Hi, Thanks for posting in HCM. I understand your concern. Pregnancy is possible when you have regular menstruation and timely ovulation. When menstruation happens regularly (28 days cycle), ovulation occurs around 13th day. The week between 10th day to 17th day is called fertile period . Hence, when you time intercourse during this fertile period, there is more chances for the ovum to get fertilized. Following fertilization, if the endometrial environment is conducive, implantation occurs, which states that you have conceived. Following implantation, you would miss the period and you can test to detect pregnancy by a week to ten days by undertaking urine pregnancy test. Hope the information provided would be helpful. All the best.