Labour : The process of child birth


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Childbirth, labour, delivery, birth, partus, or parturition is the culmination of a pregnancy period with the expulsion of one or more newborn infants from a woman's uterus. The process of normal childbirth is categorized in three stages of labour: the shortening and dilation of the cervix, descent and birth of the infant, and birth of the placenta.

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  • The membranes (amnion and chorion) are attached loosely to the decidua lining the uterine cavity except over the internal os. In vertex presentation, the girdle of contact of the head (that part of the circumference of the head which first comes in contact with the pelvic brim) being spherical, may well fit with the wall of the lower uterine segment.
  • Labour : The process of child birth

    2. 2. STAGES OF LABOURThere are four stages of labour. FIRST STAGE(CERVICAL STAGE): It starts fromthe onset of true labour pain and ends with fulldilatation of cervix.Its average duration is 12 hours in primigravidaeand 6 hours in multiparae.
    3. 3.  SECOND STAGE: It starts from the full dilatation of the cervixand ends with expulsion of fetus from the birth canal. Its average duration is 2 hours in primigravidae and 30 minmultiparae.SECOND STAGEPROPULSIVE PHASE EXPULSIVE PHASEStarts from the full Starts with the maternaldilatation of the cervix bearing down efforts andup to the descent of the ends with delivery of thepresenting part to the baby.pelvic floor.
    4. 4.  THIRD STAGE: Begins with the expulsion of thefetus and ends with expulsion of the placenta andmembranes.Its average duration is about 15 minutes in bothprimigravidae and multiparae.
    5. 5. FOURTH STAGE Stage of observation for atleast one hour afterexpulsion of the after births. Condition of the uterus and general condition of thepatient are carefully monitored.
    6. 6. EVENTS IN THE FIRST STAGE OFLABOUR The first stage is chiefly concerned with thepreparation of the birth canal so as to facilitateexpulsion of the fetus in the second stage. Themain events that occur are:1) dilatation and effacement of the cervix2) full formation of the lower uterine segment.
    7. 7. DILATATION OF THE CERVIX Prior to the onset of labour, in the pre-labour phase,there may be certain amount of dilatation of the cervix,especially in multiparae and in some primigravidae. PREDISPOSING FACTORS FAVOURING DILATATIONOF CERVIX : Softening of cervix Fibromusculoglandular hypertrophy Increased vascularity Accumulation of fluid in between the collagen fibers Breaking down of the collagen fibrils by collagenase andelastase. Increase in the hyaluronic acid and decrease in thedermatan sulphate levels in the matrix of the cervix.
    8. 8. FACTORS RESPONSIBLE FORDILATATION OF THE CERVIX UTERINE CONTRACTION ANDRETRACTION:The longitudinal muscle fibres of the uppersegment are attached to the circular musclefibres of the lower segment and the upper partof the cervix in a bucket holding fashion.With each contraction the canal is opened fromabove down and also becomes shortened andretracted.
    9. 9.  While the upper segment contracts, retracts and pushesthe fetus, the lower segment and the cervix dilate inresponse to the forces of contraction of the uppersegment. This coordination between the fundalcontraction and cervical dilatation is called― POLARITY OF THE UTERUS‖
    10. 10. BAG OF MEMBRANESIn vertex presentation, the girdle of contact of thehead (that part of the circumference of the headwhich first comes in contact with the pelvic brim)being spherical, may well fit with the wall of the loweruterine segment.Thus the amniotic cavity is divided into twocompartments .The part above the girdle of contactcontains the fetus with bulk of the liquor calledhindwaters and the one below it containing smallamount of liquor called forewaters.
    11. 11. BAG OF MEMBRANES
    12. 12.  With the onset of labour, the membranes attachedto the lower uterine segment are detached and withthe rise of intrauterine pressure during contractionsthere isherniation of the membranes throughthe cervical canal. Uterine contractions generate hydrostatic pressurein the forewaters that in turndilate the cervical canal like a wedge.
    13. 13. FETAL AXIS PRESSUREIn labour with longitudinal lie, straightening out of thefetal vertebral column occurs due to contraction ofcircular muscles of the body of uterus.This allows the fundal contraction to transmit throughthe podalic pole into the fetal axis, allowingmechanical stretching of the lower segment andopening up of the cervical canal.With each uterine contraction, there is elongation ofthe uterine ovoid and decrease in the transversediameter.
