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week 1-3
The embryo is now known as a blastocyst. Implantation into the uterus occurs at the end of the first week. Then the embryo turns into a baby or a placenta(the placenta is forming). During the 3rd week, the nervous system begins to form and blood vessels begin to develop.
Info from: Langman's Medical Embryology by T.W. Sadler; Fifth Edition. -
weeks 4-5
The heart begins to beat at week 4. Also, all major organs and organ systems are formed. Finally, arms and legs are growing during week 5.
Info from: Langman's Medical Embryology by T.W, Sadler; Fifth Edition -
week 6
The arms and legs are continuing to develop. The feet and hands are webbed. Also, the lungs are beginning to form, and most of the fetus's vital organs are developed.
Info from: Sex Ed packet -
week 7
At week 7, hair follicles are forming. Also, all the necessary organs have begun forming.
Info from: Sex Ed packet -
week 8
At 8 weeks, the fetus's brain is already forming and growing. The fetus is developing quickly.
Info from: Langman's Medical Embryology; Fifth Edition -
weeks 9-12
At weeks 9 to 12, the ears, nose and eyes are forming rapidly. Also, the kidneys are beginning to form inside the fetus.
Info from: Langman's Medical Embryology by T.W. Sadler; Fifth Edition -
weeks 13-16
At 13 weeks the fetus is the size of a peach 2.9 in. and 81 oz. Also at 16 weeks the fetus is the size of an avocado 5 in. and 4 oz. the fetus starts moving around, the bones become harder, all major organs are developed and are working, fine hair called lanugo develoups on the head, and genitals are recognizable.
Info from: www.thebump.com and Sex Ed packet -
weeks 17-19
At week 17 the fetus is the size of an onion 5.1 in. 5 oz. Also at week 19 the fetus is the size of a mango 6 in. 8.5 oz. at this stage the fetus is know able to hear and can make sucking motion with mouth and tongue.
Info from: www.thebump.com and www.livestrong.com -
week 20
At week 20 the fetus is the size of a banana 6-7 in. 10-12 oz. The fetus is now large enough to fill the amniotic sac, the mother's heart beat is louder, lanugo covers entire body, fetus heartbeat can now be felt whith a stethoscope, nails appear, eyebrows and lashes appear.
Info from: www.livestrong.com -
week 24
Now at week 24 the fetus is now the size of a canteloupe 9 in. 1.5-2 ib. Air sacs now are formed in the lungs, and footprints and fingerprints.
Info from: www.thebump.com and Sex Ed packet -
weeks 25-28
By 28 weeks, the fetus could survive, with difficulty, outside the uterus. The lungs of the fetus are increasing in strength.
Info from: Langman's Medical Embryology; Fifth Edition -
weeks 29-32
By weeks 28-32, the fetus can suck its thumb. Also, the fetus can blink. Finally, the fetus will close its eyes during multiple periods of sleep.
Info from: www.livestrong.com -
week 36
Week 36 is when the fetus is the size of a honeydew 12 in. 4.5-6 ib. At this stage the lanugo begins to shed, and the nails are fully developed.
Info from: www.thebump.com and www.livestrong.com -
weeks 37-40
The fetus is now considered as full term. But at week 37 the fetus is the size of a winter melon 18.9-20.9 in. 6.2-9.2 ib. And at 40 weeks it is the size of a jackfruit. The bones grow larger and stronger, and brain contines to develop, the fetus grows about a pound, hair is thicker, organs grow stronger, birth of the fetus occurs between weeks 38 and 42.
Info from: www.thebump.com
