When you visit your doctor for confirmation of pregnancy, she will determine your due date by adding 40 weeks to the beginning of your last period. Those 40 weeks are known as the gestation period, a time of rapid fetal growth and development. Fetal movement is one of the most exciting events during this process.
Before your baby can start moving within the womb, he'll need to develop a brain, spinal cord, heart and other essential organs. According to the Mayo Clinic, these body systems begin to develop in the third week of gestation and continue to differentiate throughout your first trimester of pregnancy. His bones will develop into a skeleton around week 15.
According to the Mayo Clinic, fetal movement may begin as early as 8 weeks, when your fetus is about 1/2-inch long. By week 16, those movements are becoming more coordinated and can be seen during an ultrasound exam.
The American Pregnancy Association says that some women can feel their babies move within the womb at 13 to 16 weeks of gestation, while the normal range for noticing the first fetal movement is 13 to 25 weeks. This phenomenon, known as quickening, is a subtle flutter that can feel like gas. Second-time mothers generally notice quickening sooner than women who are pregnant for the first time.
Your baby will move within your uterus to stretch his arms and legs, to reach a more comfortable position and in response to noise or changes in your emotional state. As your pregnancy advances, you may notice she has a definite cycle of sleeping and waking. After 32 weeks, your baby may fit so tightly within the uterus that he moves less often.
From 28 weeks on, your doctor may ask you to count fetal movements for a period of time each day to monitor your baby's well-being. The American Pregnancy Association recommends checking to see if your baby moves at least 10 times during a two-hour period. If not, try another two-hour period. If you still don't measure 10 movements, contact your doctor.