The development of a fetus occurs in stages, beginning with the formation of various organs within the first four months of pregnancy. After this initial phase, the organs increase in size and continue to develop towards completion.
- Month 1: The central nervous system begins to form, developing into the brain and spinal cord.
- Month 2: The fetus is about 2.5 cm in size. The head is large, with small buds forming into arms and legs. The heartbeat becomes clear and detectable.
- Month 3: The fetus grows to 9 cm. The head remains large compared to the body, but the arms and legs are more distinct, allowing for arm movements and leg stretching. The heart is fully developed.
- Month 4: The fetus is approximately 16 cm long and weighs around 100 grams. Almost all organ systems have developed. The sex organs are formed but may not be clearly visible through ultrasound.
- Month 5: The fetus measures between 23-30 cm in length and weighs about 300 grams. Hair begins to grow on the scalp, but the eyelids remain closed. The fetus starts kicking, turning, and moving, which first-time mothers may begin to feel.
- Month 6: The fetus is around 30-35 cm long and weighs 600 grams. The lungs start functioning, the eyelids begin to open, the fetus can hear sounds, and fingerprints and toe prints form.
- Month 7: The fetus grows to 35-40 cm in length and weighs about 1,000 grams. The skin becomes moist as the sebaceous glands start working.
- Month 8: The body length reaches 40-45 cm, and the fetus weighs around 1,600 grams. The lungs improve in functionality, the skin turns pinkish-red, but remains wrinkled due to low fat content.
- Month 9: The fetus measures approximately 45-50 cm in length. At this stage, the fetus is fully developed, with smooth skin and reduced white protective coating (vernix caseosa). The lungs are completely functional.