    14. 14. VIS-A-TERGOFinal phase of dilatation and retraction of the cervix isachieved by downward thrust of the presenting part ofthe fetus and upward pull of the cervix over the lowersegment.This phenomenon is lacking in transverse lie where athin cervical rim fails to disappear.
    15. 15. EFFACEMENT OR TAKING UP OFCERVIX Effacement is the process by which the muscularfibres of the cervix are pulled upwards and mergeswith the fibres of the lower —uterine segment. In primigravidae effacement precedes dilatation ofthe cervix, whereas in multiparae, both occurssimultaneously.
    16. 16. LOWER UTERINE SEGMENT Before the onset of labour there is no completeanatomical or functional division of uterus. Demarcation becomes pronounced with theinitiation of labour. Lower uterine segment develops from the isthmusof the( non pregnant) uterus – bounded above bythe anatomical os and below by the histological os. Formed maximally during labour .peritoneum isloosely attached anteriorly. Measures 7.5-10 cm when fully formed.
    17. 17. CLINICAL COURSE OF FIRST STAGE OFLABOUR The first symptom to appear is intermittent painfuluterine contractions followed by expulsion of bloodstained mucus (show) per vaginam. Only few drops of blood mixed with mucus isexpelled and any excess should be consideredabnormal.
    18. 18.  PAIN : The pains are felt more anteriorly withsimultaneous hardening of the uterus. Initially, the pains are not strong enough to causediscomfort and come at varying intervals of 15-30minutes with duration of about 30 seconds. Gradually the interval becomes shortened withincreasing intensity and duration so that in late firststage the contraction comes at interval of 3-5minutes and lasts for about 45 seconds. Pains are usually felt shortly after the uterinecontractions begin and pass off before completerelaxation of the uterus.
    19. 19.  Clinically, the pains are said to be good if theycome at intervals of 3-5 minutes and at the heightof contraction the uterine wall cannot be indentedby the fingers.
    20. 20. DILATATION AND EFFACEMENT OFCERVIX Cervical dilatation relates with dilatation of theexternal os and effacement is determined by thelength of the cervical canal in the vagina. in multiparae, dilatation and taking up occursimultaneously The anterior lip of the cervix is the last to beeffaced. The first stage is said to be completed onlywhen the cervix is completely - retracted over thepresenting part during contractions.
    21. 21.  Cervical dilatation is expressed either in terms offingers— 1, 2, 3 or fully dilated or better in terms ofcentimetres (10 cm when fully dilated) usually measured with fingers but recorded incentimetres. One finger equals to 1.6 cm onaverage effacement of the cervix is expressed in terms ofpercentage- 100% (cervix less than 0.25 cm thick)
    22. 22. PARTOGRAPH Freidman (1954) first devised it composite graphical record of cervical dilatationand descent of head against duration of labour inhours Cervical dilatation is a sigmoid curve . the first stage of labour has got two phases: latent phase active phase
    23. 23. PARTOGRAPH
    24. 24.  The active phase has got three components:1. Acceleration phase of cervical dilatation of 2.5-4 cm.2. Phase of maximum slope of 4-9 cm dilatation.3. phase of deceleration of 9-10 cm dilatation.In primigravidae, the latent phase is often long ,about 8hours, during which effacement occurs; the cervicaldilatation averaging only 0.35 cm/hour.In multiparae, the latent phase is short ,about 4 hours,and effacement and dilatation occur simultaneously.
    25. 25. Dilatation of the cervix at the rate of 1 cm per hour inprimigravidae and 1.5 cm in multigravidae beyond 3cm dilatation (active phase of labour), is consideredsatisfactory.
    26. 26. STATUS OF THE MEMBRANES Membranes usually remain intact until full dilatationof the cervix or sometimes even beyond, in thesecond stage. An intact membrane is best felt with fingers duringuterine contraction when it becomes tense andbulges out through the cervical opening. In between contractions, the membranes getrelaxed and lie in contact with the head. Variable amounts of liquor escape out through thevagina after the rupture of the membranes.
