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Parturition and Prematurity Modules 17


Parturition and Prematurity Modules 17 & 18 AnS 536 Spring 2012 Developmental Outcomes for Premature Infants Prevention Decrease occurrence of premature births Fetal ... – PowerPoint PPT presentation

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Title: Parturition and Prematurity Modules 17

Parturition and PrematurityModules 17 18
  • AnS 536
  • Spring 2012

Hormonal Mechanisms Controlling Parturition
  • Humans
  • Gestation length 280 days
  • Cattle
  • Gestation length 283 days
  • During Gestation
  • Prostaglandin levels remain high
  • Quiescent uterus
  • Maintains pregnancy
  • Humans
  • Human chorionic gonadotropin (hCG) responsible
    for maintaining corpus luteum (CL)
  • CL produces progesterone
  • Third Trimester
  • Uterus becomes more excitable
  • Hormone levels change

Hormonal Mechanisms Controlling Parturition
  • Prior to parturition
  • Dilation of cervix
  • Contractions of the uterus
  • Progesterone levels decrease
  • CL and placenta increase production of relaxin

Hormonal Mechanisms Controlling Parturition
  • Cattle
  • Nearing term
  • Pressure within the uterus causes stress on the
    fetus, stimulating the release of fetal cortisol
  • Estradiol increases
  • Stimulates vaginal and cervical mucous secretion
  • Prostaglandin increases
  • Contraction of the uterus
  • Oxytocin production
  • Caused by increased pressure on the cervix,
    further increases contractions
  • Relaxin production
  • Relaxes pelvic ligaments

Hormonal Mechanisms Controlling Parturition
  • Cattle cont
  • Muscle contractions continue to increase
  • Pressure causes membrane rupture
  • Fetus begins to move into the birth canal
  • Fetus becomes hypoxic
  • Increases fetal movement
  • Increased muscle contraction and expulsion of

Process of Parturition
  • Three separate stages
  • Cervical dilation
  • Delivery of the fetus
  • Expulsion of the placenta

Process of Parturition
  • Stage I - Cervical Dilation
  • Cervical opening expands to a maximum of 10 cm
  • Longest stage of labor
  • Lasting a few up to 24 hours
  • Cervix dilates with increased pressure from the
  • Normal presentation fetal head applies pressure
  • Fetal head is the largest circumference among the
  • Abnormal presentation pressure on cervix may
    not be as great to promote maximum cervical
    dilation needed for fetal passage

Process of Parturition
  • Stage II Delivery of the fetus
  • Occurs once cervical dilation is complete
  • Fetus is able to pass through cervix and vagina
  • Fetal passage triggers stretch receptors in the
    vagina activating a neural reflex
  • Triggering contraction of the abdominal wall in
    synchrony with uterine contractions
  • Increased force pushes fetus through birth canal
  • Additional voluntary force via abdominal muscle
  • Complete passage through the canal
  • Fetus is still attached via umbilical cord
  • Umbilical cord is severed after complete delivery

Process of Parturition
  • Stage III Expulsion of the Placenta
  • Occurs shortly after delivery
  • Varies among species
  • Second wave of uterine contractions occur
  • Separate the placenta from the uterus
  • Expelled through the vagina
  • Uterine contractions constrict blood vessels
    supplying site of placental attachement
  • Prevent bleeding
  • Shortest stage of delivery

  • Noted when difficult, prolonged, or abnormal
    parturition occurs
  • Contributing factors
  • Presentation of fetus greatly affects the degree
    of dystocia
  • Breech births, etc.
  • Large birth weight
  • Small maternal pelvic measurements
  • First parity mothers
  • First-calf beef heifers have 16.7 dystocia vs
    2.7 seen in cows

  • Contributing factors cont
  • Fetal abnormalities
  • Genetic mutations
  • Maternal failure to recognize onset of
  • Seen in recipient dams carrying cloned fetuses
  • Maternal health and/or body condition score
  • Affects the stress and health of fetus
  • Labor may be untimely, too early
  • Avoiding fetal mortality
  • Timely recognition of problems
  • Proper assistance in labor process

