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Week by Week Fetal Development25,976 Views
Fetal Development Week 4 will start in
This is the week most women find out they are pregnant. It is also the time when the embryo is just about the size of a poppy seed. Learn more about fetal development week 4.
Description: Understanding week by week fetal development is important as your baby continues to grow during the first month. Learn more by watching this video.
3 weeks pregnant, 2 weeks pregnant, 1 week pregnant, pregnancy week by week, fetal development
conception, implantation, uterine lining, embryo, blastocyst, fetus, zygote, human chorionic gonadotropin
pregnancy, first trimester, giving birth
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In the beginning, you won’t even know you’re expecting yet. Meanwhile, your baby will be busy moving in! The beginning of pregnancy may be confusing-after all, the first week is medically just your menstrual period. Calculation of gestational age depends on a number of factors and generally assumes a 28-day menstrual cycle length. Because your baby’s expected delivery date is determined from the FIRST day of your LAST period, this week counts as part of your 40-week pregnancy even though your baby hasn’t even been conceived yet! That will happen during the end of week two--again, assuming a 28-day cycle length-when one of your ovaries will release a ripe egg, which will pass into a fallopian tube. There, your egg will wait for 12 to 24 hours for the arrival of one of your partner’s tens of millions of sperm. After the sperm arrives in your fallopian tube, it will combine with your egg, and merge into a fertilized egg, or zygote. It’s interesting to note that it is the sperm that carries the chromosome that determines sex! At this point, the zygote’s sex has been determined by either a male Y-chromosome, or female X-chromosome. At this point, your little zygote will begin the journey from fallopian tube to uterus. As it travels, the zygote will divide until it becomes a mass of 16 identical cells, which-upon reaching the uterus-is called a morula. The morula fills up with what will become amniotic fluid and changes monikers yet again. You’re now carrying a blastocyst. Near the end of your third week after the first day of your last menstrual period, the blastocyst will attach itself to the endometrium, or the lining of the uterus. This process is called implantation and creates an essential connection between you and your baby. The endometrium will eventually develop into what will sustain your baby throughout the pregnancy-the placenta. But in the meantime, this lining will provide nutrients and remove wastes for the blastocyst. The newly implanted pregnancy produces hCG, human chorionic gonadotropin, which tells your ovaries to stop releasing eggs, and triggers the production of estrogen and progesterone. hCG is the chemical which shows up in your urine to turn a pregnancy test positive, so if you test at this point you may already see a positive result. Congratulations, mom-to-be. The end of this third week marks the OFFICIAL beginning of your pregnancy journey.