    27. 27. MATERNAL SYSTEM General condition remains unaffected. Feeling of transient fatigue may appear following astrong contraction. Pulse rate is increased by 10-15 beats per minuteduring contraction which settles down to itsprevious rate in between contractions. Systolic blood pressure is raised by about 10 mmHg during contraction. Temperature remains unchanged.
    28. 28. FETAL EFFECT During contractions , slowing of fetal heart rate by10-20 beats per minute occurs which soon returnsto its normal rate of about 140 per minute as theintensity of contraction diminishes.
    29. 29. EVENTS IN SECOND STAGE OFLABOUR begins with the complete dilatation of the cervix andends with the expulsion of the fetus This stage is concerned with the descent anddelivery of the fetus through the birth canal. Second stage has two phases :(A) Propulsive — from full dilatation until headtouches the pelvic floor.(B) Expulsive — since the time mother hasirresistible desire to ‗bear down and push‘ until thebaby is delivered.
    30. 30. After full dilatation of the cervix, the membranes usuallyrupture and there is escape of good amount of liquor amnii.The volume of the uterine cavity is thereby reduced.Simultaneously, uterine contraction and retraction becomestronger.The uterus becomes elongated during contraction, whilethe antero-posterior and transverse diameters are reduced.The elongation is partly due to the contractions of thecircular muscle fibers of the uterus to keep the fetal axisstraight.
    31. 31.  Delivery of the fetus is accomplished by the downward thrustoffered by uterine contractions supplemented by voluntarycontraction of abdominal muscles against the resistanceoffered by bony and soft tissues of the birth canal. Tendency to push the fetus back into the uterine cavity by theelastic recoil of the tissue of the vagina and the pelvic floor iseffectively counterbalanced by the power of retraction. With increasing contraction and retraction, the upper segmentbecomes more and more thicker with corresponding thinningof lower segment. Endowed with power of retraction, the fetus is graduallyexpelled from the uterus against the resistance offered by thepelvic floor. After the expulsion of the fetus, the uterine cavity ispermanently reduced in size only to accommodate the after-births.
    32. 32. CLINICAL COURSE OF SECOND STAGE OFLABOUR PAIN :The intensity of the pains increases.Pain comes at intervals of 2-3 minutes and lastsfor about 1-1 ½ minutes.It becomes successive with increasing intensityin the second stage.
    33. 33. BEARING DOWN EFFORTS Additional voluntary expulsive efforts that appearduring the second stage of labour (expulsivephase). Initiated by nerve reflex (Ferguson Reflex) set updue to stretching of the vagina by the presentingpart. Sustained pushing beyond the uterine contraction isdiscouraged. Slowing of FHR may occur during pushing. Itshould come back to normal once contractions areover.
    34. 34. MEMBRANES STATUS: Membranes may rupture with a gush of liquor pervaginam. Rupture may occasionally be delayed till the headbulges out through the introitus.
    35. 35. DESCENT OF THE FETUS ABDOMINAL FINDINGS: progressive descent of the head, assessed inrelation to the brim. Rotation of the anterior shoulder to the midline . change in position of the fetal heart rate - shifteddownwards and medially.o INTERNAL EXAMINATION FINDINGS: Descent of the head in relation to ischial spines. Gradual rotation of the head evidenced by positionof the sagittal suture and the occiput in relation tothe quadrants of the pelvis.
    36. 36. VAGINAL SIGNS As the head descends down, it distends the perineum,the vulval opening looks like a slit through which thescalp hairs are visible. During each contraction, the perineum is markedlydistended with the overlying skin tense and glisteningand the vulval opening becomes circular. adjoining anal sphincter is stretched and stool comesout during contraction. head recedes after the contraction passes off but is heldup a little in advance because of retraction. the maximum diameter of the head (biparietal) stretchesthe vulval outlet and there is no recession even after thecontraction passes off-CROWNING OF HEAD
    37. 37.  After a little pause, the mother experiences furtherpain and bearing down efforts to expel theshoulders and the trunk. Immediately thereafter, a gush of liquor (hindwaters) follows, often tinged with blood.
    38. 38. MATERNAL SIGNS features of exhaustion. Respiration is slowed increased perspiration face becomes congested ,neck veins becomeprominent during bearing down efforts. Immediately following the expulsion of the fetus, themother heaves a sigh of relief.
