1. Obstetrics & Gynecology Hospital of Fudan University Xu Huan
Preterm Labor
Obstetrics & Gynecology Hospital of Fudan University
Xu Huan

4. Introdution Labor and delivery between 28 – 36+6 weeks 5%-10%
be the leading cause of perinatal morbidity and mortality
Survival rates have increased and morbidity has decreased because of technologic advances

5. Definition (WHO) Incidence (6%-10%)
Preterm labor is the presence of contractions of sufficient strength and frequency to effect progressive effacement and dilatation of the cervix between 20 and 37 weeks’ gestation
Definition (WHO)
Spontaneous : 40-50%
PROM : 25-40%
Obstetrically indicated : 20-25%
Incidence
(6%-10%) 5

6. Survival by gestational age among live-born resuscitated infants
In: Creasy, Resnik . Maternal – Fetal Medicine, 2009 6

7. Pathophysiology 7

8. Ascending intrauterine infections stage I changing flora vagina/cervix, II Microorganism alocated between the amnion and chorion, III intra amniotic infection, IV fetal invation
The preterm parturition syndrome. Multiple pathologic processes can lead to activation of the common pathway of parturition.
In: Creasy, Resnik . Maternal – Fetal Medicine, 2009 8

9. Infections associated with preterm delivery
Genital * Bacterial vaginosis (BV)
* Group B streptococcus
* Chlamydia
* Mycoplasmas
Intra-uterine * Ascending (from genital tract)
* Transplacental (blood-borne)
* Transfallopian (intraperitoneal)
* Iatrogenic (invasive procedures)
Extra-uterine * Pyelonephritis
* Malaria
* Typhoid fever
* Pneumonia
* Listeria
* Asymptomatic bacteriuria
In:Jane Norman.Preterm labor 2005 9

10. Stretch Inflammation Abruption Stress Thrombin ↑ CRH ↑ Estrogen
Integrins
↑IL-1β
↑TNF-α
↑COX2
↓ PGDH
↓ PR-B
↑ MMPs
↑ IL-6 and 8
PTL or PPROM
Principal biomechanical mechanisms responsible for chain pathways of preterm parturition COX2=cyclooxygenase2, PGDH=prostaglandin dehydrogenase PR-B=Progesteron receptorB.CRH=corticotropin releasing hormon MMPs=matrix metallo proteinase
In: Creasy, Resnik . Maternal – Fetal Medicine, 2009 10

11. Risk Factors(1) Previous preterm delivery Low socioeconomic status
Maternal age <18 years or >40 years
Preterm premature rupture of the membranes
Multiple gestation
Maternal history of one or more spontaneous
second-trimester abortions
Maternal complications (medical or obstetric)
Lack of prenatal care

12. Risk Factors(2) Uterine causes Abnormal placentation
Myomata (particularly submucosal or subplacental)
Uterine septum
Bicornuate uterus
Cervical incompetence
Abnormal placentation

13. Risk Factors(3) Infectious causes Fetal causes Chorioamnionitis
Bacterial vaginosis
Asymptomatic bacteriuria
Acute pyelonephritis
Cervical/vaginal colonization
Fetal causes
Intrauterine fetal death
Intrauterine growth retardation
Congenital anomalies

14. Diagnosis
Documented uterine contractions(4 per 20 minutes or 8 per 60 minutes)
Documented cervical change (cervical effacement of 80% or cervical dilatation of 2cm or more)

15. Forecast uterine activity monitoring.
Ultrasound Examination of Cervical length
Fetal Fibronectin

16. Major Risks of Preterm Delivery
PRETERM LABOR  Most mortality and morbidity is experienced by babies born before 34 weeks
Major Risks of Preterm Delivery
Death
Respiratory distress syndrome
Necrotising enterocolitis
Jaundice
Hypothermia
Hypoglycaemia
Infection
Retinopathy of prematurity
Goldenberg, Obstetrics & Gynaecology 16

17. Treatment(1)
An initial assessment: ascertain cervical length and dilatation and the station and nature of the presenting part
Bed Rest : be placed in the lateral decubitus position

18. Although bed rest is often prescribed for women at high risk for preterm labor and delivery, there are no conclusive studies documenting its benefit.
A recent meta-analysis found no benefit to bed rest in the prevention of preterm labor or delivery.

19. Treatment(2) Tocolytic therapy
Magnesium sulfate (Intracellular calcium antagonism) has become the drug of choice for initiating tocolytic therapy.
Terbutaline (Bricanyl) Beta2-adrenergic receptor agonist sympathomimetic; decreases free intracellular calcium ions
Nifedipine(Procardia) Calcium channel blocker

20. Tocolytic Therapy
Prostaglandin synthetase inhibitors: indomethacin, administered both orally and rectally
Ritodrine (Yutopar) Same as terbutaline
Nifedipine Indomethacin (Indocin) Prostaglandin inhibitor

21. Tocolytic therapy may offer some short-term benefit in the management of preterm labor.
A delay in delivery can be used to administer corticosteroids to enhance pulmonary maturity and reduce the severity of fetal respiratory distress syndrome,

22. also be used to facilitate transfer of the patient to a tertiary care center
No study has convincingly demonstrated an improvement in survival, long-term perinatal morbidity or mortality, or neonatal outcome with the use of tocolytic therapy alone.

