Fetal development is the stage of forming the various organs of the fetus, followed by the stage of increasing the size and developing those organs to become larger and more complete.
- Month 1: Development of the central nervous system into the brain and spinal cord
- Month 2: Fetus size 2.5 cm, large head, limbs as small buds, heartbeat clearly detected
- Month 3: Length 9 cm, head still large compared to the body, limbs clear, can swing arms and stretch legs, heart fully developed
- Month 4: Length 16 cm, weight about 100 grams, almost all organ systems developed, genital organs complete but not clearly visible by ultrasound
- Month 5: Length 23-30 cm, weight about 300 grams, hair on the scalp but eyelids still closed, baby kicks, pushes, and turns around, first-time mothers begin to feel these movements
- Month 6: Length about 30-35 cm, weight 600 grams, lungs begin to function, eyelids start to open, begins to hear sounds, fingerprints and toe prints present
- Month 7: Length 35-40 cm, weight about 1,000 grams, skin moist because sebaceous glands under the skin start to function
- Month 8: Body length 40-45 cm, weight about 1,600 grams, lungs function better, skin pinkish-red but still wrinkled due to low fat
- Month 9: Baby size about 45-50 cm, this is the period of full growth, skin smooth, vernix caseosa covering the baby decreases, lungs fully functional
