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Normal Labor and Delivery. Midwifery Division Department of OB/GYN University of North Carolina School of Medicine. OBJECTIVES. Define labor and its stages Exam of the laboring woman and her fetus Review the cardinal movements of labor and birth Review Disorders of Labor
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Normal Labor and Delivery Midwifery Division Department of OB/GYN University of North Carolina School of Medicine
OBJECTIVES • Define labor and its stages • Exam of the laboring woman and her fetus • Review the cardinal movements of labor and birth • Review Disorders of Labor • Induction of Labor • Other labor issues
Define Labor and its Stages • Labor: progressive change of the cervix in the setting of uterine contractions • Term Labor: > 37 weeks gestation • Preterm Labor: < 37 weeks gestation • 11% of all US births in 1997 • 80% of preterm births between 34 - 36 weeks • Preterm delivery < 35 weeks: 3.5%
Define Labor and its Stages • Stages of Labor • 1st stage – onset of labor until full cervical dilitation • 2nd stage – from full dilitation to birth of infant • 3rd stage – from birth of infant until delivery of placenta • 4th stage – 2 hours after the delivery of placenta
Define labor and its Stages1st stage and its phases • Latent phase: onset of contractions until active phase • Active phase: 3 cm dilation in nulliparas; 4 cm dilation in multiparas to deceleration phase • Deceleration phase: 8 – 9 cm dilation to complete dilation
Exam of the Laboring woman and her Fetus • Review of prenatal records and labs • Physical exam • 1. Vitals and routine physical exam • 2. Abdominal Exam • Palpation of contractions • Leopold’s maneuvers • 3. Pelvic Exam • 4. Fetal heart rate monitoring
Review of Prenatal Records • Allergies • Medications • Past medical, surgical, obstetrical, gynecologic, social and family histories • Routine prenatal lab work • Complications of current or past pregnancies
Abdominal Exam • 1. Palpation of contractions for duration and intensity • 2. Leopold’s maneuvers • To assess estimated fetal weight, fetal lie, presentation and position, attitude, and (a)synclitism
NORMAL LABOR & DELIVERYEstimated Fetal Weight • Leopold’s maneuvers (palpation of the maternal abdomen) • Ultrasound estimate of fetal weight (error of 10 – 15%) • Maternal estimate of fetal weight (best)
Fetal Lie • Lie: relationship between the long axis of the fetus and the mother • Longitudinal • Transverse • Oblique
Fetal presentation • Presentation: fetal part closet to pelvic inlet • cephalic • breech • shoulder
Fetal position • Position: relationship of fetal presenting part to the maternal pelvis • Occiput • Brow • Mentum • Breech • Shoulder
Fetal Attitude • The relationship of the fetal parts to one another (i.e. flexion extension of head relative to body).
Vertex Parietal Brow Face
(A)synclitism • Synclitism is when the biparietal diameter of the fetal head is parallel to the planes of the maternal pelvis.
Pelvic Exam • Pelvic Exam – sterile vaginal exam +/- sterile speculum exam • Dilation • Effacement • Station • Also position of cervix and consistency important.
Obstetrical Pelvic Exam • Dilation (dilatation): patency of the internal cervical os • 0 = “closed” • 10 cm = “complete” • Effacement: shortening of the cervical length • 0% = “thick” • 100% = “fully effaced”
Obstetrical Pelvic Exam • Station: level of presenting part (bony portion) in relation to the maternal ischial spines • Ischial spines = O station • Above spines: -5 to -1 • Below spines: +1 to +5
Obstetrical Pelvic Exam • Also includes same assessment included in Leopold’s maneuvers (fetal lie, presentation, position, etc.)
Fetal Monitoring • Intermittent • Continuous
Continuous Fetal Monitoring • Baseline rate • Variability • Presence of accelerations • Presence of decelerations • Changes or trends of FHR patterns over time • Contractions
Fetal Heart Rate Baseline • 10 minute window • Duration: at least 2 minutes • Bradycardia: < 110 bpm • Tachycardia: > 170 bpm
Fetal Monitoring (Variability) • Concept of short and long-term variability dropped • Absent: undetectable • Minimal: undetectable - < 5 bpm • Moderate: 6 - 25 bpm • Marked: > 25 bpm
Fetal Monitoring (Accelerations) • Onset to peak: < 30 seconds • > 32 weeks: >15 bpm X >15 secs • < 32 weeks: > 10 bpm X > 10 secs • > 2 minutes in duration: prolonged • > 10 minutes in duration: change in baseline
DECELERATIONSFetal Monitoring (Variables) • Onset to nadir < 30 secs • > 15 bpm below baseline • Duration: > 15 seconds • < 2 minutes from onset to return to baseline
DECELERATIONSFetal Monitoring (Variables) Treatment • Pelvic exam (rule out prolapsed cord) • Maternal oxygen • Change maternal position • Stop pushing • Amnioinfusion
Fetal Monitoring (Early Decelerations) • Onset to nadir > 30 secs • Coincident in timing with UC • Nadir occurring simultaneously with the peak of the contraction
Fetal Monitoring (Late Decelerations) • Onset to nadir > 30 secs • Delayed in timing • Nadir occurring after the peak of the contraction • Reccuring can be ominous
Fetal Monitoring(Late Decelerations) Treatment • Correct hypotension or other maternal conditions • Maternal oxygen • Scalp stimulation • Cesarean delivery if repetitive
Uterine Contractions External tocodynamometry Internal tocodynamometry
What’s going on in there? • The cardinal movements of labor are the mechanism by which the fetus moves progressively through the birth canal.
Cardinal Movements of Labor – Occurring during first and second stages of labor • Engagement: descent of biparietal diameter to the level of the ischial spines (0 station) • Often occurs before onset of labor in nulliparous patients • Descent • Flexion: presenting diameters of fetal head presenting to maternal pelvis are optimized
Cardinal Movements of Labor • Internal rotation: fetal occiput rotates from transverse to AP • Extension: head rotates under symphysis pubis • External rotation (restitution): occiput and spine assume same position • Expulsion: fetal body delivers