PRETERM LABOR power point presentation

1. PRETERM LABOR & Mgt

2. Session Objective
. Define Preterm Labor
. Describe magnitude of the problem
. List etiology of preterm labor
. Discuss diagnosis, treatment, and prevention
principles

3. PRETERM LABOR
Definition:
 Onset of labor prior to the completion
of 37 weeks (<259 Days from LNMP)
& after the gestational viability(20 wks).

4. Mechanisms of Labor Onset
Labor occurs when the uterus
converts from a state of
containment to an environment
that attempts to expel the fetus.
In theory, pathologic activation of
the normal parturition process
results in preterm labor and delivery

5. Pathophysiology
The pathophysiologic mechanisms that lead
to the onset of preterm labor are complex
and multifactorial. But it is assumed to be
a result of the concomitant activation or a
cascade of the following events
- Functional progesterone withdrawal
- Increase in corticotrophin releasinghormone(CTRH)
- Premature decidual activation
- Increased prostaglandin production
- Oxytocin initiation
- Increased cytokine production.

6. Incidence
. varies from 5-15%
. It is the number 1 cause of neonatal
morbidity and mortality and causes 75% of
neonatal deaths that are not due to
congenital anomalies

7. Survival in Premature Infants
26 wks – 80%
27 wks – 90%
28-31 wks – 90 to 95%
32-33 wks – 95%
34-36 wks –approaches
term survival rates

8. Etiology
The cause of preterm labor in
50% of pregnancies is idiopathic.
Other known causes are
multifactorial and associated with
different factors including
Maternal & Fetal factors.

9. Maternal factors
General conditions
Age. <18, >40
Short stature
Weight < 45 Kg
Strenuous work during pregnancy
Nutritional status (obesity/ malnutrition)
Race
Low socioeconomic status

10. Anemia, Asthma
Chronic HPN
Infections
 Bacterial vaginosis
 Asymptomatic bacteuria & UTI / GTI
 Pneumonia
 Appendicitis
 Dental infections
Medical & Obstetrical Conditions
Chronic ill health

11. PROM with chorioamnionitis
Previous Hx of PL or induced abortion
APH
PE, Eclampsia
Interval between pregnancies
. intervals shorter than 18 months and longer
than 59 months were associated with
increased risks for preterm labor
Obstetrical Conditions

12. ……..
Congenital abnormalities of the uterus
(septate, unicornuate/ biconuate Ux)
Incompetence of cervix
Substance abuse (tobacco, Alcohol)
Trauma
Genetic
– Many preterm deliveries are familiar

13. Fetal factors
Congenital malformation with
associated hydraminos
Fetal B/G incopatibility (Rh or ABO)
(especially those associated with
hydrops fetalis)
IUFD
Multiple pregnancies

14. Iatrogenic /Elective PL
Due to advance in neonatal care
there is a greater incidence of
iatrogenic or elective PL, e.g. for bad
Ob.hx like Previous SB, PE,E,PP,
IUGR, ….
Miscalculation of GA also
leads to premature
induction of labor

15. In summery, the interplay of causes of
the ‘preterm labor syndrome’
Iatrogenic
infection
Uterine
Preterm labor
Cervical
weakness
Haematogenous
infection
Ascending
infection
Placental
abruption
distention
Maternal stress
Fetal stress
Multiple pregnancy
Decidual
Haemorrhage

16. SIGNS & SYMPTOMS
painful or painless uterine contractions
pelvic pressure
Intermittent abdominal cramping
watery vaginal discharge/Spotting
Lower back pain
Braxton Hicks contractions
– contractions, described as irregular, nonrhythmical, and either
painful or painless, can cause considerable confusion in the
diagnosis of true preterm labor

17. Diagnosis
Preterm labor is a clinical diagnosis. It should
be suspected in any gravida with regular
preterm uterine contractions and is
confirmed with documented cervical change.
The following mentioned procedure &
objective criteria may also be useful in
establishing the diagnosis (fetal fibronectin
and U/S measurement of cervical length).

18. PHYSICAL EXAM
V/S
Hydration stutus
Abdominal – FH (to see the
correlation with period of gestation),
monitoring of contractions & FHR
auscultation.

