The egg and sperm unite and form a single living cell, a new human being.
This cell is smaller than a grain of salt, yet it contains detailed genetic information like the color of their hair and eyes, the unique fingerprint, the skin tone, the physical appearance and much more.
The heart, which is the size of a poppy seed, begins to beat.
The brain and every single organ system has started developing.
All four chambers of the heart are present and pumping the embryo's own blood to their brain and body.
The head, as well as the chest and abdominal cavities have formed.
The beginnings of the arms and legs are easily seen.
The baby has made dramatic progress in growth.
They are about 2/3 of an inch long from head to bottom.
Brain waves have been measured and recorded before eight and a half weeks of pregnancy.
The testicles or ovaries are beginning to form.
Lungs are developing and eyelids are forming.
The baby moves reflexively.
Breathing motions begin.
Kidneys begin to produce and release urine.
Several hundred muscles have formed and are present.
The hands and feet move frequently and the first signs of right or left handedness can be observed.
The baby is now two inches long and can yawn and suck.
The intestines are developing.
If the baby is a boy, he begins to produce the male hormone testosterone.
During the next several weeks they will grow rapidly.
The baby measures about three inches from head to heel.
Fingerprints start forming while fingernails and toenails begin to grow.
The bones are hardening in most locations.
The lips and nose are fully formed.
The baby can make complex facial expressions.
Measures about five inches from head to heel.
Taste buds are present.
Arms reach final proportion to body size.
The entire unborn baby responds to light touch, except for parts of the scalp.
Teeth are developing within the jawbones.
The mother may begin to feel fetal movement.
The heart beats between 120-180 times per minute and pumps about twenty five quarts of blood each day.
If she is a girl, millions of eggs are forming in her ovaries.
The baby is almost seven inches head to heel now.
Unborn baby girls move their jaws more often than boys.
The pregnancy is about halfway through.
The mother is usually showing at this point.
The baby has their own waking and sleeping patterns and even its own favorite sleeping position.
The baby can recognize its mother's voice.
The baby may have a blink-startle response to sudden sound near the mother's abdomen.
The baby is now about fifteen inches and weighs about two and a half pounds.
They will continue to gain weight, and the skin becomes smoother and less wrinkled.
Eyelashes and eyebrows are well-formed and the hair on the head is growing longer.
The baby now has a plump body and a firm grasp.
They are now around twenty inches long and weigh about seven to eight pounds.
The baby is ready to be born!
(Only four percent of babies are born on their due date)