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Fertilization
The sperm and egg unite as one. -
Period: to
Trimester Pregnancy
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First Trimester Begins
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Week 1
It begins when an egg leaves the ovary and travels into the fallopian tubes, where it’s met by sperm and fertilized. From there the fertilized egg travels through the fallopian tubes and into the uterus, where implantation occurs. -
Week 2
During this time of transformation, the embryo simply floats within the uterus, protected by the secretions of the uterus lining. The baby is still very, very small — only .1 to .2 mm long. -
Week 3
Specific parts of the baby are beginning to take shape. Features such as gender and eye, hair, and skin color have already been determined, and the brain, head, spinal cord, and gastrointestinal tract are developing. The heart starts beating, and the size of the baby varies from .2 mm to .5 mm. -
Week 4
The ball of cells is splitting into the embryo (your future child) and placenta. -
Week 5
Looks like a small tadpole and is starting to form major organs (heart, stomach, liver, kidney) and systems (digestive, circulatory, nervous). -
Week 6
Starting to sprout a nose, eyes, ears, chin and cheeks. -
Week 7
Its generating about one hundred new brain cells each minute.
Not only is its brain becoming more complex, but its heart is too.
Its developing a permanent set of kidneys and her arm and lef joints are now forming. -
Week 8
Its fingers and toes are now only slightly webbed, and its tail is gone. -
Week 10
Baby has working arm joints, and its cartilage and bones are forming.
Its vital organs are fully developed and they're starting to function.
Its fingernails and hair are starting to appear. -
Week 11
Its fingers and toes aren't webbed anymore.
Tooth buds, hair follicles and nail beds are forming. -
Week 12
About to enter the growth and maturation stage, in which her organs and tissues will grow and develop rapidly. -
Week 13
Intestines are moving from the umbilical cord to their more permanent place, in her tummy. -
First Trimester Ends
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Week 14
Its kidneys are making urine, and its liver and spleen are doing their jobs.
And its growing lanugo, a thin, peach-fuzz-like hair, all over its body. -
Second Trimester Begins
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Week 15
Joints and limbs can all move. -
Week 16
Listening to voices. -
Week 17
Its rubbery cartilage is now turning to bone.
And its growing some meat on those bones.
Its growing a stronger, thicker umbilical cord. -
Week 18
If you are having a little girl, her fallopian tubes and uterus have positioned themselves into the correct place. If you are having a little boy, then his genitals may be noticed on your next ultrasound. -
Week 19
The arms and legs are now proportional to the body, the scalp produces hair, and the skin is now covered with fine hair and a creamy material called vernix that protects it. The baby’s hearing is almost fully developed too. If your baby is a girl, at this point in her life her ovaries have more than 6 million eggs. -
Week 20
At 11 ounces and a little more than 7 ½ inches long, your baby’s growth has slowed in recent weeks, but it will begin to accelerate again from the twentieth week forward. You’re probably feeling your baby’s movements more frequently as he or she tests the boundaries within the walls of the womb. -
Week 21
The eyebrows and eyelids are fully developed at this point, and the fingernails and toenails completely cover the tips of your baby’s fingers. -
Week 22
The skin is still wrinkly and covered with lanugo, but the internal organs are growing fast and the eyelids and eyebrows are becoming distinguishable. Even the eyes have formed fully, but the irises (the colored part of your eye) still lack pigment. -
Week 23
Your baby is forming pigmentation at this stage, and as the fat develops, the skin remains loose, since skin is produced much more quickly than fat. You may also feel kicks and punches as your baby moves within the uterine walls. -
Week 24
With their eyes still shut, they use their hands and feet to maneuver and develop their sense of touch. The hair on the scalp is still growing at an even pace, and your baby is continuing to inhale amniotic fluid into its lungs as practice for breathing after birth. -
Week 25
During week 25, your baby starts to plump up as fat builds up under the skin. At this stage, most patients report feeling a LOT of fetal movement. -
Week 26
During the twenty-sixth week your baby’s eyelids begin to open and blink on their own. The eyes are blue, but this will often change after birth. The development of your baby’s eyes is almost complete, and although he or she still seems very lean, fat is definitely building underneath the skin and will continue to do so until birth. -
Second Trimester Ends
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Week 27
You may also feel your baby hiccuping as their lungs continue to mature and they inhale and exhale amniotic fluid. -
Third Trimester Begins
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Week 28
The eyes have opened, and the eyebrows and eyelids are fully formed, and even the eyelashes are now visible. The enzyme system and the endocrinological processes are still developing, and the lungs are still maturing as the third trimester begins. As your baby moves around, you may be feeling kicks and punches more frequently. -
Week 29
Your baby is continuing to grow, weighing close to three pounds and stretching to over a foot long. You may notice that this growth is causing increased hunger, as your baby uses most of the nutrients you consume to grow more. -
Week 30
His skin is getting smoother.