19. INVESTIGATIONS
CBC
C-reactive protein
U/A
Urine culture & sensitivity
High vaginal swab & culture (especially for
Group B streptococcus), pH & fern test
Speculum exam. to look for any infection &
leaking of liquor

20. Special investigations
Enzyme linked immunosorbent assay(ELISA)
for fetal fibronectin
A swab is taken from posterior fornix/
external cervical os. The presence of
fibronectin in the Cx & vagina after 22
wks & before 37 wks is diagnostic of PL
Exam. of urethral discharge for gonorrhea
Cervical swab exam. for Chlamydia

21. Fetal Fibronectin
- 99% negative predictive value for delivery within 2wks
- Positive predictive value worse, about 30% 22 to35wks

22. Pervaginal exam
- Cx > 3cm dilated & > 80% effaced
- Presence or absence of membranes
- Presentation
Per abdominal U/S
- Fetal well-being
- AFV
- Placental localization
- Fetal presentation
- Cervical length-(<20/25mm- high risk)

23. Transvaginal U/S
- More accurate for cervical length measurement
10th% = 25mm (20 to 30 wks gestation)
80-100% of women who deliver early have Cx<30mm
50% delivery rate within one week ≤15mm

24. Amniocentesis
 To assess fetal lung maturity
If suspicion of intrauterine infection
exists, amniotic fluid exam. is done.
Ѳ WBC count
Ѳ Glucose (low in case of infection)
Ѳ Interleukin-6 concentration (high in
case of infection)
Ѳ Gram stain & culture
Ѳ Lecithin/Sphingomyelin(L/S) ratio for
maturity

25. Sterile speculum examination
- pH
- Fern
- Pooled fluid
- Fibronectin swab
- Cultures for chlamydia, N.gonorrhea GBS
Chlamydia causes inflamation, rupture of the cell and scar
N.Gonorrhea causes inflammatinof the cell but not causes rupture and scar

26. Criteria to document preterm labor:
# Contractions 4/20min or 8/60 min
plus
progressive change in the cervix
# Cervical dilatation >1 cm
# Cervical effacement of ≥80 %

27. MANAGEMENT
The cornerstone of treatment is to
avoid delivery prior to 34 wks.
1. Amniocentesis to detect infection
2. Steroid therapy to enhance fetal
lung maturation
3. Antimicrobials
4. Emergency or rescue cerclage

28. A/ INHIBITION OF PRETERM LABOR
1. Bed rest
2. Hydration and sedation
With adequate hydration and bed rest, uterine
contractions cease in approximately 20% of patients.
These patients, however, remain at high risk for recurrent
preterm labor.
If the patient does not respond to bed rest and
hydration, tocolytic therapy is instituted, provided
that there are no contraindications.

29. UTERINE TOCOLYTIC AGENTS
MAGNESIUM SULFATE
NIFEDIPINE
PROSTAGLANDIN SYNTHETASE INHIBITORS
BETA MIMETICS
- ISOXUPRINE, RITODRINE, TERBUTALINE

30. Magnesium sulfate:
Drug of choice for initiating tocolytic
therapy.
Drug of choice for patients with DM or HF.
Side effects : loss of DTRs, respiratory depression,
cardiac arrest, Hypotension, Oliguria
Acts at the cellular level by competing with
calcium for entry into the cell at the time of
depolarization.Successful competition results in
an effective decrease of intracellular calcium
ions, resulting in myometrial relaxation.

31. ……
Dosage: 4-6 g IV bolus/15 min, ---------->2 -6 g/hr.
A common clinical approach is to start with a 6 g
IV bolus followed by 3 g per hour.
Assess contraindications &
follow for toxicity
Contraindications
- Myasthenia gravis,
- Cardiac impairment,
- Renal impairment

32. Nifedipine (Calcium channel blockers)
Side effects: flushing, headache, dizziness,
hypotension, Tachycardia and peripheral edema.
Decreases the influx of intracellular calcium ions
into myometrial cells, promoting relaxation
Dosage: 20- 30mg loading dse, 10-20 mg po Q4 -8hr

