From the beginning to the end of your pregnancy, your baby will develop rapidly, changing from a microscopic zygote into a full-term baby in approximately 40 weeks. You may be eager to begin feeling the kicks and flutters that indicate that your baby is moving. Most women begin feeling movement by the 20th week of pregnancy, or a bit sooner if this is not your first pregnancy.
First Trimester
During the first trimester, which is the first 13 weeks of pregnancy, your baby makes rapid developments. About one week after conception, the embryo implants in the uterus and begins to emit enough of the pregnancy hormone, human chorionic gonadotropin, or HCG, to cause a positive pregnancy test. Over the course of the next several weeks, your baby will develop a brain, spinal cord, digestive system, cardiovascular system, arms, legs, ears and face. During the eighth week, your baby will be able to contract his muscles and will begin moving, but you cannot feel these tiny movements yet. By the end of the first trimester, your baby is about 3 inches long.
Second Trimester
You may begin to feel your baby moving at approximately 18 to 20 weeks gestation. At first, these movements feel like little flutters, but as your baby grows, you may feel stronger kicks and punches. Once you start feeling movements, let your doctor know. During the second trimester, your baby develops fingernails and hair, and you may be able to find out the baby's sex via ultrasound. She may begin sucking her thumb, and she can make swallowing motions. She might begin to have a regular cycle of sleeping and waking up.
Third Trimester
As conditions inside your uterus become more crowded during the third trimester, your baby's movements may change into more squirming and less kicking. Your baby gains fat and weight, and by the end of the third trimester, he may weigh between 6 and 10 lbs. His skin becomes less red and wrinkled and he starts to look more like a newborn. His eyes open at the beginning of the third trimester, and the fine hair that covered his body, called lanugo, begins to disappear. Most babies turn to the head-down position in preparation for delivery, but some babies remain in the breech position.
Kick Count
Your doctor may ask you to monitor your baby's movements and to report a decrease in kicks and squirms. This is important, because a marked decrease in movements may mean that there is a problem with the baby. If you do not feel your baby move for several hours, your doctor may want to see you to run some tests to check your baby's health. These tests might include an ultrasound or an electronic fetal non-stress tests. If you are concerned about your baby's movements, contact your health care provider right away.
