Insert Presenter’s NameDr Uma.TDepartment of Obstetrics and Gynecology SAT Hospital,Government Medical College Trivandrum

Def : Regular painful uterine contractions after 20 wks and before 37 wks

Associated with effacement and dilatation of cervix

Incidence – 20 – 30%Impact – Regarding chance of survival

of preterm neonate- Quality of life achieved.

AETIOLOGYMaternal CharacteristicsAge – Low & HighSocioeconomic status– PoorPhysical Activity Maternal habits & – Cigarette,

addictions Alcohol, Cocaine

Psychological Stress

MATERNAL SYSTEMIC DISEASESRenal Diseases – Acute infection

& asymptomatic bacteruria

Hypertensive disordersMaternal diabetes – HydramniosImmunological

disorder – SLE, APLA syndrome

MATERNAL INFECTIONS

Febrile illnesses – MalariaInfective diseases – Syphilis,

toxoplasmosisChorioamnionitisBacterial vaginosis - PPROM

UTERINE FACTORSUterine MalformationsCervical incompetencePrevious history of abortion &

Preterm birthsPREGNANCY COMPLICATIONSMultiple pregnancyHydramniosPlacenta Praevia or abruptionGENETIC FACTORS

PATHOGENESISExact mechansim not knownFetus plays synergestic role ↑ PG synthesis – stimulated by

intrauterine infection, haemorrhage, overdistension etc.

From decidua & fetal membranes ↑ Cytokines, IL – 6, IL - 1, TNF, PAF

– produced by fetal lungs, kidney

PREDICTION OF PRETERM LABOUR1. Measuring cervical length using TVS

– At 24 wks – Mean cervical length is

35 mm . Shortened cervix had ↑ rate of

preterm labour Requires special expertise2. History of preterm birth3. Fetal fibronectin – in cervicovaginal

secretions4. Ambulatory uterine contraction

testing 5. Maternal Salivary estriol – not used

DIAGNOSISContractions at a frequency of 4 in

20 mts. or 8 in 60 mts.Cervical dilatation more than 1 cm.Cervical effacement of 80% or

greater.

MANAGEMENTDepends on gestational age and neonatal

care facilitiesGestational age between 24 and 34 wks –

administer corticosteroids2 doses of 12 mg betamethasone given

intramuscularly 24 hour apart.If delivery occurs 24 hrs after completion

of betamethasone and within 7 days, chance of respiratory distress less.

MECHANISM OF ACTIONInduces proteins that regulate

biochemical systems in type 2 cells.Increases alveolar surfactant,

compliance and lung volume.Adverse effects – Short termMaternal – Pulmonary edema,

infections, poor diabetic controlFetal – Nil.

Epithelial cell

Structural Developme

nt

Type II

PneumocytesApoprotei

ns

Steroids

Steroids

surfactant

Repeated Doses of Steroids?Not recommended

Adverse effects

1.Chorioamnionitis.2.Cause early onset neonatal sepsis.3.NND.4.Low birth weight.5.Abnormal psychomotor development.

Tocolysis in preterm labourDoes tocolysis prevent preterm labour?No clear evidence improve outcome; only to

complete course of corticosteroids or inuterotransfer

(Evidence A)

Does tocolysis prevent NND and morbidity ?No clear reduction (Evidence

A)

INDICATION FOR TOCOLYSISGestational age less than 37 wks Cervical dilatation less than 3 cmNo history of unclean examination

or evidence of chorio amnionitis.No pregnancy complication like

APH, PE Fetus normal, alive, no signs of

distress.

COMMONLY USED…

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TOCOLYTICSBetadrenergic drugsIsoxuprine, Riltodrine, salbutamol,

terbutalineInhibit uterine contraction by

stimulating myometrial β-2 receptors.Adverse effects due to stimulation of

receptors elsewhere.Maternal hypotension, Tachycardia,

palpitation, fetal Tachycardia.

MAGNESIUM SULPHATEHigh concentration decreases contractilityNot used for this purpose.

PROSTAGLANDIN INHIBITORSAspirin, IndomethacinUse avoided – Premature closure of neonatal

ductus arteriosus and neonatal pulmonary hypertension

CALCIUM CHANNEL BLOCKERSAll smooth muscle activity related to

free calcium in cytoplasmReduction in Calcium inhibits

uterine contraction.Nifedipine – Efficacy not been

adequately studied.

