Fetal movement refers to the activity of the fetus inside the mother’s womb which is caused due to the muscle activities of the fetus. The initial movements of the fetus are felt during the embryological stage.
These first movements are not reflexive in nature. They are self generated due to the nerve impulse in the spinal cord. The fetal movements due to the muscle activity begin with the maturity of the nervous system of the fetus and as a result, the muscles react to the stimulus.
When the fetus becomes six months old, it is able to move its neck and curve its back. An ultrasound is generally carried in the end of first trimester to observe the motion in the arms and sometimes, legs of the embryo. By the 12th week in the second trimester, the movements become more prominent and the embryo can be felt when it kicks inside the mother’s womb.
During this period, the baby can curl its toes and hold its feet and sometimes it can even scratch with its fingernails. By this time the baby has developed to the extent that it can respond to external stimuli and therefore reacts if touched.
During the 12th week, development of other parts also takes place including the thoracic diaphragm which moves up and down. However when the baby turns 16 weeks old, this movement is generally lost and can be felt again during the last trimester.
The observation of the initial movements during the second trimester is referred to as “quickening”. Quickening occurs during the fifth month when the baby is able to kick inside the womb. The motions of the limbs of the fetus reach a complicated level by this period.
The fetus is able to flex its ribs and joints. The fetus can move those joints which have developed completely. Generally it has been observed that women who have already had a child are much more perceptive of quickening.
Some women can feel quickening in the 14th week of pregnancy because their uterine muscles become relaxed due to the birth of previous child. By 21st week, the movements of the fetus become almost regular and are much easier to observe.