1. The physiology of birth, puerperium and lactation

2. Objectives Describe physiology of initiation of labor
Define normal and abnormal labor
Describe normal puerperium
11/21/2018

3. Parturition Normal Pregnancy Parturition Uterine quiescence
Fetus
Mother
Placenta
Membranes
Normal Pregnancy
Uterine quiescence
Immature fetus
Closed cervix
Parturition
Coordinated uterine activity
Maturation of the fetus
Maternal lactation
Progressive cervical dilation
11/21/2018

4. Uterine Activity During Pregnancy
Inhibitors
Progesterone
Prostacycline
Relaxin
Nitric Oxide
Parathyroid hormone-related peptide
CRH
HPL
Quiescence
Uterotrophins
Estrogen
Progesterone
Prostaglandins
CRH
Activation
Uterotonins
Prostaglandins
Oxytocin
Stimulation
Involution
Oxytocin
Thrombin
11/21/2018

5. Initiation of labor Oxytocin Peptide hormone
Hypothalamus-posterior pituitary
Fetal production
Maternal serum increase in second stage of labor
Oxytocin receptors
Fundal location
x during pregnancy
Actions
Stimulate uterine contractions
Stimulate PG production from amnion/decidua
11/21/2018

6. Initiation of Labor Fetus Sheep Humans Fetal ACTH and cortisol
Placental 17 α hydroxylase
 Estradiol
 Progesterone
Placental production of oxytocin, PGF2 α
Humans
Fetal increased DHEA
Placental conversion to estradiol
Increased decidual PGF2 and gap junctions
Increased oxytocin and PG receptors
Decreased progesterone receptors
11/21/2018

7. The physiology of uterine activity
the miometrium is composed by muscular tissue
the muscular content decreases towards the cervix so that muscle forms no more than 10% of cervical tissue

9. Biochemistry of muscle activity
the contraction is based on the interaction of myosin and actin which is effected by enzymatic phosphorilation of the light chain of myosin
the phosphorilation in catalized by the enzyme kinase which is activated by Calcium.
Calcium binds to calmodulin wich activates miosin light chain kinase

10. Uterine contractions cAMP + Oxytocin + Prostaglandin Oxytocin receptor
Extracellular
Calcium channel
Intracellular
Phospholipase C
cAMP
Ca+
MLCK
Ca store
+ Oxytocin
+ Prostaglandin
Oxytocin binds receptor and activates phospholipase c. PHC increase intracellular Ca by release of intracellular calcium and promote influx of calcium. Ca binds myosin light chain kinase
Uterine contractions
11/21/2018

11. Effect of calcium
Agents that act on myometrial muscle cells to cause an increase in Calcium –promote contraction
Conditions that cause a decrease in Calcium favor relaxation
Calcium antagonist as nifedipine are tocolytics
Calcium administration may help uterine contraction

12. Muscle fibre contraction
In the presence of estrogen, an impulse alters the electric potential of the cell membrane and permits the entry into the contractile fibril of sodium and calcium ions, which start the energy-releasing cycle
This pulls the actin fibrils into the spaces between the myosin fibrils

13. Caracteristics of myometrial contractions
the uterus functions as a single muscular organ
uterine muscles are never completely relaxed (between contractions there is a restingtone of 6-12 mmHG)
the frequency of contraction is expressed as the number per unit of time
The Montevideo Units are the product of intensity and frequency over a 10 minute period and they give a measurement of uterine activity

14. Montevideo
Research of uterine contraction

15. True labor Contractions at regular intervals
Intervals gradually shortens
Intensity gradually increases
Minimum 2 contractions in 10 min
No response to antispastic drugs

16. cardiotocograph to measure the uterine acivity internal/external

17. The “pacemaker” is located at the junction of the Fallopian tube and uterus, on each side.
In each woman, one of them is dominant , and it is from there that all contractile waves originate.

19. in the second stage of labor, voluntary contractions of the diaphragm and abdominal muscles, added to the uterine contraction, propels the baby downwards, through the dilated cervix and vagina.
uterine activity continues unaltered after expulsion of the fetus and leads to the expulsion of placenta.

