3 Weeks Pregnant - What to Expect

Explore the process of early pregnancy, from fertilization to the determination of X and Y chromosomes. Learn more about week 3 of pregnancy: https://www.whattoexpect.com/pregnanc... Track your baby's growth with the What to Expect App: https://wte.onelink.me/85iI/29dt1g98 Transcript: Congratulations! You've conceived. Your soon-to-be baby has started its transformation from one single cell to fully-formed baby boy or baby girl. Within a matter of hours after sperm meets egg, the fertilized cell, called the zygote, divides into two and then splits again and again. Seventy-two hours after fertilization, the zygote has become a ball of 16 cells. This microscopic cloak is called the morula, Latin for “mulberry.” And if you think about it, that ball of cells does look a little bit like a berry. Over the next few days, the morula continues to drift down your fallopian tube, dividing during its journey into a blastocyst, a cluster of rapidly dividing cells. Its final destination is your uterus, which it will call home for the next nine months, give or take, as it morphs from blastocyst to embryo, to fetus, and finally to baby. It'll be a while before you're able to tell whether your tiny blob of cells is a boy or a girl, but its sex was already determined at conception. The egg always supplies an X chromosome, but the sperm provides either an X or a Y chromosome. Two Xs make a female, and an X plus a Y makes a male. Soon enough, though probably not soon enough for you, you'll be able to find out which winning letter combination you have growing inside of you.