Introduction to Normal Labour
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This document provides information about normal labor, including definitions, objectives, factors affecting normal labor, signs of onset, and the stages of labor. It defines labor as the process of expelling the fetus through the birth canal after viability. The four objectives are to define normal vs abnormal labor, explain factors affecting normal labor, distinguish the signs of onset, and identify the stages of labor. It describes the three main factors as power (uterine contractions), passage (changes in uterus, cervix, etc.), and passenger (fetus). It also outlines the signs of onset such as lightening, cervical changes, and false vs true labor pains. Finally, it explains the four stages of labor in detail including first stage cervical dilation, second
Introduction to Normal Labour
- 1. Normal labor Presented By Heera KC MSc. Nursing 2nd year Maternal Health Nursing 1/13/2019 1
- 2. Objectives • Define labour, normal and abnormal labor. • Explain the factors affecting normal labour. • Explain the premonitory signs of labor. • Distinguish the difference between true and false labour • State the causes of onset of normal labour. • Identify the stages of labour. 1/13/2019 2
- 3. Labor • “Labour is the physiological process by which fetus, placenta and membranes are expelled through the birth canal after viability (22nd week of pregnancy).” WHO • Series of events that take place in the genital organs in an effort to expel the viable product of conception out of the womb through the vagina into the outer world is called labor. 1/13/2019 3
- 4. Labor may be • Spontaneous or induced • Term or preterm Preterm labor – Prior to 37 weeks Term – 37 to 42 weeks Post term – After 42 weeks Post dates – After 40 weeks 1/13/2019 4
- 5. Terminologies • Parturiant : is a patient in labor and • Parturition : is the process of giving birth. • Delivery: is expulsion of the viable fetus out of the womb/ uterus. It is not synonymous with labor; delivery can take place without labor as in elective caesarean section. Delivery may be vaginal, either spontaneous or aided or it may be abdominal. 1/13/2019 5
- 6. NORMAL LABOR (EUTOCIA) • Physiological process by which the fetus, placenta and membrane are expelled through birth canal after full term of of pregnancy. 1/13/2019 6
- 7. Criteria of Normal Labour • Spontaneous in onset and at term. • With vertex presentation. • Without undue prolongation. • Natural termination with minimal aids. • Without having any complication affecting the health of the mother and or the baby. 1/13/2019 7
- 8. Factors affecting normal labour Psychological response 1/13/2019 8 Passage Power Passenger Position
- 9. Power Primary power: Involuntary uterine contraction • Responsible for effacement and dilation of cervix 1/13/2019 9 Secondary powers Contraction changes to expulsive. Voluntary bearing down of mothers. No efforts in cervical dilation. Primary and secondary force to expel fetus.
- 10. Passage • Soft tissue passage: change in uterus, cervix, vagina , pelvic floor • Bony Passage: true pelvis, outlet 1/13/2019 10
- 11. Passanger • Fetus, placenta, membrane, liquor amnii, cord. • The passage of fetus is determined by various factors: the size of the fetal head, fetal presentation, fetal lie, fetal attitude 1/13/2019 11
- 12. Position of a labouring women • Frequent change in position relief fatigue, increase comfort and improve circulation. • An upright position (walking, sitting, kneeling or squatting offers a number of advantage. • If women wishes to lie down left lateral position is suggested. 1/13/2019 12
- 13. Abnormal Labour (Dystocia) • Any deviation from the normal labour is called abnormal labour. • Fetal presentation other than vertex or having some complications even with vertex presentation affecting the course of labour or modifying the nature of termination or adversely affecting the maternal and fetal prognosis is called an abnormal labour. 1/13/2019 13
- 14. Signs and symptoms of onset of spontaneous normal labor • Lightening • Cervical changes • Appearance of false pain • Taking up of the cervix 1/13/2019 14
- 15. Lightening • This is sinking of the presenting part into the true pelvis, which takes about 2-3 weeks before onset of labor in primigravida and during onset of labor in multigravida. • It is due to the active pulling up of the lower pole of the uterus around the presenting part. • It signifies incorporation of the lower uterine segment into wall of the uterus, it may be gradual process or may be felt abruptly. 1/13/2019 15
- 16. Lightening • This diminishes the fundal height and hence minimizes the pressure on the diaphragm. • The mother experiences a sense of relief from the mechanical cardiorespiratory problems. • Breathing is easier, the heart and the stomach can function better and the relief experienced by the women is described as lightening. 1/13/2019 16
- 17. Showing phenomenon of “lightening”. (A) Before and (B) after lightening (A) (B)
- 18. CERVICAL CHANGES • A ripe cervix is (a) soft, (b) 80% effaced (<1.5 cm in length), (c) admits one finger easily, and (d) cervical canal is dilatable. 1/13/2019 18
- 19. APPEARANCE OF FALSE PAIN • Erectile and irregular pain, causing the uterus to contract and relax, where as in the labor the uterus contract and retracts regularly. 1/13/2019 19 TAKING UP OF THE CERVIX Taking up of the cervix occurs because it is being and merged into the lower uterine segment.
