PRETERM LABOUR

1. PRETERM LABOUR
-DR.DIVYA JAIN

2.  Preterm labor (PTL) is defined as the
onset of labor after the gestation of
viability i.e.20 weeks, and before 37
completed weeks of pregnancy with
cervical changes.
(ACOG JUNE 2016)

4. Incidence
Overall incidence of PTL : 6 %
- 10 %
 Spontaneous : 40 – 50 %
 PPROM : 25 – 40 %

5. Why has preterm birth
decreased?

6. Does prenatal care
decrease
preterm delivery?

7. RISK FACTORS
Maternal factors :
 Previous preterm delivery .
 Low socioeconomic status .
 Maternal age <18 years or >40 years .
 Preterm premature rupture of the
membranes .
 Maternal complications (medical or
obstetric) .
 Lack of prenatal care .
 Smoking.

8. Uterine causes :
 Myomata (particularly submucosal )
 Uterine septum .
 Bicornuate uterus .
 Cervical incompetence .
 Multiple gestation
 Polyhydroamnios
Placental causes :
 Abnormal placentation

9. Infectious factors :
 Genital :
Bacterial vaginosis , Chlamydia, GBS,
Mycoplasmas
 Intra-uterine :
1)Ascending (from genital tract)
2) Transplacental (blood-borne)
3)Transfallopian (intraperitoneal)
4)Iatrogenic (invasive procedures)
 Extra-uterine :
Pyelonephritis,Malaria,Typhoid fever, Pneumonia
Listeria , Asymptomatic bacteriuria

10. PATHOGENESIS OF
PRETERMLABOUR

12. Diagnosis
 Occurrence of regular uterine
contractions with or without pain (at
least one in every 10 minute.)
 Cervical changes – effacement >80%
and dilatation> 1cm.
 Length of cervix <2.5cm and funelling
of the internal os.
 Pelvic pressure, backache and or
vaginal discharge or bleeding.

13. Tocodynamometry to evaluate for
the
presence of uterine contractions
contractions

14. Speculum examination to assess for
ruptured membranes or bleeding

15. Laboratory evaluation for
urinalysis & culture

16. FFN testing
 High negative predictive value
 More than 99% of symptomatic patients
with a negative fFN did not deliver within 14
days
 Cannot be performed with:
1. Vaginal bleeding
2. Ruptured membranes
3. After recent intercourse
4. After vaginal examination
5. After transvaginal ultrasound

17. Sonography
 Cervical length
 Internal os diameter
 Presence or absence of funelling –
funnel length and width, percentage
funelling
 Pathology

18. PREVENTION
Primary prevention :
 Aim :
lower the prevalence of premature labor by
improving maternal health in general and
by avoiding risk factors before or during
pregnancy
 Measures :
1- Smoking cessation .
2- Nutritional counseling .
3- lower workload for women with stressful
jobs

19. Secondary prevention
 Aim :
Early identification of pregnant women at a risk
of preterm labor and help them to carry their
pregnancies to term.
 Measures :
1- Self-measurement of the vaginal pH for B.V.
2- Cervix length measurement by TVS .
(The accepted cutoff value for cervix length is ≤
25mm before GW 24 )
3- Cerclage and complete closure of the birth
canal
4- Progesterone supplementation

20. Is progesterone our new
silver bullet?

21.  Progesterone is a hormone that inhibits the
uterus from contracting. It is involved in
maintaining pregnancy, especially early in
gestation.
 Progesterone has been recommended for
pregnant women with prior preterm birth.
 Dose-
1) 17-OH Progesterone caproate :250 mg im
weekly
2) Micronized progesterone :200 mg vaginally

22.  A woman with a singleton gestation and a
prior spontaneous preterm singleton birth
should be offered progesterone
supplementation starting at 16–24 weeks of
gestation, regardless of transvaginal
ultrasound cervical length, to reduce the risk
of recurrent spontaneous preterm birth.
 Vaginal progesterone is recommended as a
management option to reduce the risk of
preterm birth in asymptomatic women with a
singleton gestation without a prior preterm
birth with an incidentally identified very short
cervical length less than or equal to 20 mm
before or at 24weeks of gestation.
RECOMMENDATION (ACOG 2012)

23. Prophylactic cerclage
 Cerclage is effective treatment for short
cervical length(less than 15-25mm) with
history of preterm birth.
 Cerclage is indicated in history of cervical
injury, progressive cervical shortening
<25mm despite
progesterone
therapy.

