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Signs of Labor. regular, persistent contractions (vs. Braxton Hicks contractions) due to oxytocin release from pituitary loss of mucus plug (cervical dilation) rupture of amniotic membranes procession through stages 1, 2 and 3. Labor. What induces labor? Possible role of fetal adrenal gland
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Signs of Labor • regular, persistent contractions (vs. Braxton Hicks contractions) due to oxytocin release from pituitary • loss of mucus plug (cervical dilation) • rupture of amniotic membranes • procession through stages 1, 2 and 3
Labor • What induces labor? • Possible role of fetal adrenal gland • Stress > cortisol release from fetal adrenal > placenta releases prostaglandins > uterine contractions • Contractions > oxytocin release from pituitary
Stage 1 • longest (8 to 12 hours for first delivery) • involves effacement and dilation of cervix • caused by hormonal changes and force of myometrial contractions • as muscles of uterus shorten, pressure is applied to baby
Stage 1 • 10 cm = full dilation • effacement ranges from 0 - 100% (thinned to the point of disappearing) • “transitional phase” is often difficult
Stage 2 • fetal membranes often break at this point • mother feels urge to bear down • lasts from 1 to 2 hours; often painful • mother pushes, adding force of abdominal muscles to that caused by uterine muscles
Stage 2 • baby moves toward vaginal opening • “crowning” occurs when head is visible • episiotomy may be performed (80%) • after head is born, only a few pushes are required for rest of body to exit
Stage 3 • once baby is delivered, uterine cavity shrinks • placenta detaches • uterine contractions force placenta out within 15 minutes • uterine massage can facilitate placenta delivery
Medicalization of birthing:Episiotomies • estimated that rate should not be above 30% • many performed without a woman’s consent • fetal monitoring
Medicalization of birthing: cesarean sections • rate from 1975-2000: 20% • prior to 1970s, rate was 5% • defensive medicine?
C-sections • necessary when baby is in breech position or fetal distress is indicated • risks > fetal injury, maternal blood loss, infection, blood clots from bed rest
Medicalization, cont’d.: induction of labor • occurs in 10-15% of all hospital deliveries • involves prostaglandins applied to cervix and/or infusion of pitocin • often causes more intense, painful contractions
Induction • increased risk for use of pain medication, episiotomy, operative vaginal delivery, c-section • fetal risks > suffocation, physical injury
Midwifery • alternative care givers who offer a less invasive pregnancy experience • certified nurse midwives > attend graduate programs; usually practice in conjunction with univ. or med. school • licensed nurse-midwives • not nurses; practice in private homes or hospital birthing centers • trained through formal schooling and apprenticeships • must pass state board exams (avail. in 17 states)
Midwifery, cont’d. • lay midwives: • trained through schooling and apprenticeships • practice in states without licensing opportunities • can’t charge fees in some states • deliveries with midwives: • less medication, fewer interventions required • no diff. in duration of labor, perineal lesions, maternal blood loss • no diff. in birthweight, gestational age • vaginal birth rates higher
Lactation • pregnancy hormones caused growth of breasts • prior to birth, glands produce colostrum • after birth, prolactin stimulates milk production • when infant suckles, letdown reflex occurs:
Let-down reflex • sensory receptors in nipples stimulated • nerve impulse travels to brain • causes pituitary to release hormones oxytocin & prolactin • oxytocin causes myoepithelial cells surrounding alveoli to contract
Let-down reflex • prolactin causes milk synthesis • can be interfered with by stressors (blood vessel constriction) • can become conditioned reflex • prolactin causes shutdown of reproductive system
Benefits of breastfeeding for infant • Colostrum: • produced 2-5 days postpartum • high in protein; low in fat, carbs • contains intact cells (macrophages, lymphocytes) • antibodies (nonspecific IgAs) • Mature milk: • water, protein, fat, lactose • vitamins, minerals, salts, hormones
Breastmilk vs. formula • Cow’s milk-based formula has 3X greater protein levels • primary proteins: • in formula > casein (causes curdling) • in breastmilk > whey (easily digested) • amino acid taurine nearly absent in cow’s milk (now supplemented)
Breastmilk vs. formula • same levels of fat (50%) but types differ: • breastmilk has more cholesterol (protective?) • lipase present in breastmilk • sucrose added to formula to match high levels of sugar (lactose) in breast milk • bifidus factor present in higher levels in breast milk (promotes growth of “good” bacteria)
Breastmilk vs. formula • lactose promotes calcium absorption • both may contain environmental contaminants • viruses (HepB, HIV) can be transmitted thru breastmilk