Preterm Labour and

PPORMDr. Yasir KatibMBBS, FRCSCPerinatologest

Outline

• Definition• Burden of Illness• Etiology & Risk Factors• Diagnosis• Management

– ?tocolytics– ?antibiotics– steroids

Preterm Labour: Definition

• Regular uterine contractions + progressive cervical dilatation and/or effacement at < 37 weeks GA

Burden of Illness: Incidence

• Preterm delivery occurs in 12% pregnancies

• 3-4% were <34 weeks

• Those > 34 weeks born in tertiary care centres have survival rates = term

• Long-term sequelae mainly in those born < 34 weeks

• 70-80% occur spontaneously

Burden of Illness: Significance

• Preterm birth accounts for 75% of Perinatal mortality

• Long-term sequelae include:– CNS & neurodeveopmental problems– respiratory– blindness and deafness

• Significant physical psychological and financial burdens

Survival in Extreme Preterm Delivery

0%

21%

30%

58%63%

86%91%

0%

16%

43%

55%

63%

77%

87%

22 23 24 25 26 27 28

Gestational Age at Birth (weeks)

0%

20%

40%

60%

80%

100%

% S

urvi

val

MUMC 83 - 88 n=464 BCWCH 83 - 89 n=1024

Long-term Morbidity of Extreme PTD

44%

31%27%

22%

11% 9%

23 24 25 26 27 28

Gestational Age at Birth (weeks)

0%

10%

20%

30%

40%

50%MUMC < 29 weeks GA 1983 - 1988 n = 464

Etiology & Risk Factors

• Idiopathic• PPROM• Antepartum hemorrhage• Chorioamnionitis• Multiple pregnancy/polyhydramnios• Incompetent cervix/uterine anomaly• Maternal disease• Fetal Anomaly

Prevention

• No benefit has been demonstrated by attempts to prevent PTL with:– social interventions– bed rest– methods of cervical assessment– medications including betamimetics, magnesium, calcium

• May be some increase in gestation with:– fish oil– progesterone injections– (need further study of both to show benefit)

Diagnosis

• Establish Due Date– Naegele’s Rule– U/S

• 7-12 weeks: +/- 5d

• 13-21 weeks: +/- 1wk

• 22-30 weeks: +/- 2wk

• 30+ weeks: +/- 3wk

• (document clearly on assessments!)

Diagnosis

• History of contractions / risk factors

• Abdo exam for contractions

• Cervical exam – serial if necessary

• 20-50% preterm labour diagnosis is incorrect

• Vaginal fibronectin

• Cervical U/S

Management

• Four Objectives:– 1. Early diagnosis– 2. ID and treat cause if possible– 3. Attempt to arrest Labour when appropriate– 4. Minimize neonatal morbidity and mortality

Management

• Medications

1.MgSO4

2.Ca channel blockers

3.Cyclo-oxygenase inhibitors

4.Oxytocin receptors antagonists

5.Nitric oxcide

Arresting Labour

• Note: <40% patients in preterm labour are candidates for tocolysis

• Goal of tocolysis:– get 48 hrs for steroids to have effect– transport

Tocolysis

• When NOT to tocolyse:– significant vaginal bleeding– suspected fetal asphyxia– intraamniotic infection– IUFD or lethal anomaly– maternal indication– imminent delivery

Tocolysis: Options

• ECPC:– no effect:

• fluid bolus

• ethanol

• sedation

• magnesium sulphate

Tocolysis

• ECPC:– Some effect:

• betamimetics

• calcium channel blockers

• indomethacin

• antimicrobials

• oxytocin antagonists

Antimicrobials: ORACLE II

• Kenyon et al. Lancet 2001 Mar 31;357(9261):989-94– Methods:

• multicentre randomised controlled trial• 6295 women in preterm labour (diagnosis left to individual

clinician) w/ IM, no evid infection & “substantial uncertainty as to whether antbiotics should be prescribed”

• randomized to:– erythromycin– co-amoxiclav– both– placebo

ORACLE II

• Conclusion:– Abx should not be routinely prescribed in PTL

w/o evidence of infection or PPROM

Effect of Corticosteroids on Neonatal Effect of Corticosteroids on Neonatal OutcomesOutcomes

RDS

IVH

NEC

Perinatal Infection

Neonatal Death

0.1 1 10Odds Ratio (95% Confidence Interval)

Crowley CCPC Review No. 02955

Recommendations: NIH

• NIH Consensus Statement JAMA Feb. 1, 1995 273:5:411-417.– fetuses 24-34 weeks w/ threatened PTL candidates for

corticosteroids– pts eligible for toco should be eligible for steroids– Tx: betamethasone 12mg IM Q 24hr x 2

• Dexamethasone 6 mg IM Q 12 hr x 4

– Max benefit 24 hr – 7d, but..– Give even if delivery anticipated w/in 24 hrs b/c some

still beneficial

Upper Gestational Limit

• NIH 1995: give steroids to 24-34wks (adopted by SOGC 1995)

• ALARM: 34-36 wks

• UK Royal College of Obs and Gyn: up until 36 wks

20 24 28 32 36 40

Gestational age (weeks)

0

20

40

60

80

100

RD

S (

%)

RDS - Incidence

RDS: NNT

GA (wks) NNT 95% CI

< 31 4 2, 17

31-34 15 10, 31

> 34 145 25, infinite

GBS PROPHYLAXIS

• The benefits of group B streptococcal (GBS) prophylaxis are well established.

• Intrapartum prophylaxis should be initiated in any patient with an unknown GBS status or a history of a positive culture during the present pregnancy.

• Treatment is not indicated if there was a recent negative anovaginal culture

Universal GBS culture at 35-37wks gestation

GBS prophylactic intrapartum antibiotics

Antibiotics recommended

Not recommended

Prior newborn with GBS disease

Prior documented GBS bacteriuria

GBS positive culture during pregnancyGBS unknown:

PTL < 37weeks

ROM > 18hours

Intrapartum fever > 38oC

Previous pregnancy with positive GBS screening culture

Planned C/S in absence of labor or ROM

Negative GBS screening culture in late gestation regardless of intrapartum risk factors

CDC RECOMMENDATIONS

The effect of antibiotics on GBS

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

< 1hr 1 - 2hr 2 - 4hrs > 4hrs

Time

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Take home points

• Accurate diagnosis key– Dating– Really labour?

• Tocolysis (where appropriate)– choices

• Ca channel blocker

– goals:• give corticosteroids (once)• transfer to appropriate level facility

• To reduce neonatal mortality & morbidity:– Steroids

THANK YOU