-
Period: to
Week 1
First day of menstrual bleeding is considered first day of pregnancy and beginning of first trimester. The weeks of pregnancy are calculated from this date on out. -
Period: to
Week 2
Sperm cells make their way to the uterine tube for fertilization. Once the sperm gets to the egg, it joins to form a zygote- the first cell of a new individual. -
Period: to
Week 3
During this time the fertilized egg begins dividing. The gender is determined from male chromosome. -
Period: to
Week 4
Fertilized egg is now known as a blastocyst- fluid filled cluster of 50-60 cells. hCG is released into bloodstream after blastocyst is implanted to increase physical pregnancy signs. -
Period: to
Week 5
Embryo doubles in size. Placenta starts developing to deliver the embryo nutrition and oxygen. -
Period: to
Week 6
First blood cells and blood vessels develop. The heart is formed and begins beating. Brain develops into 5 parts. -
Period: to
Week 7
Heart beats with 1 chamber. Arms and legs begin to grow, jaw and vocal vords begin to form. The lungs, liver, thyroid gland and pancreas begin forming. -
Period: to
Week 8
Place where elbows and toes begin forming. Stomach is being made and face is taking shape. -
Period: to
Week 9
Nose tip, tongue, and larynx begin to form. The heart is complete. -
Period: to
Week 10
Embryo becomes a fetus the size of a strawberry. The baby's fingerprints are formed, and the nipples and hair follicles begin to form. -
Period: to
Week 11
At this point the fingers and toes are completely separated, and the baby can stick out it's tongue and swallow. The baby's body is sensitive to touch. (If the gender is male, the testicles start producing testosterone). -
Period: to
Week 12
The baby's face begins to actually look like a baby face and they begin moving a lot. The pancreas produces insulin and the fingernails and toenails grow. -
Period: to
Week 13
Bone starts replacing cartilage during this week. The external genitalia are almost defined. -
Period: to
Week 14
The beginning of the second trimester. For boys, their prostate gland is developing, and for girls her ovaries are moving down into the pelvis. -
Period: to
Week 15
The baby is able to move it's arms and make a fist. The body is unproportional and the baby's skull is still developing. -
Period: to
Week 16
During this week fat begins to form under the skin. The baby can also hear external voices, and sleeps and dreams. -
Period: to
Week 17
The baby's eyes are becoming sensitive to light and the fat begins to store underneath the baby's skin. -
Period: to
Week 18
The baby can hear sounds and may be startled. The baby also recognizes it's sleeping schedule. -
Period: to
Week 19
Females have all of their eggs at this point. The baby's genitals are distinct and the baby's hair begins to grow. -
Period: to
Week 20
The baby reacts to loud sounds and can recognize the mother's voice. Each of the five senses are developing. -
Period: to
Week 21
The baby's bone marrow has begun making blood cells and it's small instetine has started absorbing sugar. -
Period: to
Week 22
The baby is affected by the mother's movements. Taste buds begin forming on it's tongue and it's eyebrows and eyelids are fully developed. -
Period: to
Week 23
The baby can turn from side to side and head over heels. The inner ear is fully developed, which controls the sense of balance. -
Period: to
Week 24
The lungs are developing respiratory branches. The baby looks more and more like a newborn. -
Period: to
Week 25
During week 25, brain cells are almost mature and the brain is growing quickly. The baby is able to make a fist and hold onto objects. -
Period: to
Week 26
The baby begins to suck on it's thumb during this week. The brain can respond to touch and the baby's eyes will begin opening and closing. -
Period: to
Week 27
Week 27 is the beginning of the third trimester. The baby is recognizing the mother's voice, and other sounds. The baby has eyebrows and eyelashes and will look very similar at birth. -
Period: to
Week 28
The branches of the lungs are almost fully developed. The baby begins REM sleep and really recognizes the mother's voice. -
Period: to
Week 29
The baby's brain is developing neaurons. The baby's tastebuds taste and the baby can respond to pain. The babby can also distinguish real sounds and voices. -
Period: to
Week 30
The baby's red blood cells start transporting oxygen and getting rid of waste. The baby's skin is becoming smoother and it's hair is becoming fuller. -
Period: to
Week 31
The baby will react to loud noises and music. They can also detect light and darkness. -
Period: to
Week 32
The baby sleeps more throughout the day so it's movement is minimal. If the baby is a boy his testicles are moving towards his scrotum, and if it's a girl her clitoris is prominent. -
Period: to
Week 33
The baby is practicing breathing by inhaling amniotic fluid. The baby is also drinking and peeing out the same amount of amniotic fluid daily. -
Period: to
Week 34
During this week the baby may have turned it'd head downwards. The arms and legs are gaining more fat and the baby is developing immunities to mild infenctions. -
Period: to
Week 35
The mother should feel movement from the baby everyday, they reflex to light, sounds, and touch. -
Period: to
Week 36
During this week, the baby may drop into the birthing canal in experienced mothers. The baby fully recognizes the mother's voice and reacts to loud sounds. -
Period: to
Week 37
The mother's water can break anytime. The baby is still rapidly growing, the baby can weigh up to 7 pounds. -
Period: to
Week 38
The development of the baby is complete. The baby continues to store fat. It is in it's final birth position. -
Period: to
Week 39
The baby will continue to kick and punch. The baby is about 7 pounds and about 20 inches long. -
Period: to
Week 40
All systems are developed. The baby is settling into fetal position with it's head down ready to come out.