1. Normal Labor or Delivery
Chen Danqing Women’s hospital,School of medicine, Zhejiang University

2. Objective Definition of labor. Determinate Factors of Labor
Anatomical considerations:
The female pelvis.
The fetal skull.
The stages of labor.
The mechanism of labor (vertex, LOA).
Management of normal labor.

3. Definitions：Labor is the process by which contractions of the gravid uterus expel the fetus and the other products of conception after 28 weeks from the last menstrual period.
It begins when uterine contractions of sufficient intensity, frequency & duration are attained to bring about progressive effacement & dilatation of the cervix as well as descent of the presenting part.
Spontaneous or induced
Term or preterm

4. Term Delivery：A term delivery occurs between 37 and 42 weeks from the last menstrual period.
Premature Delivery：Preterm labor is that occurring before 37 weeks of gestational age.
Postdate pregnancy：Postdate pregnancy occurs after 42 weeks .

5. The etiology of labor These mechanisms are not well defined in humans.
Cervix ripend and lower uterine segment development theory；
Endocrine regulating theory；
Mechanical theory；
Neurohumor theory ；
Immunologic theory；
Maturation of fetus and change of uterus function is necessary.

6. Four Determinate Factors of Labor
The progress and final outcome of labor are influenced by 4 factors .
(1)the powers
(2)the passage
(3)the passenger
(4)the psyche

7. The Expulsive Forces(The powers)
The power that expulse the fetus and the other products of conception is called the expulsive forces, which include
♀ Uterine contraction
♀ Intra-abdominal pressure
♀Levator ani muscles contractions.

8. Have three unique characteristics:
Uterine Contractions
Have three unique characteristics:
★Rhythm: increase in frequency and duration,is the important marker of in labor。rhythm
★ Symmetry and polarity Symmetry and polarity
★ Retraction Retraction

9. Rhythm Increase in frequency and duration
Periods of relaxation between contractions are essential to the welfare of the fetus. 极期 进行 退行 宫缩
间歇期 宫缩

10. The intensity of the upper segment of the uterus is the most strong
Symmetry and Polarity
The intensity of the upper segment of the uterus is the most strong

11. The Intra-Abdominal Pressure
＆It is a necessary auxiliary to uterine contractions in second stage of labor.
＆After the placenta has separated, its spontaneous expulsion is aided by the mother increasing intra-abdominal pressure.

12. 腹肌
子宫收缩力 膈肌
肛提肌

13. Levator ani muscles contractions
※ Form a V-shaped sling that tends to rotate the occipital anteriorly(internal rotation).
＆ Help the fetus’ extension and delivery.
＆Help the expulsion of the placenta.

14. Passage including: the bony pelvis and soft tissues of pelvis
True vs. false pelvis.
True pelvis:
Pelvic brim.
Pelvic cavity.
Pelvic outlet.

15. bony pelvis 髂 骨 骶 骨 os ilium Os sacrum 骶 尾 关 节 尾 骨 Sacro-iliac jiont
髂 骨
os ilium
骶 骨
Os sacrum
骶 尾 关 节
Sacro-iliac jiont
尾 骨
Os coccyx
耻骨联合
Symphysis publis
坐骨结节
Os ischium

16. The bony pelvis (the true pelvis)
Pelvic inlet plane
Pelvic midplane
Pelvic outlet plane
Three pelvic plane:

17. The Pelvic Inlet Shape: Boundaries: Dimensions: Oval & in one plane.
Anteriorly: SP.
Laterally: upper margin of pubic bone & iliopectineal line.
Posteriorly: sacral promontory.
Dimensions:
AP=11 cm Transverse=13.5 cm.

18. The true conjugate
The inclined diameter
The transverse diameter

20. Three anteroposterior diameters of the pelvic inlet

21. Pelvic Midplane
The smallest plane of the pelvis, particular importance in obstructed labor.
Anteroposterior diameter of mid pelvis,average 11.5cm.
Transverse diameter of mid pelvis,alse be called interspinous diameter,average 10cm.

