How does pregnancy happen from intercourse?
Pregnancy has a lot to do with the menstrual cycle and the ovaries. The female reproductive system typically has two ovaries, one on each side of the body. Each month a group of eggs, or ova, develops inside the ovaries.
Around two weeks before the next period starts, one egg is released from a part of the ovary called a follicle. This process is called ovulation. At that point, the egg begins its journey down the uterine tubes towards the uterus (also known as the womb). This single egg stays in one of the uterine tubes for around 12–24 hours — this is when the egg can become fertilized by a single sperm.