On the Move
Around the ninth week of pregnancy, your baby starts making her first movements. Those movements are probably visible with an ultrasound, even though they can't be felt for several more weeks. By 13 weeks, your baby may be able to put a thumb in her mouth, although the sucking muscles aren't completely developed yet.
Although your baby's first muscle movements were involuntary, the first voluntary muscle movements occur around week 16. After this point, awake or asleep, your baby moves 50 times or more each hour, flexing and extending her body, moving her head, face, and limbs, and exploring her warm, wet home by touch. A baby may touch her face, touch one hand to the other hand, clasp her feet, touch her foot to her leg, or her hand to the umbilical cord. By week 37, your baby has developed enough coordination so that he or she can grasp with the fingers.
Along with these common movements, babies perform some odder activities, including licking the uterine wall and "walking" around the womb by pushing off with its feet.
Fetuses also react with motion to their mother's actions. For instance, ultrasounds have shown a fetus bouncing up and down when the mother laughs. Watching this on the screen, moms-to-be often laugh harder, and the fetus starts moving up and down even faster!
Second or third children may have more stretching room in the womb than first babies because a woman's uterus is bigger and the umbilical cord longer after her first pregnancy. These children usually get more motor experience in utero and tend to be more active infants.
By week 29, you should be feeling your baby move at least 10 times an hour.