Skip to content

    Health & Pregnancy

    Font Size
    A
    A
    A

    The First Trimester: Your Baby's Growth and Development in Early Pregnancy

    Month One of Pregnancy

    The amniotic sac is a water-tight sac that forms around the fertilized egg. It helps cushion the growing embryo throughout pregnancy.

    The placenta also develops at this point in the first trimester. The placenta is a round, flat organ that transfers nutrients from the mother to the baby, and transfers waste from the baby.

    A primitive face takes form with large dark circles for eyes. The mouth, lower jaw, and throat are developing. Blood cells are taking shape, and circulation will begin.

    By the end of the first month of pregnancy, your baby is around 6-7mm (1/4 inch) long - about the size of a grain of rice!

    end of first month

    Month Two of Pregnancy

    Your baby's facial features continue to develop. Each ear begins as a little fold of skin at the side of the head. Tiny buds that eventually grow into arms and legs are forming. Fingers, toes, and eyes are also forming in the second month of pregnancy.

    The neural tube (brain, spinal cord, and other neural tissue of the central nervous system) is well formed. The digestive tract and sensory organs begin to develop. Bone starts to replace cartilage. The embryo begins to move, although the mother cannot yet feel it.

    By the end of the second month, your baby, now a fetus, is about 2.54cm (1 inch) long, weighs about 9.45g (1/3 ounce), and a third of baby is now made up of its head.

    6 Weeks

    Month Three of Pregnancy

    By the end of the third month of pregnancy, your baby is fully formed. Your baby has arms, hands, fingers, feet, and toes and can open and close its fists and mouth. Fingernails and toenails are beginning to develop and the external ears are formed. The beginnings of teeth are forming. Your baby's reproductive organs also develop, but the baby's gender is difficult to distinguish on ultrasound. The circulatory and urinary systems are working and the liver produces bile.

    At the end of the third month, your baby is about 7.6 -10 cm (3-4 inches) long and weighs about 28g (1 ounce).

    12 Weeks

    Since your baby's most critical development has taken place, your chance of miscarriage drops considerably after three months into the pregnancy.

    Pregnancy Week-By-Week Newsletter

    Delivered right to your inbox, get pictures and facts on
    what to expect each week of your pregnancy.

    Today on WebMD

    hand circling date on calendar
    Track your most fertile days.
    woman looking at ultrasound
    Week-by-week pregnancy guide.
     
    Pretty pregnant woman timing contaction pains
    The signs to watch out for.
    pregnant woman in hospital
    Are there ways to do it naturally?
     
    slideshow fetal development
    Slideshow
    pregnancy first trimester warning signs
    Article
     
    What Causes Bipolar
    Video
    Woman trying on dress in store
    Slideshow
     
    pregnant woman
    Article
    Woman looking at pregnancy test
    Quiz
     
    calendar and baby buggy
    Tool
    dark chocolate squares
    Slideshow