Most websites about child development simply note that at some point around 20 weeks, you will feel your baby move. Women who have already been pregnant will often feel the baby move a few weeks earlier (most likely because they know what to expect). The location of the placenta in the uterus can also affect how likely it is a woman can feel a fetus move. When the placenta is on the front of the womb, it takes a bit longer for a woman to feel a fetus move. But fetal movement is actually way more exciting than just whether you notice it or not. It actually provides some cool insight into two aspects of child development: (1) how motor development changes across development and (2) how active your child is going to be after birth.
We all know that the fetus is moving in utero, but most are surprised to learn that movement begins about 5-6 weeks after conception! Surely, the baby isn’t exactly a back-up dancer to Beyonce at 5-6 weeks, but he or she begins to bend at the neck and spine and that movement grows increasingly complicated over the first trimester.  Over the next few weeks, the fetus will begin to wave arms and legs, wiggle fingers, touch the outside of the amniotic sac, play with the umbilical cord, turn a head and move eyes, and will even begin to yawn. In the beginning, these movements are wild and not well controlled, but by about 12 weeks of age, the fetus is exhibiting all of the movement patterns that he or she will have at birth. Keep in mind, most women don’t feel their baby move or kick until around 20 weeks. So well before a woman is able to feel a fetus moving, there is a wild and crazy little back-up-dancer in training in there. By the time a fetus is full term, he or she responds to maternal movements (like walking, rocking, etc.), which suggests that the vestibular system – the sensory system found in the inner ear that helps us with balance and movement coordination – is functioning before birth. 
What’s interesting about fetal movement is that some babies are super active, while others are much more mellow. Turns out, this is pretty consistent over time – the most active fetuses in utero become the most active infants, toddlers, and children.  Stated differently, moms can often have a good guess at whether they are going to have a more physically active baby or not just by paying attention in pregnancy. Of course, it’s a bit relative. I thought #1 was going to be pretty physically active given how much I could feel movement, but when pregnant with my next child I realized baby #2 was really the active one. This is an observation that has turned out to be true well into childhood for both of them. It is also true that #1 is more active than many other children, just less active than my own #2.
Beyond general activity, fetus’ practice a few specific motor behaviors in the womb: hiccups (as young as 7 weeks after conception), swallowing (around 7 weeks after conception), and breathing (around 10 weeks after conception). These behaviors all prepare a baby to digest food, swallow milk, and breath after birth. Notably though, these behaviors aren’t particularly well coordinated in utero. For instance, breathing practice is not consistent in utero. Often, babies practice breathing (with amniotic fluid, not air) off and on throughout the day, but generally increases in frequently and regularity as the fetus gets closer to birth. 
Truly, the most important part is to pay attention to the movement pattern that is “normal” for your baby. If a parent has an idea of what a typical movement pattern is for his or her fetus, a parent will be better able to check in with a doctor if there is a concerning change in typical levels of behavior. Indeed, a mom I know showed up to the emergency room one night insisting that her baby always kicked like crazy during the Sopranos but tonight, baby was quiet. Sure enough, baby was in distress and needed some help. This doesn’t mean you should rush to the doctor immediately with every change in movement in utero, but paying attention to fetal movement (called kick counts later in pregnancy) can be an important diagnostic tool for the health of a baby. And even before they are born, it’s really about what is normal for your particular child.
 De Vries, J. I., Visser, G. H., & Prechtl, H. F. (1982).
 Lecanuet, J. P., & Jacquet, A. Y. (2002).
 DiPietro, J. A., Costigan, K. A., Shupe, A. K., Pressman, E. K., & Johnson, T. R. (1998).
 Govindan, R. B., Wilson, J. D., Murphy, P., Russel, W. A., & Lowery, C. L. (2007).