Pregnancy tests are designed to tell if your urine or blood contains a hormone called human chorionic gonadotropin (hCG). This hormone is produced right after a fertilized egg attaches to the wall of a woman's uterus.

Because sperm can survive in the fallopian tubes for up to a week, you don't have to time sex to the exact moment you ovulate to get pregnant. This window includes the five days before and the day of ovulation itself.

An egg lives 12-24 hours after leaving the ovary

PCOS is a leading cause of infertility in women

Causes of implantation failure include  genetic defects, thin endometrium, embryonic defects and endometriosis.

Emergency contraceptive pills are often called 'morning after pills' and sometimes even 'day after pills' because you can use them after sex to prevent pregnancy.