LABOUR in obstetrics and Gynaecology course

This ppt gives an insight on labor and it will help you to develop a bit of some skills in the labor ward.

1. LABOUR Ms. Mulusa

2. Introduction The transition from pregnancy to labour is a sequence of events that begin gradually. Women should have adequate knowledge prior to labour to ensure comprehension of changes labour will bring. The complex physical, psychological and emotional experience of labour affects every woman differently, therefore midwives must have sound knowledge as well as a range of different experiences to ensure the woman has some control over the birth of her baby.

3. DEFINITIONS LABOUR Labour is the process whereby a viable fetus, placenta and membranes are expelled from the uterus through the birth canal (Ngoma, 2003).

4. NORMAL LABOUR Labour is said to be normal when it is spontaneous in onset and occurs at term with the fetus in vertex presentation , the process completed within 16 hours without any complications to the mother or baby.

5. Causes of onset of labour Normal labour occurs after 38 th week of gestation. By this time the fetus is mature and ready for birth. The exact cause of onset of labour is not known, but it is believed that there are several complex factors that precipitate labour and these interact with each other. These factors are; Hormonal Mechanical

6. Hormonal There is evidence that something triggers the fetal hypothalamus to produce releasing factors which stimulate the Anterior Pituitary Gland to produce adrenocorticotrophic hormone (ACTH). This ACTH stimulates fetal adrenal glands to secrete cortisol and androgens. These hormones stimulate the placenta to secrete its eostrogenic and relaxin hormones . The decreased availability of progesterone towards the end of pregnancy causes a sharp rise in oestrogen, resulting in uterine fibres to display oxytocic receptors.

7. Cont’d Oestrogen also stimulates the placenta to release prostaglandins that induce production of enzymes that will digest collagen in the cervix, helping it to soften. Oxytocin is released from the maternal posterior pituitary gland which maybe due to the changing estrogen- progesterone ratio. Oxytocin stimulates the release of prostaglandins from the myometrium and in turn sensitizes the contractile response. The stimulation of the cervix leads to increased release of oxytocin.

8. Cont’d Prostaglandins are E2 and F2 initiate myomentrial contractions hence labour commences by acting as the cell messa n ger to the smooth muscle of the uterus to contract. Prostaglandins are released by the lysosomes of the decidual and myometrium cells.

9. Cont’d This hormone facilitates the entry of calcium into the cells which in turn sensitize the myometrium to oxytocin. These multiple effects stimulate the uterus to contract

10. Cont’d Both oxytocin and prostaglandins cause uterine contractions. The fall of progesterone is significant because this hormone is thought to have an inhibiting effect on muscle contraction.

11. Mechanical Uterine activity also results from mechanical stimulation of the uterus and cervix where they become sensitive due to over distension of the uterus. This suggest that the nerve endings or receptors in the uterine muscle are stimulated once the uterine contents are large enough but does not account for all onset of labours. This may be brought about by overstretching as in the case of a multiple pregnancy or pressure from a presenting part which is well applied to the cervix stimulate the nerve endings in the cervix.

12. FACTORS INFLUENCING THE Process OF LABOUR There are four important factors that have a bearing on the progress of labour. These are; the passage, passenger, powers and psychological preparedness of the mother.

13. 1.The passage The maternal bony pelvis (true pelvis), the muscles of the pelvic floor and the perineum forms the passage through which the fetus must pass during labour and delivery.

14. 2. The passenger The passenger includes fetus, placenta, membranes, cord, liquor and amnion. The state of the passenger determines the outcome of labour.

15. 3.The powers The powers of labour are divided in two i.e. primary and secondary powers. Primary powers are the contraction and retraction of uterine muscles in all three stages of labour. Secondary powers are the abdominal muscles and diaphragm which are used to increase the expulsive bearing down effort of the second stage of labour.

16. 4. Psychological preparation The woman’s psychological preparation plays an important role in the progress of labour. Many women may fear the pain of contractions and worry about the ability to withstand this pain. Teachings about the process of labour during antenatal care may help reduce anxieties and fears in some women. The presence of a support person such as spouse or family member may also reduce anxiety and promote comfort and confidence in the woman

17. Differences between true and false labour The following are the signs of false labour; False labour is common in multiparous women. The contractions often occur at night. The abdominal pain which the woman experiences during contractions is much intense than would be expected for the strength and the duration of the contractions However, backache is seldom experienced.

