From here, the zygote will move down the fallopian tube and into the uterus. Fertilisation is the time one is said to have conceived a child. Between four to six days after conception, the fertilized egg will develop into a blastocyst and burrow into the inner uterine lining, also known as the uterine endometrium, attaching itself firmly. Hence when one is trying to trace the time for conception, one can take into account up to six days from the day of unprotected sexual intercourse for the sperm and egg to join and form a fertilized egg. Following that, it is another six to ten days’ time for the fertilized egg to completely implant itself in the lining of the uterus. Pregnancy begins during implantation when the hormones needed to support and sustain pregnancy are released (hence pregnancy tests measure the amount of pregnancy hormones released to determine if the woman is pregnant or not) In this early stage, the embryo develops a yolk sac, which provides its first nutrients. But as the tiny being grows, it will turn to its host (mother) for sustenance. Tiny villi, or fingers of tissue on the outside of the fertilized egg, multiply in these early weeks. They go on to make connections with the capillaries in the endometrium, which is concerned with the supply of nutrients and removal of wastes. Over time this mass of cells will become the placenta, which will nourish and protect the baby throughout your pregnancy.

During the process of implantation the tiny embryo is actively secreting the pregnancy hormone known as human chorionic gonadotropin (hCG), which prevents women from menstruating and expelling the embryo from their uterus. In a blood test, hCG will show up as soon as six to eight days after one ovulates, indicating that one is pregnant. However, one should not conclude that one is pregnant based on how one feels. The signs of early pregnancy resemble premenstrual symptoms, and include breast swelling and tenderness, bloating, nausea, and fatigue.