20. Normal labor and delivery
The mechanism by which human parturion is initiated spontaneously, either at term or preterm, is NOT KNOWN
it is not possible to determine when labor will begin

21. Uterine phases of parturition
Phase 0 – the prelude of parturition
Phase 1 – the uterus is getting ready for labor, when functional changes in myometrium and cervix are required (last days of pregnancy)
Phase 2 – the period of active labor : the uterine contractions that bring about progressive cervical dilatation, fetal descent and delivery (the 3 stages of labor)
Phase 3 – parturient recovery takes place

22. The phases of parturition should not be confused with the clinical stages of labor
UTERINE QUIESCENCE
95% of pregnancies
Can be some uterine contractions, low intensity, brief duration
There is no cervical dilation
Near the term, Braxton=Hicks contraction/ false labor especially at multipara
The uterine smooth muscle does not respond to stimuli

23. PHASE 1 PREPARATION FOR LABOR
Myometrial tranquility is suspended= uterine awakening or activation
Cervical modifications during phase 1= invasion by inflammatory cells, like inflammation
Softening of the cervix= ripening
Factors: prostaglandins E2, F2 α, cytokines
Collagen breakdown
We use prostaglandin gel to ripe the cervix
Cervical ripening is an essential step of labor
Cervical dystocia !

24. PHASE 1 PREPARATION FOR LABOR MYOMETRIAL CHANGES
Alteration in expression of key proteins that control myometrial contractility
Contraction associated proteins= CAPs
Striking increase in myometrial oxytocin receptors and gap junctions

25. Uterine contraction are painful=unique phenomenon
Cause of the pain is not known
Hypoxia of contracted myometrium ( as in angina pectoris)
Stretching of the cervix during dilatation( highly sensitive area)
Stretching of peritoneum over the fundus
Compression of the nerve ganglia in the cervix and lower uterine segment/ paracervical infiltration with anestethic produces relief of pain
Mechanical stretching of the cervix increase uterine contraction( Fergusson reflex)

26. CERVIX 2 MAJOR CHANGES Effacement and dilatation
Effacement shortening of the cervical canal from a length of 4 cm to a circular orifice with paper-thin edges

27. CERVICAL DILATATION 2 phases latent phase and active phase
Latent phase the durate is variable
Active phase acceleration
maximum slope
deceleration

28. FRIEDMAN

29. Labor stages First stage – onset of labor to complete dilatation
Latent phase – onset to rapid cervical change
Active phase – rapid cervical change to complete dilatation
Second stage
Third stage
Fourth Stage
Nulliparous
Multiparous
Mean
95th
% tile
%tile
Latent phase hr
17-21 hr hr
12-14 hr
Active phase
1.5cm/hr
1.2cm/hr
11/21/2018

30. Labor stages First stage – onset of labor to complete dilatation
Second stage – complete dilatation to delivery of neonate
Third stage
Fourth Stage
Nulliparous
Multiparous
Mean
95th
% tile
%tile
No epidural
53-57
min
17-19
57-61
Epidural
79 min
185 min
45min
131min
11/21/2018

31. Labor stages First stage – onset of labor to complete dilatation
Second stage
Third stage
Delivery of the placenta
Mean – 6 minute
97th% < 30 minutes
Prolonged
EBL >500
Need for D&C
Drop in HCT by 10%
11/21/2018

32. Maternal factors Uterotropin= agents that prepares the uterus
Uterotonin=uterine smooth muscle contractant
Oxytocin- number of receptor increases in labor
Prostaglandins
Endothelin 1
Miometrial cell - Calcium

33. Fetal factors
In late pregnancy the fetal pituitary produces ACTH and oxytocin
These 2 hormones may be involved in the coordinated rhytmic uterine contraction which caractherizes labor

34. If induction of labor fails Postdate pregnancy
Chronic fetal distress
Placenta fails
Can lead to fetal death
After 41/42 weeks induction of labor by oxytocin/ prostaglandin gel

35. The physiology of the puerperium
Puerperium is defined as the period after birth
During this time, the reproductive tract returns anatomically to a normal nonpregnant state, and in most women who are not breast feeding, ovulation is reestablished

36. Classification Early puerperium : 4 hours after childbirth
The veritable puerperium : 10 days after childbirth
Late puerperium: 30 days after childbirth

37. Early puerperium= 4 hours
The woman rests in the delivery room
Pulse and blood pressuse must be observed
The form and consistance of the uterus must be checked out
The Pinard’s globus is firm and globulous due to contraction and retraction of the uterus
Blood loss is about 250 ml

