This document provides information about normal labor, including: - The definition of normal labor and its stages. Normal labor has 3 stages and may last 12 hours for a primigravida. - The signs and symptoms of each stage of labor. The first stage involves cervical dilation from 0-10cm. The second stage involves fetal expulsion. - The physiological changes that occur in the first stage, including uterine contraction, cervical effacement and dilation. - The factors that can influence the duration of normal labor, including primigravida/multipara status, pelvis size, and fetal size and position.

1. Normal Labor
Manju Yadav
Senior Hospital Nursing
Administrator
Koshi Hospital Biratnagar

2. Contents
• Definition
• Date of onset of labor
• Causes of onset of labor
• Pre-monitory sign of labor
• True pain and false pain
• Stage of labor
• Sign and symptoms of labor
• Duration of labor.
• Factors of normal labor
• Physiological changes in the first stage of labor
• Mechanical factors.

3. Labor
Definition
• Labor is the physiological process by which the fetus , placenta and
membrane are expelled through birth canal after 28 weeks of
pregnancy.
• Series of events that take place in the genital organ in an effort to
expel the viable product of conception out of the womb(uterus)
through the vagina in to the outer world is called labor.
• It may occur prior to 37 completed weeks which is known as preterm
labor.

4. Cont...
• Expulsion of pre viable fetus occurs through same process but in a
miniature from is called abortion.
• A parturient is a woman in labor and parturition is the process
of giving birth.

5. Normal labor
• Spontaneous in onset and at term.
• With vertex presentation.
• Without undue prolongation.( not less than 3 hrs and not more than
18 hrs.
• Natural termination with minimal aids.
• Without having any complication affecting the health of the woman
and /or the baby
• Mature fetus , of a single.
Normal labor is also known as eutocia.

6. Abnormal labor
Any deviation from the definition of normal labor is called abnormal
labor.
Abnormal labor is also known as dystocia.

7. Date of onset of labor
• It is very much unpredictable to foretell the exact date of onset of
labor . It is not only varies from person to person but even in different
pregnancies of the same individuals .
• According to Negele's formula can only give a rough guide.
• Based on the formula ,labor starts approximately on the expected
date in 4%.
• One week on the either side in 50%.
• 2 weeks earlier and 1 week later in 80 %.
• At 42 weeks in 10 %.
• At 43 weeks plus in 4%.

8. Causes of onset of labor
• The exact cause of the onset of labor is still uncertain, but it appears
to be multifactorial in origin, being combination of Hormonal and
Mechanical factors. There is evidence that something triggers the
fetal hypothalamus to produce releasing factors which stimulate the
anterior pituitary gland to produce adrenocorticotrophic hormone
(ACTH) which stimulate the fetal adrenal glands to secrete cortisol,
this causes changes in the relative level of placental hormones,
Estrogen and Progesterone. Oxytocin is also released. This gives
reason to some theories as to the causes of onset of labor.”

9. Cont…
1.Hormonal theory
• Oxytocin
• Progesterone deprivation theory
• Estrogen stimulation theory
• Prostaglandins
• Fetal endocrine control

10. Cont…
2. Mechanical theory
• Overdistension theory
• Increase contractibility
• Pressure of the presenting part
• Circulatory deprivation theory
3. Neurological factor

11. Cont…
• Hormonal theories:
• Oxytocin: A hormone produced from the posterior pituitary gland
which the uterine muscle is very sensitive to. It is released in high
dose at the end of pregnancy leading to contraction of the uterine
muscle. Maybe as a result in progesterone: Estrogen ratio, also the
reduction in the level of oxytocin's in the blood stream makes the
muscles more sensitive to oxytocin. Estrogen facilitates the release of
oxytocin. Oxytocin stimulates the release of prostaglandins from the
myometrium of the hormone.

12. Cont…
• Progesterone deprivation theory: During pregnancy, progesterone is
secreted in high level which has a sedative
• effect on the uterine muscle making it remain relaxed. As pregnancy
advances the level of progesterone get reduced so the uterus
becomes more active so that a diminished amount leads to onset of
labor. Progesterone has opposite effect to that of estrogen, making
the myometrium less sensitive to stimuli.