But his brain is getting wrinklier to make way for all that essential brain tissue.
He's now strong enough to grasp a finger! -
Week 31
He's going through major brain and nerve development.
Eye development, too. His irises now react to light!
All five of his senses are in working order. -
Week 32
You may notice that your baby seems much calmer these days. This is mainly due to the fact that there’s less room inside the womb. Most babies have their head down, whereas others have completely turned around and put themselves into the breech position. -
Week 33
He's keeping his eyes open while awake.
He's also starting to coordinate breathing with sucking and swallowing.
His bones are hardening.
And he going through major brain development. -
Week 34
The facial features are very distinct at this point. As the fat continues to build under the skin, your baby is looking a bit plumper and is taking on his or her mature facial characteristics. He or she will continue to grow as the due date approaches. You may notice too that he or she is still getting the hiccups. This is normal. -
Week 35
Your baby has reached an amazing 18 inches and weighs approximately six pounds by this point. Even though most of the development is complete, your baby will continue to plump up and put on weight. His or her liver is functioning and producing waste on its own, and the kidneys are also fully matured. You will continue to feel kicks as the space inside the amniotic sac continues to shrink. The baby’s ears are fully formed and functioning just fine, so talk to him or her as often as possible. The -
Week 36
At the thirty-sixth week, your baby has pretty much finished growing, although he or she will continue to build fat under the skin, causing the arms, legs, knees, cheeks, and face to plump more and more. He or she is one week away from being considered full term, at 19 inches in length and weighing around six pounds. -
Week 37
Your baby is growing at a much slower rate these days, about ½ ounce per day. Before, his or her skin was very loose and wrinkly. These days it’s becoming much smoother due to the fat building up under the skin. His or her lungs are well developed, and breathing movements are more frequent as the baby gets the hang of the inhale/exhale process. The amniotic fluid continues to decrease as your baby grows, and he or she weighs approximately 6½ to 7 pounds and is about 19 inches long by now. The ba -
Week 38
A major development during this 38th week is that the tear ducts begin to form. The gender can easily be identified now, as the sex organs have fully matured. Your baby is reacting to sounds, clenching his or her fists, and preparing for childbirth. -
Week 39
If your baby is born during this week, he or she will likely be healthy, and all organs will be able to function on their own. The lungs are mature by the 39th week, but they won’t function on their own until after birth. Your baby could weigh as much as seven pounds—or even a little more—if you give birth during this week. If you do not give birth this week, however, your baby will continue to grow. He or she should remain active until birth, so if there is a decrease in movement at this stage, -
Week 40
Your baby is now developing immunities that will be needed for survival after birth. At this point, if you have not given birth, your baby can weigh up to ten pounds and may be as long as 21 inches. All of his or her bones have hardened except for the skull, which remains soft for delivery. As he or she continues to move around in a small space, your pains may increase. -
Third Trimester Ends
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Birth