22. Anteroposterior diameter of mid pelvis
Transverse diameter of mid pelvis

23. Transverse diameter of the midpelvis

24. Pelvic Outlet Plane Four diameters,
Anteroposterior, diameter of outlet, 11.5cm。
Transverse outlet, the distance between the inner edges of the ischial tuberosities,9cm
Anterior sagittal diameter,6cm
Posterior sagittal diameter,8.5cm

25. 1、Transverse outlet
2、 Anterior sagittal diameter
3、 Posterior sagittal diameter
4、 Anteroposterior diameter of outlet 4

27. Pelvic axis and Inclination of pelvic
Pelvic axis：The axis of the pelvis refers to the curve of the birth canal as described by a line drawn through the center of each of the four planes.
Inclination of pelvic :The angle of the pelvic inlet plane with ground level when women stand.always 60 degree.

28. pelvic axis
inclination of pelvic
骨盆轴

31. The Soft Part of the Birth Canal
Formation of lower uterine segment,cervix, vagina,soft tissue in the floor of pelvis.

32. The Lower uterine segment
Developed from the isthmus of the uterus of nonpregnant women.
Physiologic retraction ring : The actively contracting upper segment becomes thicker as labor advances,the lower uterine segment is relatively thin compared with the upper segment,between them a physiologic retraction ring appear.

34. Changes of cervix Effacement of cervix
The upper segment contracts, retracts, and expels the fetus; in response to the force of the contractions of the upper segment, the ripened lower uterine segment and effacement of cervix.

36. Dilatation of Cervix
In response to the force of the contractions of the upper segment, effacement of cervix and dilatation, through which the fetus can be extruded.

37. Change of cervix during labor
Effacement of cervix
dilatation of cervix
primigravida
9 100% successful
% successful
% successful
multipara

38. A crook canal formed by the vagina、tissue of pelvic floor and perineum as the fetal descending.

39. Passenger Fetus(weight,position,presentation, malformation)
Fetal weight, 2500g - <4000g
Fetal lie, the relation of the fetal long
axis to that of the mother.
Fetal presentation, the presenting
part is either foremost within the birth
canal or in closest proximity to it.LOA
LOP LOT ROA ROP ROT

40. Size of the fetus head Very important for delivery。
The vault is composed of 2 frontal bones,2 parietal bones, 2 temporal bone and one occipital bone.
They are slightly separated from one another at the margins of abutment and by wider spaces, the anterior and posterior fontanelles.

41. Four diameter of fetus head：
Biparietal diameter,The greatest transverse diameter of the head,which extends from one parietal bone to other.
Average 9.3cm.
Occipito-frontal diameter：Which follows a line extending from a point just above the root of the nose prominent portion of the occipital bone. Average 11.3cm.

42. Suboccipito-bregmatic diameter.
Which follows a line drawn from the middle of the large fontanel to the undersurface of the occipital bone just where it joins the neck. Average 9.5cm
Occipito-mental diameter：From the chin to the most prominent portion of the occiput. Average 13.3cm

43. Suboccipito-bregmatic
occipito-frontal
Occipito-mental diameter

45. Position of the fetus
Fetal position of a particular presentation refers to the relationship of an arbitrary reference point on the fetus to a specific point in the right or left side of the maternal pelvis.

46. Psychologic Factors
A high level of anxiety during pregnancy has been associated with decreased uterine activity and with longer and dysfunctional labor。

47. Mechanism of Labor
Mechanism of normal labor in occiput presentation include these cardinal movements of labor.
engagement
descent
flexion
internal rotation
Extension
external rotation,and expulsion.

48. Engagement The mechanism by which the biparietal diameter,the greatest transverse diameter of the fetal head in occiput presentations,passes through the pelvic inlet is defined engagement.

