Mechanism of Labour and stages of labour

Labor is a physiologic process during which the fetus, membranes, umbilical cord and placenta are expelled from the uterus.

1. PRESENTED BY
MRKALYANKUMAR MSC(N)
Mechanism of Labour

2. Definition
Seriesofeventsthatoccurontheheadandthe
fetaltrunkintheprocessofadaptation,during
itsjourneythroughthepelvis.

3. Mechanism of labour
Engagement of head
Flexion of head
Internal rotation of head
Crowing
Extension and birth of head
Restitution
Internal rotation of shoulders &external rotation of head
Birth of shoulders & trunk by lateral flexion
( Descent takes place throughout birthing process)

4. First stage of labour
Itstartsfromonsetoflabourpainstothefulldilatationof
thecervix.
Latentphase:
Cervixdilatedto0-3cm
Mildandshortcontractions
Activephase:Moderatetostrongcontractions
Cervixdilatesto4-7cm
Bloodyshow
Membranesmayrupture

5. Transitionphase:Strongcontractions
Cervixdilates7-10cm
Increasedbloodyshow
Irritable,restless,emotional
Legtremors,suddennauseaandvomiting.
Duration:12hoursinprimigravida
6hoursinmultigravida.
Durationoflabourvariesandinfluencedby:-Parity,
psychologicalstate,presentation,position,pelvicshape.

6. Second stage of labour
It starts from full dilatation of the cervix to the expulsion of
fetusfrom birth canal.
Latent phase: May last upto1 hour
Decrease in frequency and increase in strength of
contractions
Active phase: Urge to push
Stronger and closer contractions

7. Transitionphase:Beginswithfetalheadonperineum;
perineumbulges.
Legcrampsarecommon.
Duration:Averagedurationisaroundonehourin
primigravidaand30minutesinmultigravida.

8. Third stage of labour
Inthisstage,theseparationandexpulsionofplacentatakes
place.
Afterdeliverysomewomenhaveshivering,aftershortinterval
discomfortinthelowerabdomenreappearsduetouterine
contractions
Beforeseparationofplacenta,fundalheightreachesbelowthe
umbilicusandtheuterusbecomesdiscoidinshape
Afterseparation,placentacomesdownintoloweruterine
segment
Thesignsofplacentalseparationare:
Suddengushofblood
Thelengthoftheumbilicalcordincreases
Duration:Averagedurationis5-15minutes.

9. Fourth stage
Thisisfromexpulsionofplacentauntil2hoursafterthe
birth.
Thisisanimportantperiodandrequiresclose
observationofthemother.Themotheriskeptinthe
deliveryroomfor1hour.Sheischeckedforbleeding,blood
pressureandpulse.

10. Summary
Conclusion