Managing Dystocia
  • Forceps assisted vaginal delivery (humans)
  • Vacuum assisted vaginal delivery (humans)
  • Cesarean section
  • Performed often in humans
  • Compromised delivery
  • Mothers can opt for c-sections
  • Livestock
  • Often used as a last resort
  • Incurred veterinary cost is high
  • Cause scaring in the uterus
  • Difficult for the animal to breed back
  • Drugs such as oxytocin, prostaglandin, and
    corticoids are administered

Managing Dystocia
  • Litter bearing animals
  • Managed through c-sections
  • First of several fetuses can be stuck in the
    birth canal
  • Can compromise the rest of the litter
  • Survivability declines with added time of stress
  • Canine and feline C-sections
  • Differ from large animal and humans
  • Small animals are put under general anesthesia
  • Better restraint of animal, fastest and safest
    way to deliver
  • Cattle and humans epidural anesthesia

Induction of Parturition
  • Protocols depend upon
  • Length of gestation
  • Size and development of fetus
  • Cattle
  • Long acting corticosteroids
  • Lead to parturition in 2-26 days
  • Wide time range can be disadvantageous
  • May have detrimental effect on dam influencing
    preexisting health condition
  • Fetal membrane retention is low

Induction of Parturition
  • Short acting corticosteroids
  • Frequently used, very effective
  • Injected within 2 weeks of due date
  • Parturition usually occurs in 24-72 hours
  • Colostral immunoglobulins are normal
  • Influence fetal lung development
  • Retained fetal membranes are high
  • Also related to age of calf younger calf high
    incidence of retained membranes

Induction of Parturition
  • Prostaglandins
  • Effective method
  • No advantage over corticosteroids
  • Estrogens
  • Old method
  • Poor efficacy

Induction of Parturition
  • Combinations
  • Goal reducing rate of retained placentas,
    avoiding induction failures and calf mortality
  • Short acting corticosteroids estrogen
  • Long acting corticosteroids short acting
    corticosteroids or prostaglandins
  • Short acting corticosteroids prostaglandin

Multiple Pregnancies
  • Greater demand on the mother and increased risk
    on fetus
  • Nutritional demand is higher
  • Iron and folate needs increase
  • Anemia is reported more frequently
  • Morbidity and mortality of twins is higher
    compared to singleton pregnancies
  • Increased risk of delivering prematurely

Multiple Pregnancies
  • Mode of delivery can be more difficult
  • Plays major role in infant outcome, especially
    second born twins
  • Cesarian-cesarian
  • Vaginal-vaginal
  • Vaginal-cesarian
  • Vaginal-cesarian mode is most detrimental to
    second born twin
  • Presentation and birth weight of twins greatly
    affects mode of delivery and outcome of infant

Multiple Pregnancies
  • Congenital defects
  • Neural tube defects
  • Cardiac abnormalities
  • Bowel atresia
  • Other problems
  • Conjoined twins
  • Twin reversed arterial perfusion sequence
  • Poor fetal growth
  • Placentation
  • Amniocity
  • Freemartin (cattle)

Multiple Pregnancies
  • Animals designed to carry singleton pregnancies
  • Women
  • Cows
  • Mares
  • Animals designed to carry multiple pregnancies
  • Sows
  • Ewes
  • Queens
  • Bitches
  • Rodents

Perinatal Death
  • Preterm birth is the leading cause of neonatal
  • Lack of development of body systems is underlying
  • Conditions that can occur with prematurity
  • Hyaline membrane disorder
  • Respiratory distress syndrome
  • Bacterial infections
  • Intraventricular hemorrhage
  • Periventricular leukomalacia
  • Cerebral palsy
  • Necrotizing enterocolitis
  • Cardiac problems
  • Kidney problems

Preterm Labor
  • Occurs prior to expected delivery date
  • Occurs for a variety of reasons
  • Prelabor rupture of membranes
  • Can lead to amnionitis
  • Methods to prevent labor
  • Stop /delay onset of pre-mature births
  • Do not guarantee a healthy infant
  • Planned interventions to terminate pregnancy
  • Serious maternal illness
  • Problems affecting fetal well being or growth

