood.