During the development of pregnancy, the processes change periodically. inhibition and excitation in the central nervous system . After fertilization and implantation of the ovum, as a result of irritation of the interoceptors of the uterus and constant afferent impulses from them, a focus of persistent excitation (gestational dominant) appears in the cerebral cortex. Due to reciprocal relations, the activity of the crust itself is suppressed. Decreases its inhibitory effect on the subcortex, which is released.
Such a relationship between the cortex and subcortical structures exists during the first three months of pregnancy and is again gradually restored to its end, reaching a maximum in the last 12 days before delivery. Then the reflex activity of the spinal cord increases. This leads to an increase in the sensitivity of the uterus to various humoral and nervous stimuli coming from both the mother and the fetus. With the exception of two periods, the activity of subcortical centers has been suppressed throughout pregnancy.
The state of central regulation determines the pregnancy-specific changes in the peripheral nervous system, which are manifested by neuralgic pains, especially of the ishalgic nature, rare spasms of the leg muscles, the appearance of paresthesias and various disorders of vision and hearing.
At the very beginning of pregnancy, the tone of the vegetative nervous system also increases, which explains the appearance of vasotonic reactions of - drooling, nausea, vomiting, addiction to dizziness. Sometimes the processes of inhibition predominate, which leads to relaxation of the smooth muscles of the internal organs. This contributes to the development of pyelitis, intestinal atony with the subsequent occurrence of constipation.