Pre-term Labor in Women with a Past History of PTL

Am J Obstet Gynecol. 1998;178(5):1035–1040.

Fetal fibronectin positive women with a prior history of preterm birth

Estimated recurrence riskof preterm birth <35 weeks’

gestation

Cervical Length ≤25 mm 65%

Cervical Length 26 to 35 mm 45%

Cervical Length > 35 mm 25%Fetal fibronectin negative women with a prior history of preterm birth

Estimated recurrence riskof preterm birth <35 weeks’

gestation

Cervical Length ≤25 mm 25%

Cervical Length 26 to 35 mm 14%

Cervical Length > 35 mm 07%

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Oral Micronized Progesterone Improves Maternal and Fetal Outcomes in Women with a History of PTL

Oral micronized progesterone was associated with

Improved birth weight (2400 g vs. 1890 g, p<0.001)

Lower stay in the neonatal ICU (p<0.001)

More favorable Apgar scores (p<0.001)

J Obstet Gynaecol. 2009;29(6):493–498.Int J Gynaecol Obstet. 2009;104(1):40–43.22

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Reference and study type

Intervention (N)

Mean GA SD

(weeks)

PTB<37 weeks

(%)

PTB≤36 weeks

(%)

PTB≤34 weeks

(%)

PTB≤33 weeks

(%)

PTB≤28 weeks

(%)

Majhi et al.2 (2009), RCT

Vaginal (50)

NR 12.0* NR 4.0 NR NR

None (50) NR 38.0 NR 6.0 NR NR

Rai et al.2 (2009), RCT

Oral (74)36.12.

6*39.2* NR 27.0 2.7* 0

Placebo (74)

34.03.25

59.5 NR 25.7 20.3 4.0

NR=Not reported. *Statistically significant.

Pre-term Labor and Uterine Abnormalities

Women with uterine anomalies have poorer reproductive

outcomes when compared to that of the general population.

Unicornuate uterus is associated with the poorest fetal

survival.

The incidence of preterm deliveries among women with

bicornuate uterus and didelphic uterus has been reported in

as high as one-fourth of the pregnancies

J Womens Health (Larchmt). 2004;13(1):33–39.

Number of pregnancies (n)

Preterm deliveries (n)

Unicornuate uterus

393 43.3% (170)

Didelphic uterus 86 24.4% (21)

Bicornuate uterus

56 25.0% (14)

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Vaginal Micronized Progesterone for Prophylaxis of PTL

– Results from Cetingoz et al.

Arch Gynecol Obstet 2011;283:423–429.

Vaginal progesterone (100 mg) administered between 24 and 34 weeks has the following outcomes in women with

prior pre-term birth, twin pregnancy and uterine malformations

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Placebo (%) Progesterone (%)

Total population

Delivery <37 weeks 40/70 (57.2) 32 of 80 (40)

Delivery <34 weeks 17/70 (24.3) 7 of 80 (8.8)

Preterm labor admission 32/70 (45.7) 20 of 80 (25)

History of PTB

Delivery <37 weeks 17/34 (50) 9 of 37 (24.3)

Delivery <34 weeks 9/34 (26.5) 2 of 37 (5.4)

Preterm labor admission 19/34 (55.9) 11 of 37 (29.7)

Pre-term Labor and Cervical Length – Results from Iams et al.

Even a small decrease in cervical length between the 24th

and 28th weeks of gestation was associated with an

increased risk of preterm birth (relative risk, 2.03; 95% CI,

1.28–3.22)

N Engl J Med. 1996;334(9):567–572.

Measures (at 24 weeks) Relative risk

Cervical length ≤ 25th percentile (30 mm) as compared to > 75th percentile

3.79 (95% CI, 2.32–6.19)

Cervical length ≤ 10th percentile (26 mm) as compared to > 75th percentile

6.19 (95% CI, 3.84–9.97)7

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Progesterone Preserves Cervical Length – Results from O’Brien et al.

Ultrasound Obstet Gynecol 2009;34:653–659.

Intravaginal progesterone preserves cervical length

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NEONATAL CARE

Preterm infants require neonatal intensive care.

If facilities not available, give corticosteroids and refer patient to appropriate higher centre

INTRAPARTUM MANAGEMENT

Proper fetal heart rate monitoringDelivery – RMLE put If poor voluntary efforts in second stage –

Outlet forceps.