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How does a fetus change during the third month after conception?
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human development
Growth of the human fetus from the fourth month to the ninth month of pregnancy.
During the third month after conception, the developing organism—now referred to as a fetus—undergoes significant changes as it increasingly resembles a human being, though the head remains disproportionately large.1
Key developmental milestones during this period include:
- Physical Structure: The intestine, which previously protruded into the umbilical cord, returns into the abdomen.1
- Facial Features: The ears rise to the level of the eyes, and the eyelids fuse shut.1
- Skeletal and External Development: Nails begin to form, and ossification centers appear in most of the future bones. Additionally, the external genitalia become recognizable, allowing for the determination of sex.1
- Neurological Development: By the end of the third month, the main outlines of the brain are recognizable, following the differentiation of the neural tube into distinct regions.2
By the end of this month, the fetus typically reaches a crown-rump length of approximately 75 mm (3 inches) and weighs about 25 grams (1 ounce).1