Chapter 13: Labor and Birth Processes

Chapter 13: Labor and Birth Processes

• Labor and birth are affected by five factors: passenger, passageway, powers, position of the mother, and psychologic response.
• The passenger includes the fetus and the placenta.
• Factors affecting the passenger include the size of the fetal head, fetal presentation (part of the fetus entering the pelvic inlet), fetal lie (spine-to-spine relationship), fetal attitude (relation of fetal body parts, normal is general flexion), and fetal position (presenting part, e.g., occiput, sacrum, chin).
  • 96% of births are cephalic (head first)
  • 3% are breech (buttocks or feet first)
  • Other percentages may be shoulder presentations
• Fontanels are soft spots on a baby's skull.
  • Posterior fontanels are triangular and close by 6-8 weeks.
  • Anterior fontanels are diamond-shaped and close by 18 months.
• The passageway refers to the birth canal.
  • It is made up of the bony pelvis (ilium, ischium, pubis, sacral bones), cervix, pelvic floor muscles, and vagina.
  • Four basic pelvis types: gynecoid, anthropoid, android, and platypelloid.
• Powers refer to the contractions of the uterus.
  • Primary powers are involuntary uterine contractions that cause effacement (thinning and shortening of the cervix) and dilation (widening of the cervix).
  • Secondary powers are bearing-down efforts by the mother.
• The position of the mother during labor can impact the process, affecting the mother's comfort and other adaptations to labor. Positions should promote woman's comfort and adaptability during labor.
• Psychologic response includes the mother's psychological state and how it affects the labor process.
• There are seven cardinal movements that occur in vertex presentations. Those are engagement, descent, flexion, internal rotation, extension, external rotation, and expulsion.
• Fetal adaptations to labor include changes in fetal heart rate (average 140 beats per minute, 110-160 range), circulation, and respiration (to prepare for breathing).
• Maternal adaptations to labor include changes in cardiovascular activity (output peaks temporarily during contractions), respiration, kidneys, the integumentary system (stretching of the vagina), musculoskeletal system (fatigue), neurologic system (euphoria, amnesia), gastrointestinal system (decreased motility, nausea, belching), and endocrine changes (decrease in progesterone, and increase in estrogen, prostaglandins, oxytocin and metabolism).
• Labor process includes the process of moving the fetus, placenta, and membranes from the uterus and through the birth canal.
• Various changes in the woman's reproductive system occur in the days and weeks before labor begins.
• Stages of labor:
  • First stage: begins with regular uterine contractions and ends with full cervical dilation.
  • Second stage: begins with full cervical dilation and ends with the delivery of the baby.
  • Third stage: begins with birth of the baby and ends with the expulsion of the placenta.
  • Fourth stage: the postpartum period, usually lasting about two hours after delivery of the placenta. The mother and baby are recovering.
• Signs preceding labor: lightening or dropping (2 weeks before term); bloody show (mucus plug).
• Onset of labor: changes in the maternal uterus, cervix, and pituitary gland.