49. Descent
Descent continues progressively until the fetus is delivered;the other movements are superimposed on it.

50. Flexion
In flexion,the chin is brought into more intimate contact with the fetal thorax,and the appreciably shorter suboccipitobregmatic diameter(9.5cm) is substituted for the longer occipitofrontal diameter(11.3cm).

51. Internal rotation
Internal rotation is a turning of the fetus occiput gradually moves from its original position anteriorly toward the symphysis pubis about 45 degrees. It’s always finished in the end of the first stage of labor.

52. Extention
Extention brings the base of occiput into direct contact with the inferior margin of the symphysis pubis.

53. Restitution External rotation
The fetus head rotates to the position it occupied at engagement after it deliveried, following this the shoulders descend in a path similar to that traced by the head.
External rotation
The anterior shoulder rotates internally about 45 degrees to come under the pubic arch for delivery.The head continutly rotates left about 45 degrees to its position at birth.

54. Flowing these maneuvers, the body,legs,and feet are deliveried.

55. Diagnosis of labor Threatened labor False labor:
Contractions occur at irregular intervals.
Intervals remain long.
Intensity remains unchanged.
Discomfort is chiefly in lower abdomen.
Cervix does not dilate.
Discomfort is usually relieved by sedation.

56. Lightenting
The settling of the fetal head into the brim of the pelvis.
Bloody Show
The mucus plug is expelled from the cervix mixing with a little blood.

57. In labor
Onset of labor is spontaneous uterine contraction with progressive dilation of the cervix
uterine contraction
interval < 5 ’
lasting >30’’
intensity is middle or heavy

58. Duration of Labor and Satges
The total stage of labor begins with the regular uterine contractions and ends when delivery of the placenta complete.
Normal labor is a continuous process which has been divided into three stages for purposes of study.

59. First stage of labor
The first stage begins with the onset of labor and ends when dilation of cervix (10cm) is complete.
The average duration of the first stage of labor in a primigravida is hours;in a multipara 6-8 hours.
Clinical finding:
Rhythm contraction
Cervical dilation
Descend of presentation
Rupture of membranes

60. Clinical course and treatment in first stage Contraction
Dilation of cervix and decent of presentation
the latent phase ( onset to <3cm, <16h)
the active phase(>3cm to 10cm, <8h)
Rupture of membranes

61. Management of the first stage:
⊙Blood pressure、 fetal heart rate 、cervical dilation、fetus descending、uterine contraction；
⊙ When the membranes ruptured,please check the fetal heat rate,fluid colour and amount at once
Fetal heart rate 120～160bpm
latent stage 1～2h fetal heat rate
active stage minute
⊙ Need for subsequent vaginal examinations to identify the status of the cervix and the station and position of presenting part will vary considerably.

62. Second stage of labor Third stage of labor
The second stage of labor extends from full dilation of the cervix to the birth of baby and varies from a few minutes to about two hours depending on both fetal and maternal factors primigravida <2h
multipara <1h
Third stage of labor
From the birth of the infant to delivery of the placenta 5－15min, <30min

63. Management of the second stage
■Fetal heart rate: should be measured at least every 5～10min.
■ Maternal expulsive efforts.
■ Preparation for delivery
primigravida from cervical dilation completed
multipara from cervical dilation 4cm

64. Management of third stage of labor. Clinical course
After delivery of the infant,the height of the uterine fundus and its consistency are ascertained.
Uterine contraction reappear after stopping for few minutes.
Placental separation

65. Signs of placental separation：
a.the uterus becomes globular and firmer.
b.The umbilical cord lengthened outside the vagina
c.A fresh show of blood from vagina
d.the uterus fundus rises up.

66. Pay attention to: Examine the placenta to ensure complete removal.
Examine the soft part of the birth canal.
Prevention of excessive postpartum bleeding.
Uterine contraction 、bladder distension

67. thankyou