Fetal Development

Timeline of Fetal Development:

Day 1 - conception takes place.
7 days - tiny human implants in mother’s uterus.
10 days - mother’s menses stop.
18 days - heart begins to beat.
21 days - pumps own blood through separate closed circulatory system with own blood type.
28 days - eye, ear and respiratory system begin to form.
42 days - brain waves recorded, skeleton complete, reflexes present.
7 weeks - photo of thumbsucking.
8 weeks - all body systems present.
9 weeks - squints, swallows, moves tongue, makes fist.
11 weeks - spontaneous breathing movements, has fingernails, all body systems working.
12 weeks - weighs one ounce.
16 weeks - genital organs clearly differentiated, grasps with hands, swims, kicks, turns, somersaults, (still not felt by the mother.)
18 weeks - vocal cords work – can cry.
20 weeks - has hair on head, weighs one pound, 12 inches long.
23 weeks - 15% chance of viability outside of womb if birth premature.*
24 weeks - 56% of babies survive premature birth.*
25 weeks - 79% of babies survive premature birth.*

(*Source: M. Allen et. al., "The Limits of Viability." New England Journal of Medicine. 11/25/93: Vol. 329, No. 22, p. 1597.)