38. The veritable puerperium > 4 hours – 10 days
Specific phenomena - involution of the uterus
- the lochia
- lactation
Modifications of the organs and systems

39. Involution of the uterus
immediatly after placental expulsion, the fundus of the contracted uterus is slightly below the umbilicus
the process by which the uterus returns to nonpregnant state is known as “involution”
the uterus reduces by about 1-1,5 cm / day
fundal height is measured each day
failure of involution suggests retained placental tissue

41. The lochia
Early in puerperium, sloughing of decidual tissue results in a vaginal discharge of variable quantity, this is termed LOCHIA
It is made by erythrocytes, shreds of decidua, epithelial cells and bacteria.
Foul-smelling is suggestive of infection=endometritis
The quantity of the lochia varies from day to day and the total quantity in 1000 ml.

42. T
the obstetrician

43. “lochia rubra” - first few days “lochia serosa” - after 3-4 days “lochia alba”- after 10 days

44. Lactation
during pregnancy the breasts develop due to the increasing of estrogen and progesterone
estrogen leads to an increse both in size and number of the duct system
progesterone appears to increse the number of alveolar cells
during lactation, there is a decrease in the amount of adipose tissue relative to glandular tissue, and the size and the weight of the breasts increases

47. during pregnancy the breasts secrets colostrum
it is a yellowish fluid, containing a much greater quantity of proteins than normal milk, plus desquamated endothelial cells
it’s gamma-globulin content may be a prevision for the supply of antibodies

48. following child birth and placental expulsion, the estrogen levels fall within 3 days, permitting prolactin to act , and to initiate lactation.
neurohypophysis releases oxytocin by reflex suckling
the oxytocin causes contraction of the myoepithelial cells and ejection of the milk

49. for the maintenance of lactation suckling is essential and it is also necessary to have normal levels of : ACTH
- growth hormone
- thyroid hormone
- insulin
the major components of milk are proteins, lactose, water and fat
all vitamins, except vitamine K are found in the human milk but in variable amounts.

50. Breastfeeding is GOOD
BENEFITS FOR MOTHER
BENEFIT FOR CHILD

51. Changes in the cervix and vagina
immediatly after the third stage of labor, the cervix and the lower uterine segment are thin, collapsed, flabby structures
the outer margins of the cervix is usually lacerated, especially laterally
the cervical opening contracts slowly for a few days immediately after labor
by the end of the first week it has narrowed to a one-finger diameter
as the cervical opening narrows, the cervix thicknes and the canal is reformed

52. Vagina and vaginal outlet
early in puerperium, the vagina form a capacious, smooth-walled passage that gradually diminishes in size but rarely returns to nulliparous dimensions
the hymen is represented by several small tags of tissue, which during cicatrization are converted into myrtiform caruncles characteristic to parous women

55. Changes in urinary tract
in the first few hours after delivery micturition may be difficult, partially because of reflex suppresion of detrusor activity and sphincter spasm
during the first 1 or 2 days a marked diuresis occurs, because of a fall in progesterone content of the blood and the alteration of cell metabolism to the non-pregnant state

56. Blood
marked leukocytosis occurs during and after labor (sometimes reaching per ml)
there is also a relative lymphopenia and an absolute eosinopenia
normally, during the first few postpartum days, hemoglobin, hematocrit and erythrocyte counts fluctuate moderately
by one week after delivery, the blood volume has returned to almost its nonpregnant level

57. Bowel function
constipation has become much less of a problem in the puerperium
routine prescription of a stool softener is a common practice

58. Late puerperium
Following vaginal delivery the hospitalization is warranted for 72 hours
Before discharge, the woman should receive instruction concerning the anticipated normal physiological changes of the puerperium, including changes in lochia patterns, weight loss due to diuresis and whan to expect milk let down

59. Restoration of ovulation and menstruation
the more frequently the child suckles, the higher is the plasma prolactin level and the longer ovulation is delayed
however, some lacting women, especially those who only partially breast-feed, ovulation may occur, and subsequently pregnancy without any menstrual period
ovulation is unusual among lactation women for about 20 weeks

60. Menstruation may start earlier:
- 10% of breast feeding women menstruate by the 10-th week after birth
- 40% by 20 weeks
- 50% by 30 weeks

61. Thank you !