This is the week it happens. A single sperm meets the egg in the fallopian tube, and fertilization occurs. Within hours, the fertilized egg begins dividing. By the end of the week, this tiny cluster of cells is making its way toward the uterus.
Your Baby This Week
Size: Smaller than the tip of a pen (0.1 to 0.2 mm)
Right after fertilization, the single cell (called a zygote) starts dividing rapidly. By day 3, it has become a ball of about 16 cells called a morula. By day 5 or 6, it has developed into a blastocyst, a hollow ball of roughly 100 cells with an inner cell mass that will become your baby and an outer layer that will become the placenta.
The blastocyst travels down the fallopian tube and reaches the uterus, where it will begin to implant into the uterine lining.
Your Body
You will not feel any different yet. It is far too early for pregnancy symptoms. A home pregnancy test will not show a positive result this week because the hormone hCG has not started circulating in significant amounts.
Behind the scenes, progesterone from the corpus luteum (the empty follicle left after ovulation) is keeping the uterine lining thick and receptive.
What to Do This Week
- Keep taking folic acid. Neural tube development starts very early, and adequate folate is essential.
- Avoid known risks. If you are trying to conceive, steer clear of alcohol, smoking, and high-mercury fish.
- Be patient. There is nothing to test or confirm yet. The two-week wait between ovulation and a missed period is the hardest part for many people.
Common Questions
When does implantation happen?
Implantation typically occurs 6 to 12 days after ovulation. Most commonly, it happens around day 9. Some people experience light spotting or mild cramping during implantation, but many feel nothing at all.
Is the baby's sex determined already?
Yes. The sex is determined at the moment of fertilization by the sperm. If the sperm carries an X chromosome, the baby will be female (XX). If it carries a Y chromosome, the baby will be male (XY).