Labor and Delivery Flashcards
Physiology of Labor
Progesterone/estrogen/hCG
Progesterone: function is to support/stabilize the endometrium in an environment that is conducive to fetal survival and to suppress contractility in uterine smooth muscle.
Estrogen: functions are to stimulate growth of the myometrium and antagonize the myometrial-suppressive activity of progesterone, also used to stimulate the development to the mammary glands.
Chorionic gonadotropins (b-hCG): produced by fetal trophoblast cells, binds to LH receptors on the cells of the corpus luteum, which prevents luteal regression, also is the signal for maternal recognition of pregnancy.
Physiology of labor
Relaxin / Prolactin
Relaxin: Causes relaxation of pelvic ligaments, mostly at the end of gestation to prepare body for delivery.
Prolactin: stimulates the mammary gland development and milk production. Also provides positive feedback for when a woman is lactating to act as a somewhat natural form of birth control.
Physiology of labot
Oxytocin
Peptide hormone synthesized by hypothalamus and released from posterior pituitary
Also produced by the placenta
Release of oxytocin > forceful contractions
Most potent endogenous uterotonic
Circulating levels of oxytocin don’t change during pregnancy, however myometrial receptor concentrations increase in pregnancy and in labor
physiology of labor
prostagladins
Paracrine/autocrine hormones
Concentration of prostaglandins in amniotic fluid and maternal circulation are increased during parturition
Help in the onset of synchronous uterine contractions, cervical ripening, and increase myometrial sensitivity to oxytocin and increase oxytocin receptor concentrations
Phases of Parturition (labor)
UTERINE QUIESCENCE
Makes up 95% of pregnancy
Uterine smooth muscle tranquility while maintaining cervical structure and integrity
Uterine size increases, uterine vascularity increases
Myometrial contractions which do not cause cervical change (braxton hicks)
Phases of Parturition (labor)
Cervix functions in pregnancy
Cervix function in pregnancy:
1) Maintain barrier of lower vaginal tract and upper internal tract from infection
2) Maintain cervical competence despite increasing uterine size
Non pregnant women = cervix closed and firm
End of pregnancy = cervix distentable and soft
Tissue remodeling to soften the cervix
Increased vascularity, cellular hypertrophy, and collagen changes to alter strength and flexibility
Phases of Parturition
PREPARATION FOR LABOR
Progression of uterine changes during the last 6-8 weeks (uterine activation)
Myometrium prepares for labor contractions
Oxytocin receptors and prostaglandin receptors increase
Cervical ripening (Additional cervical remodeling)
Phases of Parturition
LABOR
Uterine contractions that cause cervical dilation and change
Contractions of sufficient frequency and intensity
Divided into three stages
Braxton-Hicks Contractions
False labor pains
Do not cause cervix to dilate or efface
Usually irregular in duration and intensity (lasting < 30 seconds up to 2 minutes)
Described as strong menstrual cramps
Can start around 6 weeks of gestation, but usually are not felt until 2nd or 3rd trimester
Body’s way of preparing for labor
Can be caused by:
Increased physical activity, full bladder, dehydration, after intercourse, and near the end of pregnancy
labor
When is Immediate Attention Needed?
Contractions becoming more frequent and intense (every 5 minutes or more, severe pain, not able to speak full sentences during contractions)
Vaginal bleeding
Leakage of fluid
Decreased fetal movement
definition of labor
LABOR = Regular painful uterine contractions that cause cervical dilation and effacement
cervical measurement
Cervical measurement =
Dilation / effacement / station
Cardinal Movements of Labor
engagement
descent
flexion
internal rotation
extension
external rotation (restitution)
expulsion
Types of pelvis
stages of labor
First Stage: When labor begins until 10cm dilated
Latent Stage: Slow cervical change, usually less than 1cm an hour
Active Stage: Fast cervical change, starts about 5-6cm dilated and cervix opens 1cm/hr
Second Stage: 10cm dilated until fetus delivered
Third Stage: Baby delivered until placenta delivery
First Stage of Labor: Latent vs Active Labor
LATENT
Mucus plug / Bloody show
Extrusion of mucus and blood that filled the cervical canal
Slow cervical dilation to 5cm dilated
Less than 1cm per hour
Painful irregular contractions
ACTIVE
Rapid cervical change
Painful regular contractions
Cervical dilation 1cm per hour
Spontaneous rupture of membranes
FIRST STAGE OVERALL
Nulliparous: Average 10-14hrs
Multiparous: Average 5-7hrs
labor
Cervical Exam
Dilation
How open the cervix is related to the internal cervical os
Based on digital hand exam 0-10cm
Effacement
Percent of cervix shortened
Subjective based on examiner
Normal cervix about 4cm > 2cm felt = 50% effaced
Station
Relation of the fetal presenting part to the ischial spine (-5 to +5)
Most descended part of the fetus at ischial spine = 0 station
Bishop Score
Effacement
Dilation
Station
Cervical position
In relation to the patient
Posterior / Mid position / Anterior
In labor the cervical position usually advances from posterior to anterior
Cervical consistency
Consistency of cervix- firm, medium, soft
In labor the cervix usually softens
Bishop Score > 8 is consistent with a cervix which is favorable for vaginal delivery
Spontaneous Rupture of Membranes
SROM
Check the color
Clear/yellow - generally ok
Green - meconium = first bowel movement of fetus
Dark green and thick amniotic fluid can be a sign of distress from the baby
Red - blood-tinged could be mixed with blood from cervical stretching
Bright red blood could be a sign of placental abruption