After conception, child development starts with the formation of the amniotic sac and the placenta, according to the Cleveland Clinic. In the first month, the embryo grows to 1/4 inch long, forms blood cells and begins circulation. Organs and extremities grow during the second and third month. The nervous system begins functioning during the fourth month, and the baby starts moving during the fifth month. Month six brings responses to sound, and development completes during the seventh through ninth months.Continue Reading
Six months after conception, most babies develop complete systems and can survive outside of the womb, states the Cleveland Clinic. During the seventh month, the baby has full hearing and begins to build fat stores. Month eight brings increased brain development and increased body movements. In the ninth month, the baby completes lung development and experiences coordinated movements.
Nine weeks after conception, the baby transitions from an embryo to a fetus, asserts Parents.com. The second trimester starts at 13 weeks; at this point, the fetus' body has begun growth of all internal organs. Most babies can also hear by 13 weeks. Around the 22-week mark, the baby's genitalia is developed enough for gender identification. During weeks 26 to 30, or the third trimester, the baby can blink and breathe.Learn more about Pregnancy