13. Cont…
• Estrogen stimulation Theory: there is an opinion that the rising level of
estrogen during the last few weeks of pregnancy results in the formation of
oxytocic receptors in the uterine muscle cells. This makes the muscle
respond more easily to stimuli or to oxytocin.
• Estrogen The probable mode of action are:
• Increase the release of oxytocin from maternal pituitary gland .
• Promote the synthesis of receptors for oxytocin in the myometrium.
• Increased prostaglandin synthesis.
• Stimulate the synthesis of myometrial contractile protein actomyosin
through activation of adenosine triphosphatases.
• Increase the excitability of the myometrial cell membrane.

14. Cont…
• Prostaglandins: Is found in high level in the amniotic fluid and blood
stream during labor. They initiate uterine contraction. The rising level
of estrogen increases oxytocin receptors in the myometrium.
Oxytocin stimulates the release of prostaglandin from the decidua's
and membranes. The role played by this hormone is yet to be fully
investigated but it is known to have oxytocic effect on uterine
muscles.

15. Cont…
• Fetal Endocrine Control: there is interaction between the fetal
adrenal gland and the uterus. At term the fetal adrenal gland secret
corticoid steroid which is believed to trigger the release of
prostaglandin in the maternal decidua, a mechanism leading to labor.
By stimulate the precool to prostaglandin synthesized in the decidua
at term.

16. Cont…
• Mechanical Theories:
• Overdistension/Uterine stretch theory: During pregnancy the uterus is in
pace with its content, but when it stretches to it’s maximum it starts to
contract to expel it’s content . This evidence can be seen in multiple
pregnancy and Polyhydramnios.
• Increase contractibility: As the end of pregnancy approaches the normal
Braxton Hicks contractions becomes exaggerated as the uterus becomes
more sensitive to stimuli.

17. Cont…
• Pressure of the Presenting part: On the cervical nerve endings is
thought to stimulation nerve plexus (known as cervical ganglion)
which result in secretion of oxytocin by the Posterior Pituitary Gland
(PTG). This gives the reason why labor is very fast with engaged head.
• Circulatory Deprivation theory: Towards end of pregnancy the
placental functions become inefficient thereby leading to reduction in
circulatory nutrition and blood supply to the fetus.

18. Cont…
3. Neurological factor
• Both alpha and beta adrenergic receptors are present in the
myometrium.
• Estrogen causing the alpha receptors and progesterone the beta
receptors to function predominately.
• The contractile response is initiated through the alpha receptors of
the post ganglionic nerve fibers and around the cervix and the lower
part of the uterus.

19. Premonitory sign of labor
• The premonitory stage may begin two or three weeks before the
onset of true labor in primigravida and few days before in
multigravida. It is also known as pre-labor. The features are
inconsistent and may consist of the following.
1. Lightening
2. Cervical changes
3. Appearance of false pain
4. Taking up the cervix
5. Sudden burst of maternal energy/activity.
6. Slight decrease in maternal weight.

20. Cont…
1. Lightening
• This is the sinking of presenting part into the true pelvis, which takes
place about 2-3 weeks before onset of labor in primigravida and
during the onset of labor in multigravida.
• It is active pulling of the lower pole of the uterus around the
presenting part.
• The women experience a sense of relief form the mechanical
cardiopulmonary embarrassment. Breathing is easier, the heart and
stomach can function better and relief experience by the women is
described as “lightening”.

21. Cont…
Cervical changes
Variable days prior to the onset of labor, the cervix becomes ripe. A
ripe cervix is soft less than 1.3 cm in length, admits a finger easily and
is dilatable .
Ripe cervix
it feels soft to the touch. When firm, your cervix will feel like an unripe
piece of fruit. When it gets soft, it feels more like ripe fruit. You might
also hear that a firm cervix feels like the tip of your nose and a soft
cervix feels like your lips.

22. Cont…
• Appearance of false pain
There are erectile and irregular pain, causing the uterus to contract
and relax, where as in labor the uterus becomes contract and retracts.
• Taking up of the cervix
As effacement takes place, the cervix then shortens, or effaces, pulling
up into the uterus and becoming part of the lower uterine wall.
Effacement may be measured in percentages, from zero percent (not
effaced at all) to 100 percent, which indicates a paper-thin cervix.
Effacement is accompanied by cervical dilation.

