The dilemma of the pain in the newborn

 

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© Photo Inserm – Patrick Delapierre

Curiously we know a lot on pain of the mother during delivery but much less that of the new born. Several techniques and drugs can infirm the biblical saying –thou shall deliver in pain –and that is of course important. Yet, we should not forget that the partner of this incredibly complex event, namely the new born is submitted also to a strong tension. The studies of Pr. H Lagercrantz (karolinska Stockholm) have shown that birth is a major stressful event. In his classical paper “the stress of being born” he has shown that the levels of stress molecules such as Cortisol or adrenaline are higher in the newborn than the mother and much higher than anything we shall experience in life. These molecules are released in response to the brain stress during the process and have an important function namely to facilitate the release of liquid from the lung alveolar system and thus to aerobic breathing.

 

What about pain? Studies of the same group show that C-section delivered babies are more responsive to pain than vaginal delivered ones. Experimental investigations made by our group show that the labor-triggering hormone –oxytocin – reduces pain in pups during delivery by reducing chloride levels in neurons of pain pathways. Thus, the hormone in addition to triggering labor and exerting neuro-protective actions also acts as an analgesic factor. This being said, in various conditions- preterm delivery for instance- it is mandatory to intervene and use anesthetic agents that might have some deleterious actions on the new born. Indeed, it is important to stress that the developing brain is not a small adult one, all its currents and processes differ from that of the adult. Therefore, the actions of molecules and drugs might exert very different effects. Hence the importance of determining their actions specifically in pups and animal models. This is mandatory in order to solve the dilemma of using or not anesthetics and which ones in babies.

Y. Ben-Ari

bibliographical references:

Carabajal R et al Sedation and analgesia practices in neonatal int ensive care units (EUROPAIN): results from a prospective cohort study, The Lancet septembre 2015

Char N, editorial Lancet Negotiating the dilemma of anaesthesia and sedation in NICUs, The Lancet, septembre 2015

Ben-Ari Y Is birth a critical period in the pathogenesis of autism spectrum disorders? Nature Reviews Neuroscience 2015 Aug;16(8):498-505.

Tyzio R et al Maternal oxytocin triggers a transient inhibitory switch in GABA signaling in the fetal brain during delivery. Science 006 Dec 15;314(5806):1788-92.

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