-
Weeks 1-2
The mother is not actually pregnant yet. The sperm travels through the Fallopian tubes to fertilize an egg. -
Weeks 3-4
Conception occurs and the zygote turns into a blastocyst and travels back through the Fallopian tubes. The rapid cell division begins and the blastocyst implants in the uterus lining. This is now called an embryo. -
Weeks 5-6
In weeks 5-6, the neural tube closes and the brain and spinal cord form. The heart, eyes, ears, organs, bones, head, and trunk start to form. The arm and leg limb buds appear and the brain begins development. The baby is 1/6 of an inch long. -
Weeks 7-8
The brain and face shape grow and the lungs, fingers, and toes begin to form. The heart forms 4 chambers and the lips and nose have formed. The trunk and neck straighten The baby is 1/2 an inch long. -
Week 10
The head of the baby is half the size of the baby. All body parts are present and identifiable. The baby is 1 1/4 inches long. -
Week 11
The genitals of the baby develop and the teeth buds form. The baby is about 2 inches long and weighs about 1/3 of an ounce. -
Week 12
The fingernails grow and the face becomes more defined. The intestines are in the abdomen. The baby is 2 1/2 inches in length and 1/2 an ounce. -
Week 14
The baby's sex will become apparent and the baby can make urine and swallow. The baby is 3 1/2 inches in length and 1 1/2 ounces. -
Week 16
The baby is moving but the mom cannot yet feel it. The baby is about 4 1/2 inches and 4 ounces. -
Weeks 18-19
The baby begins to hear and the digestive system now works. The vernix caseosa covers the body. -
Weeks 20-21
The baby now has regular sleep and wake patterns. All organs and structures have formed. Breathing movements occur and the baby is covered in lanugo. The baby may begin to suck their thumb. The baby is about 6 1/3 inches in length and 11 ounces. -
Week 22
The baby now has nails, fingerprints, eyebrows, lashes, and hair. They are more active and the heartbeat can be heard with a stethoscope. They have the lowest limit of viability at this point. They are about 7 1/2 inches long and 1 pound. -
Week 24
The baby has wrinkly skin, is translucent, and pinkish red. Their lungs develop. They are about 8 inches and 1 1/3 pounds. -
Weeks 28-29
The eyes begin to partially open and close. The central nervous system directs breathing and body temperature control. Lungs are capable of breathing air and the baby kicks and stretches. They are now 10 inches and 2 1/4 pounds. -
Weeks 31-32
The baby has finished most major developments, Rapid weight growth begins and their lanugo starts to fall off. They are 11 inches and 3 3/4 pounds. -
Week 34
The baby responds to light and has a breathing motion. Their fingernails and toenails continue to grow. The skin is pink and smooth. They are 12 inches long and 4 1/2 pounds. -
Weeks 36-37
The baby takes up most of the amniotic sac and starts to turn head down for labor. They are 13 1/2 inches and 6 pounds. They now gain 1/2 a pound a week until delivery. -
Weeks 38-40
The brain, lungs, and liver are still developing. Brain will double in size between weeks 35 and 39. 39 weeks is the full term. Weight gain helps with temperature control once born.