- 20. Taking up of the cervix
- 21. False labour pain (spurious labour) • Period of irregular (but sometimes) regular contractions that occur without progressive cervical dilation. • Contractions usually do not progress in their frequency, duration or intensity. • Usually appears prior to the onset of true labor pain by one or two weeks in primigravida and by few days in multipara. • Found more in primigravida than multigravida women. 1/13/2019 21
- 22. Characteristics • Dull in nature and usually confined to the lower abdomen and groin. • Continuous and unrelated with hardening of the uterus. • Without any effect on dilatation of the cervix. • Pain relives by use of sedatives and position changes. 1/13/2019 22
- 23. True labour pain • Onset of regular uterine contractions (pain) that become more frequent and forceful in later weeks of pregnancy characterized by: 1. Painful uterine contractions with regular interval and increasing intensity (labour pain) 2. Appearance of show 3. Progressive effacement and dilatation of the cervix. 4. Formation of the ‘bags of waters’ 1/13/2019 23
- 24. Appearance of show Dilatation of internal os
- 25. Formation of bag of water
- 26. S.no Features True labour False labour 1 Painful uterine contraction Regular Irregular 2 Interval between pain Gradually shortens Remains long 3 Intensity Increases Same 4 Site of pain Back and abdomen Chiefly lower abdomen 5 Cervical dilatation and effacement Present Absent 6 Bulging of fore water Present Absent 7 Sedation and enema Pain not stopped Usually relieved 8 Show Usually present Absent Difference between false and true labour
- 27. THEORIES AND CAUSES OF ONSET OF LABOR • Mechanical factors • Hormonal factors (endocrine) • Neurological factors 1/13/2019 27
- 28. ↑ Uterine activity Mechanical stimulation Overstretching of the uterus and pressure of presenting part on the lower segment Mechanical factors
- 29. Hormonal factors 1/13/2019 29 Cascade of events activates the fetal hypothalamic pituitary adrenal axis prior to the onset of labour. Feto-placental contribution
- 30. 1/13/2019 30 Hormonal factors Cont…
- 31. Uterine contraction ↑ Production of oestrogen and prostaglandin from placenta ↑ cortisol secretion from fetal adrenal ↑ Fetal adrenal activity ↑ release of adrenocorticotrophic hormone ↑ corticotrophic Releasing hormone Fetal hypothalamic pituitary adrenal axis stimulated prior onset of labour
- 32. ESTROGEN Theory MODE OF ACTION Increase prostaglandin synthesis Increase myocardial contractile protein Increase excitability of myometrial cell membrane Promotes synthesis of receptors for oxytocin in the myometrium and decidua Release of oxytocin from maternal pituitary HORMONAL FACTORS Cont…
- 33. ↑ fetal production of dehydroepiandrosterone sulphate and cortisol inhibit the conversion of fetal pregnenolone to progesterone Decrease Progesterone synthesis Alteration of oestrogen, progesterone ratio Increase Uterine contraction HORMONAL FACTORS Cont… Progesterone During pregnancy, inhibits myometrial contraction, but in late pregnancy
- 34. Myometrial contractile system Enhances gap junction, Increase of oxytocin receptors in decidua ↑ Prostaglandin (from placenta, fetal membranes, decidual cells and myometrium) Hormonal theory cont…Prostaglandin
- 35. Prostaglandin synthesis is triggered by • Rise In Oestrogn Level, • Glucocorticoids, • Mechanical Stretching In Late Pregnancy, • Increase In Cyotokines, 1/13/2019 35 • Infection, • Vaginal Examination, • Rupture of the Membrane.
