·­» The Growth and Development of a Baby «­·

1st Month

After the sperm and egg combined, your newly created baby began a process of cell division that could rightly be called “explosive.” In these first four weeks, before some women even realize they are pregnant, your baby has begun to develop everything it needs to survive until birth. The fertilized egg will create your baby, the placenta, the amniotic sac and the amniotic fluid.

The creation of your baby begins before he is even attached to your uterine lining. As the egg divides and grows, cells begin to be specialized. Approximately 10 days after fertilization, your baby implants in the uterus. The lungs, heart and spinal cord begin to form. By the third week of life your baby ’s heart is already pumping blood on its own.

2nd Month

Baby continues to develop internal organs and other major structures of the body. By the end of the eighth week, all the organs are present. There is also continued growth and development of the brain and spinal column.

The arms and legs begin as small buds off the body, begin to lengthen. At the end of the arms and legs, tiny finger and toe buds begin to form. Even at this early stage, your baby already has individual fingerprints.

Your baby’s eyes and ears are beginning to form, although he will not be able to see or hear until later. If you could see into his gums you would find that tooth buds are beginning to appear.

3rd Month

Baby will be recognizable as a human. The face is formed, complete with 32 permanent teeth buds. There are even nails at the end of the fingers and toes. The genital organs are still forming, so you are not likely to be able to distinguish the sex yet.

Cartilage bones are forming rapidly, and the muscles have already begun to be laid down. Your baby will even move as the brain, nerves and muscles begin to function. However, baby’s small size makes his movements undetectable.

Your baby has a sucking reflex already in place, and may suck on his thumb or fist. He is also practicing swallowing the amniotic fluid, and at this point is able to excrete it as urine.

4th Month

As your baby’s ear bones begin to harden this month, he may begin to hear some sounds. Hearing will not be complete until the seventh month. The lungs also continue development, and as a part of that you baby will “breathe” amniotic fluid.

His face, right down to the external ears will be well developed. He can frown, squint and grimace. Although he cannot see yet, his retinas are becoming sensitive to light. Eyebrows and scalp hair are beginning to appear. He can even suck his thumb.

At the end of the sixteenth week your baby will be around 5.5 inches from crown to rump and weigh 6 oz, and baby is now big enough that his heartbeat can be heard with a regular stethoscope.

5th Month

Your baby’s senses are beginning to activate. His skin is sensitive to touch, he is beginning to taste, he may respond to some sounds and his eyesight continues to develop.

Along with the development of the internal organs, your baby has developed some protections for the uterine environment. Downy hairs called Lanugo hair have grown on his skin which may help hold the vernix in place as well as help regulate his temperature.

He has a primitive immune system, which does offer him limited protection from infection and illness. He is also developing a special type of fat called “Brown Fat” which helps him regulate his temperature. Deposits of brown fat will continue until he is born, at which time the fat will begin to dissolve.

At the end of the 20th week your baby will be around 7.5 inches from crown to rump and weigh 1 pound, and baby’s kidney’s are now functioning well enough that they can make urine.

6th Month

Baby’s skin has become opaque (it had been see-through), but it is still immature. The retina of the eye continues to form, but that also is not mature yet. The circulation to the lungs is forming, and the lungs are beginning to develop surfactant, however the lungs will be one of the last parts of your baby to fully mature.

His body has caught up with his head, and although the head is still large compared to an adult, your baby’s body and head are in the right proportions for a newborn. His brainwaves also resemble those of a full-term newborn. He is developing a sleep-wake pattern and may be developing an active time that is pretty regular from day to day.

At the end of the 24th week your baby will be around 10 inches from crown to rump and weigh 2 pounds.

7th Month

Your baby is growing fast, and space is getting tight. He may wiggle if he gets uncomfortable. As he becomes more oriented in space, he may move to a head down position.

Your baby can see, although the view from the uterus looks mostly like a dull glow when it is bright and just black when it is dark.

He can also hear, although most sounds are muffled. He is already becoming accustomed to mommy and daddy’s voices, as well as the sounds that are familiar where you live. He is learning to feel comfortable with the music you listen too, other people you live with, pet noises and regular life around you.

He can also taste, although the flavors of the amniotic fluid are subtle. What you eat can change the flavor of the amniotic fluid, so he is already becoming accustomed to the types of food you eat.

His lungs are preparing for breathing, and his movements give his muscles exercise. There is tremendous brain and nervous system growth taking place this month. He is also beginning to be able to have some ability to regulate his body temperature. His bone marrow is now fully responsible for making his blood, and he passes about 1 pint of urine every day. The fat developing under his skin helps to smooth out the wrinkles as it gives him energy stores for the first few days of life.

8th Month

Time of rapid growth for your baby, especially brain growth, so be sure you are eating well. He will gain at least two pounds before the end of this month. His tight fit in the uterus may cause him to slow down his movements a bit.

His lungs are still developing, but the rest of his body is pretty well formed. Even his eyes are functioning, able to focus and he even blinks. You may even be able to recognize his periods of sleep and wake.

The umbilical cord is coated in a gelatinous substance, so even though he likes to twist and turn, the cord is protected from kinks and knots.

9th Month 

  Your baby is practically ready to be born. A few last details to give him a great start in the world beyond your womb and he’s on his way.

  In this ninth month, your baby’s biggest job is to continue to put on weight. He needs this extra weight to supply his energy demands during the first few days while he is waiting for your milk to come in. He is also working getting his lungs fully mature.

  His downy hairs are being shed, and the vernix is wearing off his skin. The more lanugo hair and vernix a baby has at birth, the younger his gestational age. He may have long nails that need to be clipped right away. His eyes do have color, but it may change within the next six months.

  His immune system is still immature, so he is receiving antibodies through the placenta, and after he is born he will get antibodies through your colostrum and milk.

  At the end of the 38th week your baby will be around 14-15 inches from crown to rump and weigh about 6-8 pounds.