    39. 39. FETAL EFFECTS Slowing of FHR during contractions is observedwhich comes back to normal before the nextcontraction.
    40. 40. EVENTS IN THE THIRD STAGE OFLABOURThe third stage of labour comprises the stage ofplacental separation, its descent into the lowersegment and finally its expulsion with the membranes
    41. 41. PLACENTAL SEPARATIONAt the beginning of labour the placental size roughlycorresponds to an area of 20 cm in diameter.No appreciable diminution of the surface area of theplacental attachment during first stage.During second stage , slight but progressivediminution of the surface area following successiveretractions occur, and attains its peak immediatelyfollowing the birth of the baby.
    42. 42. MECHANISM OF SEPARATION OF PLACENTA Marked retraction reduces the effectively the surfacearea of the placental site to its half.Placenta being inelastic can‘t keep pace with suchan extent of diminution resulting in its debuckling.A shearing force is instituted between the placentaand the placental site which brings about the separationof the placenta from the decidua.The plane of separation runs through the spongy layer ofdecidua basalis . So variable thickness of deciduacovers the maternal surface of the separated placenta.
    43. 43. There are two ways of separation of the placenta: CENTRAL SEPARATION (SCHULTZEMETHOD):detachment of the placenta from the uterinewall attachment starts at the centre resulting in openingof a few uterine sinuses and accumulation of bloodbehind the placenta. With increasing contractions , moreand more detachment occurs facilitated by weight ofplacenta and retroplacental blood until the whole of theplacenta gets detached.
    44. 44.  MARGINAL SEPARATION (MATTHEWS- DUNCAN):separation starts at the margin as it is mostlyunsupported. with progressive uterine contraction, moreand more areas of the placenta get separated.
    45. 45. SEPARATION OF THE MEMBRANES The membranes are attached loosely in the activepart. They are thrown into multiple folds. Those attached to the lower segment are alreadyseparated during its stretching. separation is facilitated partly by uterine contractionand mostly by weight of the placenta as it descendsdown from the active part. The membranes so separated carry with themremnants of decidua vera giving the outer surfaceof the chorion its characteristic roughness.
    46. 46. EXPULSION OF THE PLACENTA After complete separation of the placenta, it isforced down into the flabby lower uterine segmentor upper part of the vagina by effective contractionand retraction of the uterus. Thereafter, it is expelled out by either voluntarycontraction of abdominal muscles (bearing downefforts) or by manual procedure.
    47. 47. MECHANISM OF CONTROL OFBLEEDING After placental separation, innumerable torn sinuseswhich have free circulation of blood from uterine andovarian vessels have to be obliterated. The occlusion is effected by complete retraction whereby the arterioles, as they pass tortuously through theinterlacing intermediate layer of the myometrium, areliterally clamped(LIVING LIGATURE). living ligature is the principal mechanism ofhaemostasis. Thrombosis also occurs which occludes the tornsinuses. This phenomenon which is facilitated by hyper-coagulable state of pregnancy. Apposition of the walls of the uterus following expulsionof the placenta (myotamponade) also contributes tominimise blood loss.
    48. 48. CLINICAL COURSE OF THIRD STAGEOF LABOURPAIN: patient experiences no pain for a short time. intermittent discomfort in the lower abdomenreappears, corresponding with the uterinecontractions.
    49. 49. BEFORE SEPARATION OF PLACENTAABDOMINAL FINDINGS: Uterus becomes discoid in shape firm in feel and non-ballottable. Fundal height slightly below the umbilicus.PER VAGINAM: slight trickling of blood
    50. 50. AFTER SEPARATION PER ABDOMEN : Uterus becomes globular, firm and ballottable. fundal height is slightly raised as the separatedplacenta comes down in the lower segment and thecontracted uterus rests on top of it. There may be slight bulging in the suprapubicregion due to distension of the lower segment bythe separated placenta.PER VAGINAM: slight gush of vaginal bleeding. Permanent lengthening of the cord is established.
    51. 51. EXPULSION OF THE PLACENTA ANDMEMBRANES Expulsion is achieved either by voluntary bearingdown efforts or aided by manipulative procedure. Followed by slight to moderate bleeding amountingto 100-250 ml.
    52. 52. MATERNAL SIGNS chills and occasional shivering. Slight transient hypotension