Fetal movement begins in the second trimester. Some expectant mothers can feel their baby moving by the fourth month, according to What to Expect. Most women experience the sensation of fetal movement by the fifth month of pregnancy.
What to Expect states that early fetal movements consist of kicking, thumb-sucking and thrashing. While the fetus remains small, it is capable of performing somersaults in the uterus as well. Movements strengthen as the fetus grows.
These movements are sometimes confused with gas or muscle spasms, What to Expect notes. Most mothers who feel fetal movements early on in pregnancy have either experienced a prior pregnancy or are very thin and able to notice the sensations more easily.