23. Cont…

24. True pain and false pain
• True pain
The features of true labor pain are
1. Painful uterine contraction.
2. Appearance of show
3. Progressive effacement and dilation of the cervix.
4. Formation of “bag of water.”

25. Cont…
• Painful uterine contraction
• throughout pregnancy , painless Braxton hicks contraction with
simultaneous hardening of the uterus occur. These contraction changes
their character , become more powerful , intermittent and are associated
with pain. The pain are more often felt in front of the abdomen or radiating
towards the thighs.
• Appearance of show
With the onset of labor , there is profuse cervical secretion. Simultaneously,
there is slight oozing of blood from rupture of capillary vessels of the cervix
and from the raw decidual surface caused by separation of the membrane
due to splitting off the lower uterine segment. Expulsion of cervical mucus
plug, mixed with blood is called show.

26. Cont…
• Dilation of internal os
With the onset of labor pain, the cervical canal begins to dilate more in
the upper part than in the lower , the former being accompanied by
corresponding stretching of the lower uterine segment .
• Formation of bag of water
With the dilation of the cervical canal , the lower pole of the fetal
membrane becomes unsupported and tend to bulge in to the cervical
canal.

27. 1. Cont…
• False labor pain
It usually appears prior to the onset of true labor pain , by one or two
weeks in primigravida and by a few days in multipara .it is found more
in primigravida than multigravida women. The women feels pain and
discomfort in the abdomen and these are mistaken for labor pain. False
pain has following features.
1. dull in nature and usually confined to the lower abdomen and
groin.
2. continuous and unrelated with hardening of the uterus.
3. Without any effect on dilation of the cervix.

28. Cont…
SN Features True labor False labor
1 Painful uterine contraction irregular regular
2 Interval between pain Gradually shortens Remains long
3 intensity increase same
4 Site of pain Back and abdomen Chiefly lower abdomen
5 Cervical dilation and effacement present absent
6 Bulging of fore water present absent
7 sedation Pain not stopped Usually relieved
8 enema Not relieved relieved
9 General condition by walking intensified Not intensified
10 show Usually present absent

29. Stages of labor
Conventionally ,events of labor are divided into three stages. But nowadays ,
it can be divided into 4 stage.
1. First stage
• Latent phase (early )
• Active phase
• Transitional phase
2. Second stage of labor.
• The Propulsive phase
• The expulsive phase
3 . Third stage of labor
4. Fourth stage of lobor.

30. Cont…
1. First stage of labor
it starts from the onset of true labor pain and ends with full dilation of
the cervix. It is also known as the “cervical stage “of the labor. Its
average duration of labor is 11-12 hours in primigravida and 6-7 hours
in multipara . It has three sub phases.
• Latent phase (early)
contractions are usually every 5-20 minutes , lasting 20-40 sec. and of
mild intensity and cervix dilates from 0-4 cm. the contraction progress
to about every 5 minutes and establish a regular pattern.

31. Cont…
• Active phase
contraction are usually every 2-3 minutes; lasting 30-50 sec and of
mild to moderate intensity. Cervix dilates from4-7 cm. after reaching
the active phase, dilation average is 1.2 cm. per hour in nulli para and
1.5 cm per hour in the multipara.
• Transitional phase
Contraction comes in every 2-3 minutes, lasting 50-60 seconds and to
moderate to strong intensity. Some contraction may last up to 90 sec.
the cervix dilates from 8-10 cm.

32. Cont…
2. Second stage of labor - it starts from the full dilation of the cervix and
ends with expulsion of the fetus from the birth canal . It has got two phase.
• Propulsive phase -
Starts from full dilation up to the descent of the presenting part to the
pelvic floor.
• Expulsive phase
Is distinguished by maternal bearing down effects and ends with delivery of
the baby
The average duration is 1-2 hrs in primigravida and 5-30 minutes in
multipara.

33. Cont…
3 . Third stage of labor – it begins after expulsion of the fetus and ends
with expulsion of the placenta and membranes after birth. This stage is
also concerned with control of bleeding . Its average duration is about
15-30 minutes in both primigravida and multigravida. The duration is
however reduced to 5 minutes in active management.
4. Fourth stage of labor- 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 woman and the behavior of the uterus
are to be carefully watched.

