Week 2 (Apr. 24): At the end of week two, fertilization occurs and a unique, complete human being with 46 chromosomes detailing her entire development throughout life has entered the world!

Week 3 (May 1): The baby’s cells are dividing and growing rapidly as she travels down the fallopian tube to implant in the wall of the womb so mother can nourish the developing child.

Week 4 (May 8): The baby is the size of a period at the end of a sentence, and cells in the baby have separated off to form the placenta which will nourish the child until birth. The baby has already communicated to her mother’s body with hormones to let her know she is growing in the womb.

Week 5 (May 15): Organ systems are beginning to develop and the baby’s heart starts to beat, just 21 days after fertilization.

Week 6 (May 22): The baby’s neural tube closes, eventually becoming the fully-formed brain and spinal cord. The baby’s tiny heart is already pumping blood and beats 80 times a minute, and she is 1/8 of an inch long.

Week 7 (May 29): Tiny nostrils are visible and the baby’s hands and feet are beginning to take shape.

Week 8 (June 5): The baby is 1/2 of an inch long. Only six weeks after coming into existence fingers, ears and eyes can be seen. Taste buds are forming on her tongue and tooth buds are taking shape.

Week 9 (June 12): The baby has grown a quarter of an inch in just a week and her teeny tiny toes are now visible.

Week 10 (June 19): The baby’s eyelids close to protect the wonderfully complex eyes while they form. Each minute the baby’s brain develops 250,000 new neurons and she can now move her muscles.

Week 11 (June 26): The baby is two inches long. She has reached the end of the embryonic stage and is now known as a “fetus,” Latin for “young one.” Her kidneys are developing and produce urine for the first time.

Week 12 (July 3): Fingernails have begun forming on the baby’s small fingers.

Week 13 (July 10): Bones are beginning to harden in the baby’s head, arms and legs.

Week 14 (July 17): The baby is 3 1/2 inches long and if we had a window to the womb we could tell if she was a girl or if he was a boy.

Week 15 (July 24): The baby’s hair pattern on her head is forming. Researchers argue whether her widow’s peak is the result of her genetic code or her own self-directed growth in the womb.

Week 16 (July 31): An ultrasound at this point would reveal the baby moving her legs and arms and maybe even sucking her thumb. It might also be able to determine her gender.

Week 17 (Aug. 7): Fat begins to form to keep the baby warm and cozy after birth.

Week 18 (Aug. 14): The baby is 5 1/2 inches long and might hear her first sound with her developing ears.

Week 19 (Aug. 21): A waxy substance called vernix begins to cover the baby’s skin to protect it from the amniotic fluid

Week 20 (Aug. 28): Halfway through 40 weeks, the baby’s mother might begin to feel her tiny movements for the first time.

Week 21 (Sept. 4): The baby is now 10 inches long. Her digestive system is getting exercise as she swallows amniotic fluid.

Week 22 (Sept. 11): Hair becomes visible. The baby’s eyebrows might even be visible and her body is covered in small, fine hairs called lanugo to help hold the protective vernix to her skin.

Week 23 (Sept. 18): We could take the baby’s fingerprints and rapid eye movements start occurring. Is the baby dreaming, and what does a baby in the womb dream about?

Week 24 (Sep. 25): The baby is 8 inches long and has been regularly sleeping and waking. Her mother might be able to guess which she is doing based on her movement.

Week 25 (Oct. 2): Her mother’s voice or other familiar sounds are recognized by the baby, who responds to them.

Week 26 (Oct. 9): Lungs are getting stronger in the baby who is 9 inches long now. Her teeth buds are apparent in her gums.

Week 27 (Oct. 16): The baby has reached the end of the second trimester. Every major body system is present and has been functioning, and only 13 more weeks of exercise in the womb are needed to make her ready for the wide world.

Week 28 (Oct. 23): Eyelids have reopened and the baby’s eyelashes are present.

Week 29 (Oct. 30): The baby’s bones have finished forming, though they are soft in preparation for continued growth.

Week 30 (Nov. 6): The baby’s eyes are wide open now and she has a full head of hair.

Week 31 (Nov. 13): The baby’s brain has developed enough to control breathing and her own body temperature independent of mother.

Week 32 (Nov. 20): The baby’s first haircut happens as lanugo begins to fall off.

Week 33 (Nov. 27): Small pupils in the baby’s eyes can function, dilating and constricting in dim or bright light.

Week 34 (Dec. 4): Fingernails have now fully grown out on her fingers as the baby reaches more than a foot and a half in length.

Week 35 (Dec. 11): In preparation for birth, the baby begins to gain lots of weight, about a half a pound every week.

Week 36 (Dec. 18): The baby is getting quite cramped in the womb now, but she is still able to move around. What a big change the next month will bring!

Week 37 (Dec. 25): Almost ready for birth, the baby begins positioning head down in the womb to make birth easier.

Week 38 (Jan. 1): The baby has a firm grasp with her hands and is considered full-term at this point.

Week 39 (Jan. 8): While she continues growing in the womb, the baby’s family is anxiously waiting and preparing for the moment they can see her with their own eyes for the first time.