18. The contractions are erratic and irregular in frequency and in duration and last both longer and shorter periods than true labour . And on vagina examination the cervix may not be favourable that is the cervix may be hard and not soft or ‘ripe’ the cervical canal is not effaced or taken up hence no dilatation of the cervix.

19. TRUE SIGNS OF LABOUR 1 ) Painful rhythmic uterine contractions these contractions and characterized by tightening, discomfort, actual pain felt, uterine feels hard to touch, contractions are more frequent and longer and felt in the abdomen. 2.) Show discharge of blood stained mucus from the cervical mucosa. 3). Shortening and dilation of the cervical os This is the widening of the cervix to permits passage the fetal head usually results in the dilation of os depends on the pressure of the presenting part.

20. Cont’d 4 .Formation of the bag of waters. This is formed by bulging of the membranes into the cervical canal which has dilated easily felt during the contraction

21. Summary of differences Sig n True labor False labor Contractions Contractions are usually of regular intervals. Intervals between contractions gradually shorten Contractions increase i n duration a n d intensity Contractions are usually intensified b y walking Contractions are irregular Usually n o change Usually n o change Walking has no effect on contractions Discomfort Begins i n the back a n d radiates to the abdomen Discomfort is usually in the abdomen Cervical effacement a n d dilatation Prese n t a n d progressive N o cervical dilatation

22. Cont’d Sign True labor False labor Show Prese n t Absent Formation of the b ag of waters Present Present

23. Changes during the last weeks of pregnancy During the last few weeks of pregnancy, the following physical and psychological changes may occur: Moods swings Most pregnant women, that is; both primigravida and multigravida experience the following signs and symptoms of imminent labour;

24. 1. Lightening This takes place about 2 -3 weeks before the onset of labour. This is when the lower uterine segment expands and allows the fetal head to sink lower in the pelvic inlet The fetus drops into the true pelvis and presenting part becomes engaged. After lightening, the woman can breathe easily.

25. Cont’d However, there is increased downward pressure of the presenting part which causes frequent backache as a result of relaxation of the sacro-iliac joint. Walking also becomes more difficult because the symphysis pubis is more mobile.

26. Cont’d Leg pains are experienced due to pressure on the nerves and increased venous stasis leading to edema in the lower extremities and increased vaginal secretions resulting from congestion of vaginal mucus membrane.

27. Cont’d Primigravidas are expected to experience lightening and engagement before labour begins where as the multigravida may not experience lightening until just before or during labour because in the multigravida the abdominal muscles are more lax resulting in a pendulous abdomen which delays engagement of the head.

28. Cont’d If lightening and engagement of the fetal head do not occur, there maybe a possibility of a small pelvic inlet or the presenting part may be too large.

29. 2. Frequency in micturation The congestion in the pelvis limits the capacity of the bladder so that it empties more often. There is poor sphincter control which gives rise to stress incontinence

30. 3. Braxton Hicks contractions These are irregular, intermittent contractions that occur throughout pregnancy. The contractions may be uncomfortable especially in the last few weeks of pregnancy resulting in false labour. They have been named after an obstetrician who described them.

31. 4. Taking up of the cervix The cervix is drawn up and gradually merges into the lower uterine segment. In the primigravida, there may be effacement of the cervix. 5. Gastro intestinal upsets Many women experience diarrhea, indigestion or nausea and vomiting few days before onset of labour.

32. 6. Burst of energy Some women have experienced a sudden burst of energy 24 to 48hours before labour. They engage in house cleaning and last preparations for the baby . 7.

33. STAGES OF LABOUR Labour is divides into three stages. First stage – from the onset of regular uterine contractions to full dilatation of the cervix. The stage lasts 8-12 hours in first labour and 3-8 hours in subsequent labour. Second stage- from full dilatation of the cervix to complete delivery of the baby. Lasts for 1-2 hours in primigravida and 30minutes to an hour in subsequent labour

34. Cont’d Third stage – from complete delivery of the baby to complete expulsion of the placenta, membranes and physiological control of bleeding.

35. To be continued