Entire pregnancy days – 266 – 280 days 37 – 42 weeks
Differentiation of Primary Germ layers
* Endoderm
1st week endoderm – primary germ layer
Thyroid – for basal metabolism
Parathyroid - for calcium
Thymus – development of immunity
Liver – lining of upper RT & GIT
* Mesoderm – development of heart, musculoskeletal system, kidneys and repro organ
* Ectoderm – development of brain, skin and senses, hair, nails, mucus membrane or anus & mouth
First trimester:
1st month - Brain & heart development
GIT& resp Tract – remains as single tube
1. Fetal heart tone begins – heart is the oldest part of the body
2. CNS develops – dizziness of mom due to hypoglycemic effect
Food of brain – glucose complex CHO – pregnant womans food (potato)
Second Month
1. All vital organs formed, placenta developed
2. Corpus luteum – source of estrogen & progesterone of infant – life span – end of 2nd month
3. Sex organ formed
4. Meconium is formed
Third Month
1. Kidneys functional
2. Buds of milk teeth appear
3. Fetal heart tone heard – Doppler – 10 – 12 weeks
4. Sex is distinguishable
Second Trimester: FOCUS – length of fetus
Fourth Month
- lanugo begins to appear
- fetal heart tone heard fetoscope, 18 – 20 weeks
- buds of permanent teeth appear
Fifth Month
1. lanugo covers body
2. actively swallows amniotic fluid
3. 19 – 25 cm fetus,
4. Quickening- 1st fetal movement. 18- 20 weeks primi, 16- 18 wks – multi
5. fetal heart tone heard with or without instrument
Sixth Month
1. eyelids open
2. wrinkled skin
3. vernix caseosa present
Third trimester: Period of most rapid growth. FOCUS: weight of fetus
Seventh Month – development of surfactant – lecithin
Eighth Month
1. lanugo begin to disappear
2. sub Q fats deposit
3. Nails extend to fingers
Ninth Month
1. lanugo & vernix caseosa completely disappear
2. Amniotic fluid decreases
Tenth Month – bone ossification of fetal skull
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