The menstrual cycle

During the last few daysTrusted Source of a period, the pituitary gland stimulates the production of follicle stimulating hormone (FSH). This triggers the development of eggs in the ovaries.

Next, luteinizing hormone stimulates the release of the egg from the ovaries into the fallopian tubes. The lining of the uterus begins to thicken to prepare for a potential pregnancy.

A person becomes pregnant when sperm from a male fertilizes the egg. Sperm can live in the reproductive tract for several days, so it is possible to become pregnant before and slightly after ovulation.

Ovulation is not always predictable and can happen early or late. So, it is theoretically possible for someone to become pregnant at any point in the menstrual cycle.