Preterm Labor
  • Preterm labor prevention
  • Social measures
  • Ad campaigns increasing awareness
  • Smoking
  • Sexually transmitted diseases
  • Physical measures
  • At home uterine-activity monitoring
  • Bed rest
  • Cervical assessment
  • Surgical measures
  • Cervical cerclage

Preterm Labor
  • Preterm labor prevention cont
  • Pharmacological agents
  • Betamimetic drugs
  • Stop uterine contractions in active labor
  • Most widely used among other labor-inhibiting
  • Inhibitors of prostaglandin synthesis
  • Strong and practical use in preventing labor
  • Antibiotics
  • Some use in preventing early labor in women with
    bacterial vaginosus

Preterm Labor
  • Types of preterm births
  • Antepartum death
  • Lethal malformations
  • Fetal outcome cannot be changed, vitality of
    mother is important
  • Multiple pregnancies
  • 50 of all multiple pregnancies result in
    premature delivery
  • Elective deliveries
  • Maternal and/or fetal pathology
  • Preclampsia
  • Antepartum hemorrhage
  • Intra-uterine growth restriction

Preterm Birth
  • Concerns
  • Increased morbidity and mortality
  • Intraventricular hemorrhage (IVH)
  • Periventricular leukomalacia (PVL)
  • Cerebral palsy
  • Necrotizing enterocolitis (NEC)
  • Retinopathy of prematurity (ROP)
  • Respiratory distress syndrome (RDS)

Preterm Birth
  • Physiological consequences
  • Infants body system are not prepared to function
    on their own
  • Numerous conditions that result from prematurity
    can be treated and maintained
  • Depending upon extent of prematurity, morbidity
    of the child may be great

Preterm Birth
  • Conditions can lead to
  • Permanent injuries
  • Mental retardation
  • Chronic lung disease
  • Loss of vision and hearing
  • Intraventricular Hemorrhage
  • Blood vessels are very fragile and rupture easily
  • No preventions to condition
  • Only treating symptoms may increase risk of IVH
  • Corticosteroids have shown to reduce risk when
    given to mother at 24 to 34 weeks prior to
    premature delivery

Preterm Birth
  • Periventricular leukomalacia
  • Contributing factors
  • Premature infant brains very fragile
  • Lack of oxygen
  • Early rupture of fetal membranes
  • Infection inside the uterus
  • No treatment for this condition

Preterm Birth
  • Cerebral palsy
  • Condition where infants are unable to control
    muscle movement
  • Muscles become tight and uncontrolled
  • No treatment for this condition
  • Necrotizing enterocolitis
  • Occurs 3 to 7 days after onset of feeding
  • Premature infants react abnormally to diet
  • Bowels become inflamed and spontaneously necrose
  • Treatment
  • Surgical treatment if bowel is perforated
  • Feedings are withdrawn
  • Contents of stomach are suctioned out

Preterm Birth
  • Retinopathy of prematurity
  • Condition where abnormal blood vessels grow
    around the eye
  • Lead to childhood blindness and reduced vision
  • Treatment
  • Laser therapy or cryotherapy
  • Burn off the abnormal vessels surrounding the
  • Cannot completely correct visual impairment
  • Only restores the sharp central vision

Developmental Outcomes for Premature Infants
  • Rate of premature births has increased
  • ? by 29 from 1981 to 2002
  • Survival rate of premature infants reaching
    adulthood has also increased
  • Can be severe consequences of prematurity
  • Cerebral palsy
  • Mental retardation
  • Visual impairments
  • Hearing impairments
  • Attention deficit hyperactivity disorder (ADHD)

Developmental Outcomes for Premature Infants
  • Prevention
  • Decrease occurrence of premature births
  • Fetal stress caused by lack of O2 during
    gestation has been linked to long term problems
  • Good maternal health
  • Avoiding cerebral injury in infants
  • Management
  • Social programs designed to assist with
  • ADHD
  • Visual and/or hearing aids for children
  • Physical therapy for movement
  • Speech, learning, hearing, and social and
    emotional development
  • Medication
  • Improve muscle spasms
  • Surgery
  • Correct bone deformities
  • Braces to improve muscle function