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4.0 Birthing and Physiology

The benchmark outcome of pregnancy is the normal vaginal birth of the baby, without any medical or pharmacological intervention and without complication for either mother or baby, followed by the baby being able to latch and breastfeed well.
This may not be achievable for some women for whom the availability of skilled medical, nursing and pharmacological assistance is essential, but it is possible for the majority of women in the World.

Normal labor is a fragile entity. Once intervention occurs then a cascade of interventions inevitably follow.1

Kroeger, 2004

Health care professionals have a responsibility to support and facilitate normal birthing. What happens to the mother during birthing has far-reaching effects on her relationship with her baby, her ability to breastfeed and the health of the mother and her child.

Poster available for purchase from NHS, UK

Poster available for purchase from NHS, UK

Lactation physiology

Lactogenesis is the making of breastmilk. There are three distinct phases. 2

  1. Secretory differentiation commences during pregnancy.
    • also known as lactotgenesis I (LI)
    • pregnancy hormones promote cell differentiation and growth of milk ducts and stimulate mammary cells to prepare to synthesise milk
    • most women will see some evidence of a milky secretion (colostrum) from their breasts during their pregnancy

  2. Secretory activation. The initiation of lactation begins biochemically around 30 - 40 hours after birth.
    • also known as lactogenesis II (LII)
    • changes occur as a result of endocrine function, entirely dependent on the right mix of hormones:
      • progesterone levels drop as a result of the removal of the placenta, AND
      • prolactin levels are high as they are at the time of birthing, in the presence of
      • normal insulin, thyroid hormones and glucocorticoids
    • the mother experiences the sensation of the milk 'coming in' around 70 hours after birth

  3. Lactogenesis III (LIII) is the maintenance of ongoing lactation.
    This autocrine function is dependent on frequent, effective removal of milk from the breasts.

Workbook Activity 4.1

Complete Activity 4.1 in your workbook.

What could delay or inhibit secretory activation?

Hint: Remember it's an endocrine function, therefore consider hormonal causes.

  • Accidents at birthing may cause endocrine disruption of lactogenesis. For example:
    • retention of a functional portion of the placenta that continues to secrete progesterone, 3
    • a haemorrhage severe enough to cause Sheehan's syndrome (pituitary gland necrosis). 4
  • A delay is common in women with insulin-dependent diabetes mellitus 5
  • Up to 80% of mothers of very premature infants have difficulty establishing lactation. 5
  • There is an increased incidence after assisted deliveries. 6
    Finding the cause of this delay and relating it to the physiology of lactogenesis has led researchers to look at the effect of stress.

Stress and breastfeeding

High stress levels are correlated with high cortisol levels. Cortisol in normal concentrations, is necessary to initiate secretory activation successfully.

  • Markers of both fetal and maternal stress during labor and delivery are associated with delayed breast fullness.7
  • Maternal stress seems to interfere with the release of oxytocin causing poor milk removal, and a newborn who experienced stress during labor and delivery may be too weak or too sleepy to latch on and suckle effectively.8
  • Onset of lactation occurred later in women who had higher cortisol levels. Primiparous women had higher levels than multiparous women. Stress during labor and/or delivery is likely to be a significant risk factor for delayed onset of lactation.9

What should I remember?

  • that interventions in labor have far-reaching effects on mother and infant
  • the 3 stages of lactation
    • when each commences
    • what controls their initiation or, in the case of LIII, what maintains it
    • the timing of their occurrence
  • the factors that can interfere with secretory activation

Self-test quiz

Match an item from the column on the left with an item from the column on the right. Click on an item in one column, then on its matching response from the other column

Notes

  1. # Kroeger M et al. (2004) Impact of Birthing Practices on Breastfeeding: Protecting the Mother and Baby Continuum
  2. # Czank C et al. (2007) Hormonal control of the lactation cycle
  3. # Anderson AM (2001) Disruption of lactogenesis by retained placental fragments
  4. # Kilicli F et al. (2013) Sheehan\'s syndrome.
  5. # Hartmann P et al. (2001) Lactogenesis and the effects of insulin-dependent diabetes mellitus and prematurity
  6. # Dewey KG et al. (2003) Risk factors for suboptimal infant breastfeeding behavior, delayed onset of lactation, and excess neonatal weight loss
  7. # Chen DC et al. (1998) Stress during labor and delivery and early lactation performance
  8. # Dewey KG (2001) Maternal and fetal stress are associated with impaired lactogenesis in humans
  9. # Grajeda R et al. (2002) Stress during labor and delivery is associated with delayed onset of lactation among urban Guatemalan women