Normal Labor and Delivery

1. Normal Labor and Delivery Midwifery Division Department of OB/GYN University of North Carolina School of Medicine

2. 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

3. 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%

4. 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

5. 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

7. 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

8. 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

9. 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

11. 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)

12. Fetal Lie • Lie: relationship between the long axis of the fetus and the mother • Longitudinal • Transverse • Oblique

13. Fetal presentation • Presentation: fetal part closet to pelvic inlet • cephalic • breech • shoulder

14. Fetal position • Position: relationship of fetal presenting part to the maternal pelvis • Occiput • Brow • Mentum • Breech • Shoulder

15. Fetal Attitude • The relationship of the fetal parts to one another (i.e. flexion  extension of head relative to body).

16. Vertex Parietal Brow Face

17. (A)synclitism • Synclitism is when the biparietal diameter of the fetal head is parallel to the planes of the maternal pelvis.

19. Pelvic Exam • Pelvic Exam – sterile vaginal exam +/- sterile speculum exam • Dilation • Effacement • Station • Also position of cervix and consistency important.

20. 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”

22. 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

24. Obstetrical Pelvic Exam • Also includes same assessment included in Leopold’s maneuvers (fetal lie, presentation, position, etc.)

26. Fetal Monitoring • Intermittent • Continuous

27. Continuous Fetal Monitoring • Baseline rate • Variability • Presence of accelerations • Presence of decelerations • Changes or trends of FHR patterns over time • Contractions

28. Fetal Heart Rate Baseline • 10 minute window • Duration: at least 2 minutes • Bradycardia: < 110 bpm • Tachycardia: > 170 bpm

30. Fetal Monitoring (Variability) • Concept of short and long-term variability dropped • Absent: undetectable • Minimal: undetectable - < 5 bpm • Moderate: 6 - 25 bpm • Marked: > 25 bpm

32. 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

34. DECELERATIONSFetal Monitoring (Variables) • Onset to nadir < 30 secs • > 15 bpm below baseline • Duration: > 15 seconds • < 2 minutes from onset to return to baseline

37. DECELERATIONSFetal Monitoring (Variables) Treatment • Pelvic exam (rule out prolapsed cord) • Maternal oxygen • Change maternal position • Stop pushing • Amnioinfusion

39. Fetal Monitoring (Early Decelerations) • Onset to nadir > 30 secs • Coincident in timing with UC • Nadir occurring simultaneously with the peak of the contraction

41. Fetal Monitoring (Late Decelerations) • Onset to nadir > 30 secs • Delayed in timing • Nadir occurring after the peak of the contraction • Reccuring can be ominous

44. Fetal Monitoring(Late Decelerations) Treatment • Correct hypotension or other maternal conditions • Maternal oxygen • Scalp stimulation • Cesarean delivery if repetitive

46. Uterine Contractions External tocodynamometry Internal tocodynamometry

48. What’s going on in there? • The cardinal movements of labor are the mechanism by which the fetus moves progressively through the birth canal.

49. 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

50. 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