Your baby's head is now about 1/3 of its total body length. The facial features are being defined. The body is growing quickly and the fingernails are developing. The baby's sex can usually be identified by this time period. Since the muscles are now functioning, the baby is active.
Your baby is in a period of rapid growth. By approximately 13 weeks of pregnancy, internal organs and systems (including the umbilical cord and placenta) are formed and functioning, the head is about 1/3 of its total length, and facial features are defined. The skin begins to be covered by lanugo, a fine, downy hair, and baby's sex can usually be identified. Typically, a fetus at 16 weeks will weigh about 7 ounces and be 5 ½ inches long.
At about 13 weeks your enlarging uterus can be felt just above your pubic bone. Your pregnancy has begun to "show". At about 14-16 weeks our doctors and nurses can begin to hear the baby's heartbeat. At 16-20 weeks you will begin to feel the baby move (quickening). You may begin to experience low back pain due to posture and hormonal changes.
Even though others may not yet see the signs, your body is clearly telling you that you're pregnant! By the beginning of the second trimester, however, "morning sickness" disappears for many women. If you're among the few who still find it a problem, remember that:
At about the 13th week, your uterus has grown large enough so it can be felt just above your pubic bone. This enlargement will continue gradually throughout your pregnancy, and may be more obvious if you've been pregnant before.
Some wonderful experiences are part of this time. One of the most exciting is hearing your baby's heartbeat for the first time. As early as 14 to 16 weeks, you may be able to hear the heartbeat during a visit to office with an amplifying device called a Doppler.
With such changes come some more symptoms. You may, for example, begin to experience some low back pain due to posture and hormonal changes. If you do, discuss this with your doctor.
Reprinted by Pregnancy.org, LLC from Her HealthCare.