23. Potential Complications Associated With the Use of Tocolytic Agents :
Magnesium sulfate
• Pulmonary edema
• Profound hypotension*
• Profound muscular paralysis*
• Maternal tetany*
• Cardiac arrest*
• Respiratory depression*

24. Beta-adrenergic agents
• Hypokalemia
• Hyperglycemia
• Hypotension
• Pulmonary edema
• Arrhythmias
• Cardiac insufficiency
• Myocardial ischemia
• Maternal death

25. Indomethacin (Indocin)
• Renal failure
• Hepatitis
• Gastrointestinal bleeding
Nifedipine (Procardia)
• Transient hypotension

26. Treatment(3) Corticosteroid Therapy Dexamethasone and betamethasone
for fetal maturation reduces mortality, respiratory distress syndrome and intraventricular hemorrhage in infants between 28 and 34 weeks of gestation.
benefits start at 24 hours and last up to seven days after treatment
The potential benefits or risks of repeated administration of corticosteroids after seven days are unknown.

27. Treatment(4) Antibiotic Therapy
women who received antibiotics sustained pregnancy twice as long as those who did not receive antibiotics
had a lower incidence of clinical amnionitis.
poor fetal outcome (death, respiratory distress, sepsis, intraventricular hemorrhage or necrotizing colitis) occurred less frequently in women receiving antibiotics

28. Treatment(5) Labor and deliverey
With modern neonatal care, the lower limit of potential viability is 24 weeks or 500g, although these limits vary with the expertise of the neonatal intensive care unit.
Continuous fetal heart monitoring and prompt attention to abnormal fetal heart rate patterna are extremely important.
With a vertex presentation, vaginal delivery is preferred.
Use of outlet forceps and an episiotomy to shorten the second stage are advocated.
Cesarean section for delivery of the very low birth weight baby
For the breech fetus estimated at less than 1500g, neonatal outcome is improved by cesarean section

29. Premature of membrane

30. Definition
Premature rupture of the membranes (PROM) is defined as amniorrhexis (spontaneous rupture of membranes) prior to the onset of labor at any stage of gestation

31. Incidence PROM occurs in about 10-15% of all delivery
PROM is associated with 10% of term pregnancy

32. Cause of PROM(1)
The cause of PROM is not clearly understood, perhaps associated with the follow factors:
Trauma
Sexual intercourse (particularly in the late gestational weeks)
lax of internal os of uterine

33. Cause of PROM(2)
Vaginal infection due to bacteria, virus, TOXO, CMV, HPV, HSV, et al STDs sexually transmitted diseases play an important role in the cause of PROM, because such infections are more commonly found in women with PROM than in those without PROM
Increased of intra-uterine pressure (such as multiple pregnancy and hydraminios)
Abnormalities in presentation and position

34. Cause of PROM(3)
Smoking the risk of PROM is at lease doubled in women who smoke during pregnancy
Other factors for PROM include the follow
Prior PROM
A short cervical length
Prior preterm delivery
Bleeding in early pregnancy

35. Manifestation and Diagnosis
Fluid passing through the vagina suddenly, and then small amounts of fluid flow through the vagina intermitently, particularly when the increased of abdorminal pressure (cough, sneeze, et al)
Intermittent urinary leakage is common during pregnancy, especially near term
Increased vaginal secretions in pregnancy
Perineal moisture
Increased cervical discharge
Urinary incontinence
Vesicovaginal fistula
May be mistaken for the fluid

36. Experimental Test(1)
The Nitrazine test uses pH to distinguish amniotic fluid from urine and vaginal secretions, the paper turns dark blue in response to the amniotic fluid
Amniotic fluid is quite alkaline having a pH above 7.0, but vaginal secretions in pregnancy usually have pH values of less 6.0

37. Experimental Test(2)
The “fern” test : placing a sample on a microscopic slide, air drying, and examining for ferning
The amniotic fluid does fern
The other fluid does not fern

38. Risk of PROM Preterm labor: 75%
Intrauterine infection(chorioamnionitis, 30-50% of case)
Puerperal infection

39. Fetal and neonatal complications
Fetal and neonatal pneumonia, sepsis
Neonatal respiratory distress syndrone
Neurologic dysfunction
Intracranial hemorrhage
Prolapse of umbilical cord
Abruptio placenta

40. Evaluation
The gestational age( LMP, ultrasound and uterus fundal height measurement)
The presence of uterine contractions (abdominal examination)
The amount of amniotic fluid (ultrasound)
Fetal heart rate (FHR monitor)
Fetal maturity (L/S or PG)
The likelihood of chorioamnionitis (white blood cell count)
The likelihood of prolapse of umbilical cord

41. Management(1) Conservative expectant management
Management of chorioamnionitis
Tocolytic therapy
Use of corticosteroids
Labor and delivery
Surfactant therapy

42. Management(2)
If PROM occurs at term(37 weeks’ gestational age or more), awaiting the onset of spontaneous labor for 12-24h should be considered, because spontaneous labor will ensue in 90% of patients within 24 hours
If the time from PROM to the inset of labor exceeds 24h, induction of labor should be considered by oxytocin
If the evaluation suggests intrauterine infection or chorioamnionitis, antibiotic and delivery are indicated and the antibiotic prescribed should have a broad spectrum of coverage
If the infant is a preterm breech, and the onset of PROM occurs after 30 weeks’ of gestational, possibly by ceasarean delivery

43. Management(3)
If the gestational age is less 30 weeks’, vaginal deliverly should be chosen
If the fetus is significantlypreterm and the absence of infection, expectant management is generally chosen

44. Management(4) Patients must be assessed carefully
Uterine tenderness daily
Electronic fetal monitoring used frequently
Fetal movement monitoring by the mother
Frequent ultrasound assessment helps to determine amniotic fluid
Frequently WBC counts, usually daily for several days
Antibiotic should be used and antibiotic therapy may prolong the latency period after preterm PROM and improve the perinatal outcome

45. Management(5)
To enhance fetal pulmonary matrurity in patients with preterm PROM
Corticosteroid therapy (such as betamethasone and dexamethasone) is generally recommended in patients whose gestational age is 34 weeks’ or less

46. Thank you!