Hormonal physiology of childbearing: evidence and implications for women, babies, and maternity care.
Promoting healthy physiologic birth NACPM webinar Jan 2015
Hormonal physiology of childbirth: complexity.
we still don´t know why labor starts. What leads up to the normal physiological labor?
Hormonal physiology of childbearing has evolve over time to optimize survival for mothers and babies and for the species.
Optimize survival during birth, but also after birth by attachment and breastfeeding.
Overview of physiology of four key hormonal systems.
Oxytocin: reduces fear and stress (amygdala), increases relaxation and receptivity, analgesic, involved in central motivation and reward systems, during childbearing, oxytocin is involved with labor, birth attachment and lactation. (section 3.1). Stimulates dopamin paths. Rythmic contractions.
Beta-Endorphins (BEs): central (brain-based) analgesic effects, reduce stress and promote phychological well-being, involved in central motication and reward systems (dopamin) and in childbearing, BEs promote analgesia, breastfeeding and attachement. (section 4.1.)
Epinephrine, norepinephrine (E-NE) and related stress hormones: E-NE mediaate flight or flight stress responses, shift blood away from mon-essential organs. In childbearing, excess E-nne may decrease uterine blood supply, labor contractions, late-labor E-NE surges support effective pushing (FER), newborn protection, transition (CA categolamine surge), Cortisol matures fetal organs, prepares for labor and birth (section 5.1.).
Prolactin (PRL): Major hormone of breastmilk synthesis, promotes physiologic adaptation to maternity, in childbearing, supports fertility, labor and birth, lactation, maternal attachement, homone of paternity (sec 6.1.)
Beneficial hormonal physiology pathway (healthy birth pathway). (read the research summary 10 pages!)
Hormonal processes of physiologic childbearing anticipate and prepare for upcoming processes and biological needs.
Poster: pathway to a healthy birth.
sec. 2.1.
Late pregnancy hormones – Active labor hormones – 1st hours – postpartum…
Late pregnancy:
Preparation for efficient labor: Uterine OT and prostaglandin (PG) reseptors rise, preparing for effective hormonal actions in labor and birth. The shorter the labor, the safer it is in the wild. These prepare the body for labor and birth.
Number of receptors change in time. More or less locks that can be opened. The more oxytocin receptors mother has, the more the uterus muscle can react to it.
Preparation for stress reduction and pain relief in labor: Maternal central BEs receptors rise and maternal central OT receptors rise.
Fetal preparation for labor safety and newborn transition: Fetal E-NE (catecholamine, CA) receptors rise, preparing for an effective late labor catecholamine surge, optimizing fetal safety and preparing for newborn transition. Important for the late stage of birth.
Preparation for lactation and attachment. Mammary and central OT and PRL receptors rise, preparing for hormone actions that optimize lactation and maternal-newborn attachemnent. Maternal central BEs receptors rise, preparing for hormonal actions that optimize labor analgesia and postpartum maternal-newborn attachment. Reward center active.
Active labor
hormonal processes promote progress in labor.
Several OT positive feedback cycles accelerate OT release. Central OT release accelerates OT release. Stronger labor leads to increase in sensations leads to increase in central OT release leads to increase in OT to uterus leads to stronger labor. Positive feedback cycle.
Epidural takes away the sensation breaking the loop and affects oxytocin release.
Birth and early pp hours.
Peak OT levels: skin-to-skin activates between mother and baby in first pp hour produce highest levels of PT (up to 10x elevated). these OT elevations promote uterine contractions, prevent bleasding. Central OT elevations (maximally) benefit breastfeeding, attachment.
Normal newborn transition: immediate skintoskin contact