Week 1 to 4

The first and second week of pregnancy, the woman is not actually pregnant. Pregnancy usually occurs two weeks after the start of the last menstrual period, and when pregnancy occurs, the period of the menstrual cycle is calculated from within the pregnancy,[1] Where the ovulation of the egg can occur in the uterus on the fifteenth day of the 28-day cycle, and ovulation can occur between the ninth day and the twenty-first day,[2] In the third week, the fetus is very small, the size of a pinhead, and it is a group of about 100 cells that multiply and grow rapidly, and then the outer layer forms the cells of the placenta, and the inner layer is the fetus, and the fertilized egg grows, and a water bag is formed around it, and it is filled Gradually with fluid, which is called the amniotic sac, and the placenta develops, which works to transfer nutrients from the mother to the child and transport its waste, and the first form of the fetus is formed in the form of dark and large circles of the eyes, the mouth, the lower jaw and throat develop, and blood cells are formed, The blood circulation begins to work, and at the end of the first month, the length of the fetus is about 0.635 centimeters.[3]

Fifth to eighth week

The heart, brain, spinal cord, muscles and bones of the fetus begin to develop, the placenta continues to nourish the child, the umbilical cord appears and connects the child to deliver blood to him, and in the sixth week, the eyes and limbs begin to form, and the fetal heartbeat can be heard using ultrasound,[4] In the seventh week, the hands and feet grow, and many parts continue to develop, such as: the heart, intestines, lungs, brain, spinal cord, nose, mouth, eyes, and in the eighth week, eyelid folds and ears are formed, fingers and toes are developed, and The nervous system is well formed, the digestive system and sensory organs begin to develop, and bone begins to replace cartilage.[5]

The ninth to twelfth week

It is the third month of pregnancy, and the hands, feet, and fingers are fully formed at this stage, and the fetus can open and close its mouth and hands, nails and external ears begin to form, and genitals are formed, but it is difficult to determine the sex of the fetus, and at the end of this period the fetus is complete, and its body organs begin And his limbs are growing, and the circulatory system, the urinary system, and the liver are working.[6]

Thirteenth to sixteenth week

The ovaries or testicles are fully developed inside the body, and the genitals are formed outside the body, and the weight of the fetus is about 25 grams, and in the fourteenth week, the length of the fetus is about 85 mm, and the child begins to swallow a little of the amniotic fluid that passes into the stomach, and the kidneys begin to work And the liquid comes out in the form of urine, but in the fifteenth week, the child begins to hear, he may hear a faint sound from the outside world, and any noise made by the digestive system, in addition to the mother’s voice, the sound of her heart, and the eyes begin to become sensitive to light, and in the sixteenth week the fetus can Moving his facial muscles, making expressions on him, the nervous system continues to develop, allowing the muscles in the fetus’s limbs to flex.[7]

The seventeenth to twentieth week

At the seventeenth week, the child grows rapidly, weighing about 150 grams, the face begins to appear more, eyelashes grow, his eyes move, lines are formed on the skin of the fingers, the fetus has its own fingerprints, the child has a strong hand grip, the fetus moves a little, and may respond To loud noises from the outside world, such as music, and by the 20th week, the baby’s skin is covered with a white, greasy substance, which helps protect the skin.[8]

week twenty-one to twenty-four

The weight of the fetus in the twenty-first week is about 350 grams, and the placenta continues to grow throughout the pregnancy, but not as fast as the fetus grows, and the fetus becomes covered with fine hair, and the child can be born in the twenty-fourth week, but is placed in the newborn care units Childbirth, due to incomplete lungs and other vital organs.[9]

Twenty-fifth to twenty-eighth week

The fetus begins to add some fat and grows more hair. In the sixteenth week, the fetus inhales small amounts of amniotic fluid, and can open and close its eyes, and suck its fingers.[10] The mother feels the movement and kicks of the fetus, and his heartbeat slows down to about 140 beats per minute, and his body continues to develop, and at the twenty-eighth week, the fetus weighs about 1 kilogram, and its heartbeat can be heard through a stethoscope.[11]

Twenty-ninth to thirty-second week

During this period, the movement of the fetus increases, the fetus continues to grow, the skin begins to appear less wrinkled and smoother, and the fatty layer covering the skin begins to disappear, and by the thirty-second week, the child is lying on his head, facing down, ready for birth, and the amount of The amniotic fluid is in the uterus, and the fetus continues to swallow the fluids, and excrete it in the form of urine.[12]

Thirty-third week to thirty-sixth week

The fetus’s brain and nervous system are fully developed and become more solid, but the skull bones remain soft, smooth and separated even after birth, to facilitate its passage through the birth canal, and in the thirty-sixth week the lungs are fully formed, ready to take the first breath after birth, and the digestive system Ready for milk. [13]

Week thirty-seven to forty

The fetus in this period weighs about 3-4 kilograms, and the intestines of the fetus contain meconium, the sticky green substance that will form the first stool after birth.[14]

the reviewer

  1. ↑ “Pregnancy week by week”, www.mayoclinic.org, 12-7-2017, Retrieved 13-5-2018. Edited.
  2. ↑ “Your pregnancy: 2 weeks”, www.babycenter.com, Retrieved 13-4-2018. Edited.
  3. ↑ Traci C. Johnson (21-6-2016), “Your Pregnancy Week by Week: Weeks 1-4”, www.webmd.com, Retrieved 13-5-2018. Edited.
  4. ↑ Traci C. Johnson (12-9-2016), “Your Pregnancy Week by Week: Weeks 5-8”, www.webmd.com, Retrieved 13-5-2018. Edited.
  5. ↑ Traci C. Johnson (12-9-2016), “Your Pregnancy Week by Week: Weeks 5-8”, www.webmd.com, Retrieved 5-15-2018. Edited.
  6. ↑ “Fetal Development: Stages of Growth”, www.my.clevelandclinic.org, Retrieved 5-13-2018. Edited.
  7. ↑ “You and your baby at 13-16 weeks pregnant”, www.nhs.uk,2-28-2017, Retrieved 13-5-2018. Edited.
  8. ↑ “You and your baby at 17-20 weeks pregnant”, www.nhs.uk, 31-3-2017, Retrieved 13-5-2018. Edited.
  9. ↑ “You and your baby at 21-24 weeks pregnant”, www.nhs.uk,2-28-2017, Retrieved 5-13-2018. Edited.
  10. ↑ “Pregnancy Week by Week”, www.babycenter.com, Retrieved 5-1-2018. Edited.
  11. ↑ “You and your baby at 25-28 weeks pregnant”, www.nhs.uk,2-28-2017, Retrieved 5-13-2018. Edited.
  12. ↑ “You and your baby at 21-24 weeks pregnant”, www.nhs.uk,2-28-2017, Retrieved 5-13-2018. Edited.
  13. ↑ “You and your baby at 33-36 weeks pregnant”, www.nhs.uk,2-28-2017, Retrieved 5-13-2018. Edited.
  14. ↑ “You and your baby at 37-40 weeks pregnant”, www.nhs.uk,2-28-2017, Retrieved 5-13-2018. Edited.

Fetal development stages in weeks