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    Your baby’s got some nerve!

    A growing fetus in the thirteenth week

    Your baby’s development

    She’s all ears (and eyes, and muscles and nerves).
    This week, your baby's organs, nerves, and muscles have formed and are beginning to work together to help her grow. She’s probably about the length of a lemon, and her head is probably about half the size of her body.

    Eyes and ears are clearly defined, and eyelids are fused together to protect her still-developing eyes.

    Tissue which will harden into bone is developing in the head, arms, and legs. Tiny ribs might be visible via ultrasound.

    Her vocal chords are developing, and the circulatory system is helping to clear toxins from her body.

    She's already moving her body in jerky motions as she flexes her arms and kicks her legs, but you won't feel movement for at least several more weeks.
    Sliced red and green apples

    Your nutrition and health

    Eat this, not that.
    In your 2nd trimester, your baby is growing quickly. Remember to make healthy choices and get all the vitamins, minerals, nutrients, and calories you need to support your baby’s growth and development. However, in your 2nd trimester, you only need to add about 340 calories a day to your diet. For example, that would be 1 peanut butter and jelly sandwich or 1 cup lowfat milk, a piece of fruit, and cheese.

    Eat
    Fresh or frozen fruits and vegetables: They’re packed with vitamins and minerals. Plus, they’re low in fat and are often a good source of fiber.

    Protein-packed foods: Foods such as lean meats, dried beans, low-fat dairy and peanut butter are full of protein, which is essential to your baby’s growth.

    Fact: Different-colored fruits and vegetables have different levels of nutrients and vitamins. As a general rule, try to vary the types and colors of fruits and vegetables you eat every day.

    Avoid
    Soft cheeses: Avoid soft cheeses like feta, queso blanco, Brie, Camembert, blue-veined cheeses, and Panela are safe if clearly labeled "made with pasteurized milk".

    Shark, tilefish, king mackerel, and swordfish: These fish could contain high levels of mercury. Instead, eat fish that are lower in mercury, such as salmon.
    A woman weighing herself

    Things to think about now

    Your next doctor visit is here.
    Around week 13, you might have another prenatal doctor visit. From now until about week 28, most of your doctor appointments will follow a routine. Your doctor will monitor:

    • Your weight and blood pressure
    • Your urine (to check for proteins and sugars)
    • Your baby's growth (by measuring the size of your uterus)
    • Signs of swelling in your face, ankles, hands, or feet
    • You might be hearing your baby's heartbeat for the first time during this visit. This is often possible after the 12th week of pregnancy.
    • If you haven't decided about prenatal testing, now is a good time to discuss the options with your doctor.
    • CVS (chorionic villus sampling) is one test that detects chromosome and other genetic abnormalities, usually between the 9th and 14th weeks. Learn more about prenatal screening and diagnostic testing.

    Remember to bring your list of questions or concerns to each visit. If you have immediate concerns, discuss them with your doctor right away.
    A woman about to eat a green apple while outside

    What happens next week

    The reproductive system starts to take shape.
    While the reproductive organs begin to develop, your baby's thyroid gland is already working and making hormones.