25. History of preterm birth
Prescribe 17- OHP, 250 mg IM weekly from
16 to 37 weeks
Measure TVCL every 14 days rom 16–24
wk of gestation, every 7 days, if CL<30 mm
If TVCL <25 mm before24 wk of gestation:
1. Consider CERCLAGE
(especially if patient had prior spontaneous
preterm
birth at <28 wk or if membranes are visible)
2. Continue progesterone

26. Treatment
 Inhibition of uterine contractions with
tocolytics
 Corticosteroids to induce fetal lung
maturation
 Treatment of infection with antibiotics
 Magnesium sulfate for neuroprotection
(24 and 32 weeks)
 Bed rest and hospitalization.

27. Tocolysis
 Aim of tocolysis :
Suppress uterine contractions and delay
preterm delivery to :
1-allow in-utero transfer to an appropriate
level facility .
2-allow for the administration of
corticosteroids.

28. Contraindications :
• Labour is too advanced
• In utero fetal death
• Lethal fetal anomalies
• Suspected fetal compromise
• Placental abruption
• Suspected intra-uterine infection
• Maternal hypotension: BP < 90 mmHg
systolic
Relative contraindications :
• pre-eclampsia .
• placenta praevia .

29.  Tocolytic drugs that are used in clinical
practice
1) Calcium antagonists . ( Nifedipine )
2) Oxytocin-receptor antagonist
(Atosiban)
3) NO donors . ( Nitroglycerin)
4) Betamimetics . ( Terbutaline &
Ritodrine )
5)Magnesium sulfate . ( MgSO4 )

30. Neuroprotection
 MgSO4 reduces the severity and risk
of cerebral palsy if administered when
birth is anticipated before 32 weeks of
gestation.
 4gm loading dose followed by1gm/hr
for 12 hours
(RCOG 2013)

31. Corticosteroids
 Antenatal corticosteroids are associated
with a significant reduction in rates of
RDS, NEC and IVH.
 Two 12 mg doses of betamethasone
given IM 24 hours apart, Or Four 6 mg
doses of
dexamethasone given IM 12 hours apart.
 MOA of steroids.
1. Stimulates type II pneumocyctes to
produce
surfactant.
2. Accelerated maturation of fetal
intestines

32. Antibiotics
 All patients in preterm labor are
considered at high risk for neonatal
GBS sepsis and should receive
prophylactic antibiotics regardless of
culture status.
 CDC Advises Screening All Pregnant
Women for GroupB Strep 35-37weeks
 The goal of this strategy is to prevent
neonatal sepsis, and not to prevent
preterm birth.
(ACOG 2012 GUIDELINES)

33. In cases of suspected
chorioamnionitis,
determination of CRP is useful.
Value < 0.9 mg/dl- continue
expectant management.
Value between 0.9-1.6- repeat in
12-24 hrs depending on clinical
situation.
Value of 3-4 mg/dl-almost
certainly indicative of infection.

34.  The decision to place a rescue suture should be
individualised, taking into account the gestation at
presentation, as even with rescue cerclage the risks of
severe preterm delivery and neonatal mortality and
morbidity remain high.
 Insertion of a rescue cerclage may delay delivery by a
further 5 weeks on average compared with expectant
management/bed rest alone. It may also be associated
with a two-fold reduction in the chance of delivery
before 34 weeks of gestation. However, there are only
limited data to support an associated improvement in
neonatal mortality or morbidity.
 Advanced dilatation of the cervix (more than 4 cm) or
membrane prolapse beyond the external os appears to
be
associated with a high chance of cerclage failure.
RESCUE CERCLAGE (RCOG 2012)