What Does a 13-Week-Old Fetus Look Like?

During the 13th week of pregnancy, a baby gains weight and grows rapidly, and some of the body's systems are already functioning. As the first trimester ends, so do a few worries for the mother as she becomes more comfortable with the physical changes taking place in her body. It is important to still watch for any physical signs of complications.

  1. Week 13 of Pregnancy

    • The 13-week mark is a monumental time for many moms. Thirteen weeks marks the end of the first trimester, during which time spontaneous miscarriage more frequently occurs. At this point, the mother's body has adjusted to the increasing levels of hormones in her blood and she should begin to feel much better. Morning sickness may also begin to diminish.

    Size of 13 Week Fetus

    • The baby weighs about 14 to 20 g, which is approximately 1 1/4 oz. The length from the crown of the head to the buttocks is about 2.6 to 3.1 inches. The baby's head, which has been significantly larger than its body for the first 12 weeks, is now about one-third the size of the baby's total body.

    Fetus Features at End of First Trimester

    • The baby's body is covered with a soft, fine hair called lanugo. The toes and fingers are well formed and separate. Sockets for all 20 teeth are now in the gums. The ears have now moved into the correct position on the side of the head, and the eyelids meet and will fuse together. The kidneys and urinary tract are functioning now, so the baby begins to process and urinate small portions of the amniotic fluid that has been swallowed.

    Using Ultrasound to Monitor Fetal Growth

    • Depending on the obstetrician or midwife, the mother may have had an ultrasound by this point. The size and weight of the baby are approximations and are used to give a general overview of growth. In the event that the obstetrician or midwife has a concern about fetal growth, he may schedule the mother for additional testing. Keep in mind that babies grow at different rates and all the risks and benefits for any testing, if needed, are explained.

    Complications During Week 13

    • Although the threat of spontaneous first-trimester miscarriage may be over, you will need to contact your health care provider if you experience vaginal bleeding (filling more than one pad an hour is considered heavy bleeding) or if your amniotic sac ruptures. Your health care provider may monitor you more closely if you have an incompetent cervix (a cervix that will not stay closed), or if you have a history of miscarriages, stillborns or genetic complications.

    2. Previous:

    Next:

    • How to Treat Postpartum Hair Loss
      Every one of us loses hair each day. We may not notice this normal process until we brush our hair and see a large amount of loose hair on the brush. Pregnancy hormones often slow down daily hair loss. Our bodies gradually return to normal postpartum
    • How to Calculate a Due Date With the Woods Method or Nichols Rule
      The Woods method, also known as the Nichols Rule, was developed by midwifery professor Carol Wood Nichols. She developed this method for calculating due dates that takes into account the womans cycle length as well as her previous childbearing activi
    • Why Are Some Babies Born Bigger Than Others?
      Some mothers can expect a bigger bundle of joy than expected when the big day arrives. In a singleton birth, the average newborn weighs between 5.5 and 9 pounds. Mothers expecting larger than average babies may have to undergo a cesarean section to r