Day 1: Conception: A new member of the human species begins. The zygote has a complete and unique set of 46 chromosomes (23 from each parent), the entire genetic blueprint. She needs only a suitable environment and nutrition in order to develop herself through the different stages of human life.

Day 10: The new baby burrows in and attaches securely to the wall of her mom's womb.

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Day 17: Blood vessels have developed.

Day 19: The foundations for her brain, spine, and nervous system are laid. Eyes start to develop.

Day 21: Her precious heart now beats 70 times per minute.

Day 30: Budding arms and legs emerge and her beautiful face begins to appear.

6 weeks: The skeleton is complete and reflexes are present. The child has measurable brain waves.

7 weeks: The baby has the appearance of a tiny infant, with fingers, toes, and ears.

8 weeks: All organs are functioning — stomach, liver, kidney, brain—and all systems are intact.

9-10 weeks: The baby squints, swallows, and retracts her tongue.

11-12 weeks: The baby sucks her thumb and inhales.

16 weeks: The mother may begin to feel her child’s movements. The baby grasps with hands, swims, kicks, and turns somersaults

18 weeks: The vocal cords are working.

20 weeks: She can experience as much pain as an adult. In the fifth and sixth months, the child responds to outside stimuli, including music and voices.

22 weeks: Babies today are usually capable of surviving outside the womb (with assistance) at 22 weeks post-conception (24 weeks from the last menstrual period). They can often survive even earlier. This is called viability.

38 weeks: The unborn child dramatically increases in size and weight during the second half of pregnancy until birth at about 38 weeks (40 weeks from the last menstrual period).

Birth, of course, is not the end of human development. The baby continues to grow and develop in the months, years, and decades to follow. The life of every human being is a continuum beginning at conception and proceeding (if all goes well) through the embryonic, fetal, infant, child, adolescent, and adult stages.