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Pregnancy and Fetal Development

Picture of First Trimester (4 Weeks)

Picture of First Trimester (4 Weeks)
At 4 weeks gestational age, a baby in the first trimester starts to grow a brain, spinal cord, and heart. Arm and leg buds begin to form. The baby is considered an embryo at this point and is 1/25 of an inch long.
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Text Reference: American Pregnancy Association: "Fetal Development"