34. Sign and symptoms of labor
Sign and symptoms of First stage labor
• Baby drop
• Cramps and increased back pain.
• Loss of mucus plug and vaginal discharge change.
• Painful uterine contraction
• Progressive dilation of the cervix from 0 cm to 10 cm.
• Bulging of membrane during contraction.
• Rupture of membrane
• Stomach becoming hard and then soft again.

35. Cont…
Sing and symptoms of second stage of labor
• Strong regular and expulsive uterine contraction.
• Bulging of perineum and membrane.
• Vulva and anus gaping
• Complete taking up of cervix
• Crowning of fetal head
• Bearing down by women
• Rupture of membrane
• Delivery of head and shoulder then whole body.

36. Cont…

37. Duration of labor or normal course of labor
There are wide variations in the duration of labor depending on
whether the woman is a primigravida or multipara and on the time that
has elapsed since the birth of her last child . The type of pelvis, size
and presentation of the fetus and strength and frequency of the
uterine contractions, all influence the length of labor.
The greater part of labor is taken up with the first stage. Seldom in
the second stage less than half an hour in primigravida and the
multiparous woman may have a second stage of 15 min or less. The
duration of the third stage is usually between 5 and 20 minutes.

38. Cont…
First stage Second stage Third stage total
primigravida 11 hours ¾ hours ¼ hours 12 hours
multigravida 6 .5 hours ¼ hours ¼ hours 7 hours

39. Factors of normal labor
The factors or process which may affect the labor process is known as
factors of normal labor. There are: 4 p
1. power(primary and secondary force to expel fetus).
2. Passage : a. soft tissue passage: change in uterus , cervix, vagina ,
pelvic floor.
b. bony passage: pelvic outlet
3. passenger: fetus ,placenta, membrane, liquor amnii,cord.
4. Psychological response of mother.

40. Physiological changes in first stage of labor
Knowledge of the physiological changes during labor is important to
interpret intelligently and to recognize any deviation from the normal
course. During first stage of labor , following physiological changes are
occurs
1.Contraction and retraction of uterine muscles.
• Uterine contraction
• Fundal dominance
• Polarity
• retraction

41. Cont…
2. Formation of upper and lower uterine segment
3. Development of the retraction ring
4. Taking up of the cervix( cervical effacement)
5 . Cervical dilation
6. Presence of show

42. Cont…
1. Contraction and retraction of uterine muscles
• Uterine contraction are involuntary , they are controlled by the
nervous system and by endocrine influence. They usually recur with
rhythmic regularity, and the intervals between them gradually
diminish from 15 minutes, more or less at the beginning of the first
stage, to two or three minutes at the end of the first stage.
• fundal dominance: each contractions starts in the fundal region
near one of the cornua and spreads downwards and across being
stronger and persisting longer in the upper region. The fundus and
mid-zone remain hard throughout the period of contraction.

43. Cont…

44. Cont…
• Polarity :polarity is term used to describe the neuromuscular harmony
that prevails between the two poles of the uterus throughout labor. During
each uterine these two poles act harmoniously . The upper pole contract
strongly and retract to expel the fetus, the lower pole contract slightly and
dilate to allow expulsion of fetus. If polarity is disorganized , the labor is not
progressed.
• Retraction : retraction is special function of uterine muscles whereby the
contraction does not pass off entirely ; the muscle fibers retaining some of
the contraction instead of becoming completely relaxed. Retraction assist
in the progressive expulsion of the fetus ; the upper segment of the uterus
becomes shorter and thicker and its cavity diminished.

45. Cont…

46. Cont…

47. Cont…
2 . Formation of upper and lower uterine segment:
At the end of pregnancy ,the uterus is divided functionally into two
segments ;upper and lower. The upper segment is the thick , muscular
contractile part, and the lower segment is the thinner distensible
area 7.5 cm to 10 cm in length, which has developed from the isthmus
of the uterus . When the labor begins ,the retracted longitudinal fibers
in the upper segment pull on the lower segment , causing it to stretch ,
this is aided by the force applied by the descend of presenting part.

