How long does it take from ovulation to implantation? The answer depends on several factors, but if you understand the process, you should be able to estimate approximately when implantation will occur, and when a pregnancy test will be accurate.
When your hypothalamus detects low estrogen levels at the beginning of your menstrual cycle that indicate the absence of a mature egg in the ovaries, the hypothalamus signals the pituitary gland to release follicle stimulating hormone (FSH). This hormone tells the follicles, or small sacs that contain immature eggs, in the ovaries to start preparing an egg for ovulation. When an egg matures it begins to produce estrogen, which tells the hypothalamus it’s time to trigger ovulation. The hypothalamus tells the pituitary gland to release luteinizing hormone (LH), which prompts the mature unfertilized egg to leave the ovary and begin its trip down the fallopian tube. This is the moment of ovulation.
The egg can survive for approximately 24 hours in the fallopian tube. If it’s fertilized during this period, it resumes its journey down the fallopian tube to the uterus. If it isn’t fertilized, it dies and is absorbed by the uterine lining, which is expelled during the next period. Because sperm can survive for up to three days in the female body, sometimes there is sperm already waiting for the unfertilized egg in the fallopian tube before ovulation even takes place. If intercourse takes place after ovulation, it can take anywhere from half an hour to two hours for the sperm to travel from the vagina to the waiting egg.
Once sperm meets egg and conception occurs, the resulting blastocyst finishes the journey to the uterus and implants into the uterine lining. Soon after implantation occurs, the embryo begins producing human chorionic gonadotropin (HGC), a key pregnancy hormone. HGC is also the hormone that pregnancy tests detect. Implantation can occur anywhere from six to 12 days after ovulation, with it taking an average of about 10 days. However, it can take a couple of days after implantation for the body to produce sufficient levels of HGC for pregnancy tests to measure. It’s generally recommended that women begin testing for pregnancy approximately 10 to 12 days after ovulation.