Though the fetus is largely a passive player in work, the effects of pressure and circulatory changes that happen with contractions cause discoverable physiologic differences during pregnancy. Such differences can be broken down into the following:
Neurologic System
Uterine contractions put some leverage on the fetal head, so the same reply concerned with that of any example of increased intracranial pressure happens. The fetal heart beat rate ( FHR ) decreases by as much as five bpm in a contraction as fast as contraction strength reaches forty mm Hg. This decrease appears on fetal heart monitor as an early deceleration pattern.
Cardiovascular System
The power to reply to cardio changes is generally mature enough the average of fetus is untouched by the continuous adaptations of heartbeat rate that happen with labor-a slight slowing and then a revert to normal levels. In a contraction, the arteries of the uterus are quickly constricted and , the filling of cotylodons just about completely halts. The quantity of nutrient elements, including oxygen, exchanged in this time is reduced, causing a slight but unimportant fetal hypoxia.
Increased intracranial pressure from uterine force on the fetal head serves to keep circulation from falling below normal during the period of a contraction.
Integumentary System
The pressure concerned in the birth process is frequently mirrored in minimum petechia or ecchymotic areas on the fetus.
Musculoskeletal System
The force of uterine contractions has a tendency to push the fetus into a position of full flexion.An entirely flexed position is the most beneficial for birth as it can speed work.
Breathing System / Pulmonary
The process of work seems to help in the maturation of surfactant production by alveloli in the fetal lung. The pressure applied to the chest from contractions and passage thru the birth canal clears it of lung liquid. So , the child born vaginally has a tendency to be able to build respirations simpler than the fetus born by cesarean birth.