33. Prostaglandin synthase inhibitors
Agents available: aspirin, ibuprofen,
indomethacin, sulindac, ketoralac.
Indomethacin: the most commonly used
agent.
Dosage:50- to 100-mg loading dose, followed
by 25 mg every 6 to 8 hrs for 2-3dys
Side effects: nausea and gastrointestinal upset

34. Beta adrenergic receptor agonist
Agents are : Ritodrine,Terbutaline, Isoxuprine
Parenteral beta agonists
prevent preterm birth for at
least 48 hours facilitating
maternal transport and giving
of steroids
MOA:
reduce intracellular ionized
calcium levels and prevent
activation of myometrial
contractile proteins
SIDE EFFECTS:
• Pulmonary edema

35. Contraindications to Tocolytic Therapy
Severe preeclampsia,
APH
Chorioamnionitis,
IUGR
Fetal anomalies incompatible with life
Fetal demise
Advanced cervical dilatation

36. Recommended Management of
Preterm Labor
The following considerations should be
given to women in preterm labor:
1. Confirmation of preterm labor
2. For pregnancies less than 34 weeks with
no maternal or fetal indications for delivery, close
observation with monitoring of uterine contractions
and FHR is appropriate, and serial examinations are
done to assess cervical changes.

37. ……
3. For pregnancies less < 34 wks,
glucocorticoids are given for enhancement
of fetal lung maturation.
- Betamethasone 12 mg im daily for 2
dys
OR
- Dexamethasone 6mg im bid for 2 dys

38. ……..
4.Consideration is given for maternal
magnesium sulfate infusion for 12 to
24 hrs to afford fetal neuroprotection.
5. For pregnancies < 34 wks in women who
are not in advanced labor, it is reasonable to
attempt inhibition of contractions to delay
delivery while the women are given
corticosteroid therapy and GBS prophylaxis.

39. ……..
6.For pregnancies at 34 weeks or beyond,
women with preterm labor are monitored
for labor progression and fetal well-being
7.For active labor, an antimicrobial is given
for prevention of neonatal GBS infection.

40. Intrapartum Management
1. Labor
- Continuous electronic monitoring is preferred
- Fetal tachycardia, especially with ruptured
membranes, is suggestive of sepsis

41. …….
2. Prevention of neonatal GBS infections
Either penicillin G or Ampicillin IV Qid
until delivery for women in preterm labor.
3. Delivery
Staff proficient in resuscitative techniques
commensurate with the gestational age of the
newborn and fully oriented to any specific
problems should be present.

42. ……..
 Preterm newborns have
germinal matrix bleeding
that can extend to more
serious intraventricular
hemorrhage
Active management of active-
phase and 2nd stage of labor
4. Prevention of neonatal intracranial hemorrhage

43. Complications of Prematurity
RDS
IVH
NEC
Apnea
PDA
Infection
Jaundice
Hypothermia
Neurobehavioral problem
Retinopathy of prematurity
Anemia
.

44. Prevention of PL
PRIMARY PREVENTION
– Preventing pregnancy in teenagers
– Prevent smoking
– Prevent reprod. TI/ STIs
– Access to FP methods to prevent unwanted &
frequent pregnancies.
– Preconceptional counseling
– Improve the nutrition & general health of the
women
– Decrease factors causing stress

45. SECONDARY PREVENTION
Identification of preg. Women who are risk &
their close surveillance.
Includes:
Pt education to enable them to detect early
symptom of PL (Rhythmic Ux contraction, pelvic
pressure, heavier vaginal discharge/vag. Spotting )
and also instruct to reduce physical & sexual
activity.

46. Medical therapy include tocolytic drugs,
progesteron, cortisone & metronidazole
Progesterone
 It can effectively decrease the
incidence of preterm birth.
17-Hydroxyprogesterone caproate,
250 mg IM wkly from GA of 16-20 wks to
37 wks.
Progesterone vaginal suppositories,
100 mg vaginally daily from 24 to 34
weeks gestational age.

47. …..
Circlage if cervical incompetence is present.

48. References
Manual of Obstetrics, 7th edition
Williams Obstetrics, 22 edition
Current Obstetrics and Gynecology,10th ed
UpToDate online

50. Any Questions?