48. Cont…
3. Development of the retraction ring
The ridge which form at the lower border of the thick upper segment where
it meets the thinner lower segment is known as the retraction or bandl’s
ring. It is present in every labor and is perfectly normal until it is not marked
enough to be visible above the symphysis pubis. In normal labor it is not
visible because the fetus is gradually being expelled through the dilating
cervix . But in obstructed labor, where the fetus can not descend to pass
through the cervix , the lower , segment must stretch to accommodate it,
because the fetus is being pushed out of the shortened upper segment . In
such cases , retraction ring would be visible transversely or slightly obliquely
across the abdomen, above the symphysis pubis. It may cause rupture of
uterus . Retraction ring is termed in case of invisible and bandl’s ring when it
becomes visible.

49. Cont…

50. Cont…
4. Taking up of the cervix:
It is a process of thinning and shortening out of the cervix . The cervix is
gradually effaced which is like a funnel shaped . The muscle fibers
surrounding the internal os are drawn upward by the retracted upper
segment. The cervix is shortened and gradually effaced , taking up of
the cervix denotes complete dilation of the cervix which signifies the
end of first stage.

51. Cont…

52. Cont…
5. Cervical dilation:
The external os begins to enlarge from a circular opening . It is aided by
upward traction, exerted by the retracted muscle fibers in the upper
segment exerts pull on the margin of the weakened area- the cervix and
makes the os enlarge. The well flexed head will , when closely applied to
the cervix , aid dilation.
In the primigravida woman the external os may be closed at the beginning
of labor or it may admit the tip of one finger and does not dilate the until
the cervix has been taken up, but the internal os dilate during the process
of taking up of the cervix .

53. Cont…
In the multiparous woman, the external os usually admits one finger
prior to the onset of labor and dilation of the external and internal os
proceed simultaneously with taking up of the cervix.
6.Presence of show: This is the blood stained mucoid discharge seen a
few hours before or within a few hours after labor has started. The
mucus is the thick, tenacious substance which formed the cervical plug
–operculum-during pregnancy. The blood comes from the ruptured
capillaries of the decidua vera where the chorion become detached
and from the dilating cervix. `

54. Mechanical factors
1.Formation of bag of water
2. General fluid pressure
3. Fetal axis pressure
4. Rupture of the membrane

55. Cont…
1 . Formation of the bag of water:
The membrane (amnion and chorion) are attached loosely to the decidua , a
lining the uterine cavity except over the internal os. In vertex presentation,
the girdle of the head being spherical, may well felt with the wall of the
lower uterine segment. Thus the amniotic cavity is divided into two
compartments. The part above the girdle of contact contain the fetus with
bulk of the liquor called hind water and the one below it containing small
amount of liquor called fore water.
with the onset labor, the membrane attached to the lower uterine segment
are detached and with the rise of intrauterine pressure during contraction
there is herniation of the membrane through the cervical canal.

56. `cont…
Because of ballvalve like action by the well flexed head, the force
exerted by uterine contraction can not be transmitted squarely and
hence the bag of membranes bulges out and remains intact until
the cervix is almost fully dilated.

57. Cont…

58. Cont…
2.General fluid pressure:
While the membrane remains intact , the pressure of the uterine
contractions is exerted on the fluid , and as fluid is not compressible
the pressure is equalized throughout the uterus and is known as
general fluid pressure.
When the membrane rupture and a quality of fluid escape, the
compression is lied over placenta so oxygen supply to the fetus is
diminished and there is risk of fetal hypoxia during uterine
contraction.

59. Cont…

60. Cont…
3. Fetal axis pressure:
When the fetus lies longitudinally In flexed attitude there is a tendency
of straightening out of the fetal axis due to contraction of circular
muscles of the body of uterus . This allows the fundal contraction to
transmit through the podalic pole into the fetal axis and hence allows
mechanical stretching of the lower segment and opening up of the
cervical canal. However , fetal axis pressure cannot operate in
presence of excess liquor or in cases of transverse lie where smooth
dilation occurs.

61. Cont…

62. Cont…
4. Rupture of the membrane :
The amniotic sac should remain intact until the cervix is fully dilated,
but this by no means always happens the membrane may rupture
days before labor begins or during the first or second stage and in
same instance not until the head is being born. Rarely , spontaneous
rupture may not take place at all, allowing the baby to be “ born in a
caul”. Towards the end of the first stage the bag of membrane
receives very little support , because of the extensive dilation of the
cervix. It is also subjected to the increased force of the strong uterine
contraction. If there is badly fitting presenting part, the fore water
are not cut off effectively and the membranes rupture early , but
some cases this happens for no apparent reason.

63. Cont…