- 36. Oxytocin theory • Oxytocin receptors are present in the uterus; they increase in uterus with the onset of labour. • It promotes the release of prostaglandins from the decidua. • Vaginal examination and amniotomy cause rise in maternal plasma oxytocin level (Ferguson reflex). • Oxytocin level reach maximum at the moment of birth. 1/13/2019 36
- 37. 1/13/2019 37
- 38. 3. Neurological factors • Labor may also be initiated through the nerve pathways. • α and β adrenergic receptors are present in the myometrium. • Estrogen acts on the α and progesterone acts on the β . • The contractile response is initiated through the α receptors of the postganglionic nerve fibers in and around the cervix and lower part of the uterus. 1/13/2019 38
- 39. STAGES OF LABOR 1. First stage of labour 2. Second stage of labour 3. Third stage of labour 4. Fourth stage of labour 1/13/2019 39
- 40. 1/13/2019 40
- 41. 1/13/2019 41 Cervical dilatation Expulsion after birth
- 42. 1/13/2019 42 Expulsion after birth
- 44. Third stage of labour • Is referred as placental stage. • It begins after the birth of the baby and ends with the expulsion of placenta and membrane. • Uterine contraction decreases basal blood flow, results in thickening and reduction in the surface area of the myometrium underlying the placenta with subsequent detachment of the placenta. • The average time duration is 15-30 minutes, but could be reduced up to 5 min. by active management of third stage of labour. 1/13/2019 44
- 45. Fourth stage of labour • It is the stage of observation for at least one hour after expulsion of the placenta and membranes. • During this period, general condition of the patient and the behavior of the uterus and bladder are to be observed carefully. 1/13/2019 45
- 46. 1st Stage 2nd Stage 3rd Stage 4th Stage Latent phase Active phase Transition al phase Propulsive phase Expulsive phase Primi Total 6-8 hrs 6 hrs 1-2 hrs 1- 2 hrs 15-30 min 1 hr 11-12 hrs 3/4 hr 15-30 min 1 hr Multi Total 4 hrs 30min -1 hr 5- 30 min 15-30 min 1 hr 6 ½ hrs 1/4 hrs 15-30 min 1 hr Duration of labor
- 47. First stage of labor • Starts from the onset of true labor pain and ends with full dilation of cervix. • Is the longest and most variable stage. • Also called as cervical stage or dilation stage of labor. • Its average duration is 11-12 hrs in primigravida and 6-8 hrs in multigravida. 1/13/2019 47
- 48. 3 sub-stages • Latent phase (early)-: mild intensity and cervix dilates from 0 to 4 cm. • Active phase:- mild to moderate intensity and cervix dilates from 4 to 7 cm. • Transitional phase:- moderate to strong intensity and the cervix dilates from 8 to 10 cm. 1/13/2019 48
- 49. Contractions Latent phase Active Phase Transitional Phase Frequency 10 – 15 minutes 2 – 5 minutes 2-3 minutes Duration 15-20 seconds 20-40 seconds more than 40 seconds Intensity Begin Mild and become moderate Begin moderate and become strong strong ………………… … At every 10 minutes interval, assess the contraction as:
- 50. (Sign and symptoms) Clinical course of 1st stage of labour • Painful uterine contraction • Progressive dilatation and effacement of the cervix. • Status of the membrane • Maternal effect • Fetal effect 1/13/2019 50
- 51. PAIN • Felt more anteriorly with simultaneous hardening of the uterus. Initially, come at varying intervals of 15–30 minutes with duration of about 30 seconds. • But gradually the interval becomes shortened with increasing intensity and duration. • In late first stage the contraction comes at intervals of 3–5 minutes and lasts for about 45 seconds. • In normal labor, pains are usually felt shortly after the uterine contractions begin and pass off before complete relaxation of the uterus. 1/13/2019 51
- 52. DILATATION AND EFFACEMENT OF THE CERVIX • Cervical dilatation relates with dilatation of the external os. • Effacement (thinning) is determined by the length of the cervical canal in the vagina. • In primigravidae, the cervix may be completely effaced, feeling like a paper although not dilated enough to admit a fingertip. • While in multiparae, dilatation and taking up occur simultaneously which are more abrupt following rupture of the membranes. 1/13/2019 52
- 53. DILATATION AND EFFACEMENT OF THE CERVIX • The anterior lip of the cervix is the last to be effaced. • The first stage is said to be completed only when the cervix is completely retracted over the presenting part during contractions. • Dilatation of the cervix at the rate of 1 cm/h in primigravidae and 1.5 cm in multigravidae beyond 4 cm dilatation (active phase of labor) is considered satisfactory. 1/13/2019 53
- 54. DILATATION AND EFFACEMENT OF THE CERVIX • Cervical dilatation - expressed either in terms of fingers—1, 2, 3 or fully dilated or in terms of centimeters (10 cm when fully dilated). • It is usually measured with fingers but recorded in centimeters. • One finger equals to 1.5 cm on average. 1/13/2019 54 Effacement of the cervix is expressed in terms of percentage, i.e. 25%, 50% or 100% (cervix less than 0.25 cm thick). The term “rim” is used when the depth of the cervical tissue surrounding the os is about 0.5–1 cm
- 55. STATUS OF THE MEMBRANES • Usually remain intact until full dilatation of the cervix or sometimes even beyond in the second stage. • May rupture any time after the onset of labor but before full dilatation of cervix- early rupture. • Premature rupture • Tensed and bulged in contraction,in between contractions, the membranes get relaxed and lies in contact with the head • Acceleration of uterine contractions – when ruptured. 1/13/2019 55
- 56. MATERNAL SYSTEM 1/13/2019 56 Fatigue Changes in pulse rate and BP FETAL EFFECT During contraction, there may be slowing of fetal heart rate by 10–20 beats per minute which soon returns to its normal rate of about 140 per minute as the intensity of contraction diminishes.
- 57. • D.C.,Dutta’s.(2004) Textbook of obstetrics.8th Edition. New central Book Agency. • Fraser, DM. , Cooper, MA.(2006) Myles Textbook for Midwives .14th edition. Churchill Livingstone. • Roshani,T. ,(2005) Mannual of Midwifery B.3rd Edition. Vidyarthi Pustak Bhandar. • Subedi, D., Gautam, S.,(2011) Midwifery Nursing part II. 2nd edition. Medhavi Publication. References
Editor's Notes
- #34: Progesterone metabolism in fetal membranes decreases at term