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    Baby Development 1st Trimester Highlights

    A lot has happened in the past three months. Your baby is only 3 or 4 inches long, but already can open and close his fists and mouth. Fingernails and toenails are just beginning to develop. Already, your tiny baby has:

    • A brain, spinal cord, and flexible backbone.
    • Lungs that are not fully developed.
    • A heart that beats 120 to 160 beats per minute.
    • All major organs, but not fully developed.
    • A soft skeleton.
    • Eyes with eyelids that stay closed.
    • A nose, mouth, and chin.
    • Distinct fingers and toes and tiny fingernails.
    • Genitalia, not fully developed.
    • Little teeth buds.

    WebMD Medical Reference

    Reviewed by Traci C. Johnson, MD, FACOG on July 05, 2014

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