FETAL DEVELOPMENT

MONTH	CHARACTERISTICS
1	Fertilization/Conception egg (23 chromosomes) and sperm (23 chromosomes) unite creating a Zygote (46 chromosomes or 23 pairs) Zygote undergoes rapid cell division and becomes a mass of cells called Blastocyte Blastocyte travels through fallopian tubes and implants into uterus 7-10 days after fertilization and is called Embryo Embryo by the end of the month is the size of a grain of rice
2	Embryo – divides into 3 layers Ectoderm develops into brain, nerves, skin, hand, nails, tooth, enamel Mesoderm develops into bones, muscles, blood, heart, kidneys, reproductive system, part of lungs Endoderm develops into part of lungs, liver, intestines, urinary tract Week 5 -Embryo develops a head and tail Week 6 -Fetal heartbeat -Sonographic evidence of fetus - Week 7 -Tiny hands and feet start to develop -Tongue , teeth and eyelids start to form -Umbilical cord developed -Eyelids begin to fuse
3	Week 12 weeks Fetal heart rate can be detected by Doppler Tail disappears, reproductive system forming Eyelids, earlobes, limbs, digits continue to form Weight- 1 ounce Height- 3 inches
4	Week 16 Fetus can hear The fetal skin is transparent Major organs complete Swallows, kicks Weight- 6 ounces or approximately 1,200 g Height- 7 inches
5	Week 20 Mother-Quickening Non-electronic device (fetoscope) Lanugo, vernix caseosa develops Sucks thumb Meconium forming
6	Week 24 Heartbeat heard with Stethoscope Bones become harder Reacts to noises Facial features more recognizable Weight- 1.5-2 lbs Height- 10-13 inches
7	Week28 Brain sections form for distinct functions Protective fats, tastebuds develop Able to blink, eyes remain open for short periods Testicles move to groin (males) Weight- 2.5-3.5 lbs or 2500g Height- 11-16 inches
8	Week 32 Brains develops rapidly All organs except lungs mature Skin starts to smoothen Fingernails grow past fingertips Limited room for movement-settle into head down position Weight- 4-6 lbs Height- 16-18 inches
9	Week 36 Lungs mature L/S ratio 2:1 The skin is pink and the body is rounded Assumes birth position-Lightening may occur Vernix caseosa and Lanugo begin to disappear Labor begins Weight- 6-8 lbs or 2,500g Height- 20-22 inches or average 42-48 cm