The organ formation stage of the fetus occurs during the first 4 months of pregnancy. After that, it is the stage of growth and development of 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, arms and legs are small buds, heartbeat is clear
- Month 3 Length 9 cm, head still large compared to the body, arms and legs are clear, can swing arms and stretch legs, heart fully developed
- Month 4 Length 16 cm, weight about 100 grams, almost all organs are developed, genital organs are 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, starts to kick, push, and turn around, first-time mothers begin to feel 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 appear
- Month 7 Length 35-40 cm, weight about 1,000 grams, skin is moist as sebaceous glands under the skin start to work
- Month 8 Body length 40-45 cm, weight about 1,600 grams, lungs function better, skin is pinkish-red but still wrinkled due to little fat
- Month 9 Length about 45-50 cm, the fetus is fully grown, skin is smooth, vernix caseosa covering the baby decreases, lungs function fully
