The autonomic nervous system seems to work well, whatever the mode of delivery

In late pregnancy, the human body carefully prepares the fetuses to the rigors of life outside of uterine protection. Levels of cortisol, a stress hormone, skyrocket and rocket during work. Catecholamines, another stress hormone, also increase at birth, boosting baby's functions to regulate breathing, heartbeat, blood pressure, and energy metabolism at birth. Oxytocin increases, promoting contractions for the mother during labor and stimulating milk production after the infant's birth.

These processes may also play a role in preparing the fetal brain during the transition to life outside the uterus by preparing the autonomic nervous system and adapting its brain connections. The autonomic nervous system acts as the autopilot of the body, recording the information it needs to ensure the smooth functioning of the internal organs without voluntary action, for example by ensuring that the heart beats and the eyelids blink at regular intervals. His yin, the sympathetic division, stimulates the bodily processes while his yang, the parasympathetic division, inhibits them.

Pre-term infants have reduced autonomic function compared to their term peers and also face severe impairment of neurodevelopment later in life. But is there a difference in the function of the autonomic nervous system in full-term babies after delivery compared to infants delivered by caesarean section (Caesarean section)?

A team of the Inova National Children's Research Collaborative Program (CNICA) – a research collaboration between Children's Nationals in Washington, DC and the Inova Hospital for Women and Children in Virginia – has decided to answer this question in an article published online on July 30, 2019, in Scientific reports.

They recruited newborns who had a normal full term pregnancy and recorded their brain function and cardiac performance by the age of 2 days. Infants whose condition was fragile enough to require observation in the neonatal intensive care unit were excluded from the study. Of the 167 infants recruited for the prospective cohort study, 118 newborns had sufficiently reliable data to include them in the research. Among these newborns:

• 62 (52.5%) were born by badl birth
• 22 (18.6%) started with badl delivery but eventually went on to caesarean section due to a delay in progression, a failure of labor induction or intolerance to the fetus
• And 34 (28.8%) were born by elective cesarean section.

The CNICA research team bundled babies for comfort and slipped electrode nets onto their tiny heads to simultaneously measure heart rate variability and electrocortical function using techniques. non-invasive. The team hypothesized that work-exposed babies would have increased autonomic tone and higher cortical electroencephalogram (EEG) power than babies born by caesarean section.

"In a low-risk group of full-term babies, the autonomic nervous system and the cortical system seem to work well whether or not the babies are exposed to work before birth," says Sarah B. Mulkey, MD, Ph.D. ., Neonatal fetal neurologist from the Division of Fetal Medicine and Transition of the Children's National and lead author of the study.

However, infants born by caesarean section after a period of labor had a significant increase in heart rate. And infants born by caesarean section during labor had a significantly lower EEG gamma frequency at 25.2 hours compared to the other two groups studied.

"Together, these findings suggest a possible increase in stress response and awakening difference in infants who started with badl delivery and completed delivery with caesarean section," said Dr. Mulkey. "There is so little published research on the neurological effects of the delivery method, so our work is helping to provide a normal point of reference for future studies of high-risk infants, including pre-term infants. . "

As the research team found little difference in autonomic tone or in other EEG frequencies when infants were aged one day, future researches will explore these measurements at different times from the beginning of the life of the newborn, as well as the role of the sleep-wake cycle on the heart. rate of variability.