In Depth Baby Product Reviews Led by a Pediatrician

Go Zygote Go!

Your fertilized egg takes a long trip to implantation
Go Zygote Go!
Credit: designua ©
Thursday September 19, 2019

The little clump of cells destined to be your baby is the size of a grain of salt after the egg and sperm met about a week ago. This tiny fertilized egg is called a marula and is on its way toward becoming a blastocyst and implanting in the uterine wall. A portion of the blastocyst is destined to become the placenta; this part produces the human chorionic gonadotropin hormone (hCG), which is the hormone that elevates when you are pregnant and creates a positive result on a pregnancy test. Shortly after fertilization, the egg follicle becomes home to the corpus luteum, a yellowish collection of cells left of the egg. This corpus luteum produces progesterone and estrogen to nourish your future fetus until the placenta is matured and can take over at about 10 weeks. While still in the fallopian tube, this newly formed zygote will divide into 32+ cells called the blastocyst. Traveling to the uterus will take 3-4 days and another 2-3 days to firmly implant. What a trip for a little clump of cells to take! Soon the blastocyst will be an embryo and growing placenta, but right now, it is the size of a pinhead. Your little pinhead won't be called a fetus until week 9.

What happens after the egg is released is shown step-by-step in the following video:

If your fertilized egg doesn't make the journey and instead implants elsewhere, commonly the fallopian tube, it is called an ectopic pregnancy. As the ectopic pregnancy progresses, it can rupture the tube causing life-threatening internal bleeding. An ectopic pregnancy is never viable and cannot be moved, nor will it move independently. Early detection is important and it can be treated with medication or surgery depending on your specific situation. If you suffer any of the following symptoms, you should go to your local emergency center for help:

  • Sudden, intense pain in your abdomen or pelvis
  • Pain or pressure in your shoulder (this is caused by internal bleeding)
  • Feelings of weakness, dizziness, disorientation, or actual fainting


Reference Sources

  1. American Pregnancy - 3 weeks pregnant
  1. WebMD - Understanding Conception
  1. American College of Obstetrics and Gynocology (ACOBGYN)- Ectopic Pregnancy
  1. American College of OB and Gyn (ACOBGYN) - Article on How Your Fetus Grows During Pregnancy

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