Parturition & Lactation

1. Parturition and Lactation
Dr. Sara Sadiq
(MBBS, M.Phil)

2. Parturition
• Means birth of the baby
• Toward the end of pregnancy, uterus becomes progressively more
excitable.

3. Onset of labor  Hormonal Factors
• Progesterone: Inhibits uterine contractility
• Estrogen: stimulates uterine contractility.
• Oxytocin: increases uterine contractions
• Fetal hormones: oxytocin, cortisone, prostaglandin
• Prostaglandins: dilation and softening of the cervix
increase uterine contractions

5. Onset of labor  Mechanical Factors
• Stretch of the Uterine Musculature
• Stretch or Irritation of the Cervix
• Strong uterine contraction and pain from the birth canal cause neurogenic
reflexes from spinal cord that induce intense abdominal muscle contractions

7. Braxton Hicks Contractions
• Weak and slow rhythmical contractions during pregnancy
• Become progressively stronger toward the end of pregnancy

8. Positive feedback
Stretch of the cervix by fetal
head increases contractility

10. The Stages of Labor

11. Lactation
• Producing and Releasing Milk

13. Hormonal Effects On Lactation
• Estrogen: growth of ductile system
• Progesterone: development of lobule-alveolar system
• Both Estrogen and Progesterone inhibit milk production
• Prolactin stimulate milk production
• Oxytocin  "Milk let-down" reflex
• Maternal & fetal ACTH: stimulates lactogenesis

16. Oxytocin and Prolactin Regulation
• Oxytocin levels increase due to suckling of the breast by the infant
• In addition, sight, sound, or thought of the infant can also increase
oxytocin levels, causing milk ejection
• Prolactin release is also increased by suckling of the breast by the
infant (but not by audiovisual stimuli)
• Prolactin secretion
• inhibit secretion of GnRH by the hypothalamus
• Decreasing LH/FSH
• SUPPRESSION of the female ovarian cycles in nursing mothers

17. Breastfeeding  Infant Health Benefits
• COLOSTRUM
• Small amount for the immature digestive system
• ‘paints’ the digestive tract
• Low fat for easy digestion
• Contains mothers antibodies which boost infants’ immune system
• Acts as a laxative to ease passage of meconium

18. Breastfeeding  Infant Health Benefits
• Provides immunologic protection while the infant’s immune system
is maturing
• Antimicrobial agents
• Anti-inflammatory agents
• Immunomodulating agents
• Decreased infection rates
• Increased IQ rates  Contains long chain polyunsaturated fatty
acids that help the infant’s brain development

19. Breastfeeding  Mother Health Benefits
• Less postpartum bleeding
• More rapid uterine involution
• Weight loss
• Decreased premenopausal breast cancer rates
• Decreased ovarian cancer rates
• Lactational amenorrhea