MATERNAL AND EARLY CHILD HEALTH

Health Evidence Bulletins - Wales

Date of Completion: 9.1.98

The contents of this bulletin are likely to be valid for approximately one year, by which time significantly new research evidence may become available


13. Premature Labour

(Users are advised to consult the supporting evidence for a consideration of all the implications of a recommendation)

Preterm labour may follow preterm rupture of membranes, or become established with intact membranes.
13.1 PRETERM LABOUR  
The Statements The Evidence
13.1a. It is of proven value to administer corticosteroids to women in premature labour with intact membranes between 24 and 36 weeks (2 doses of betamethasone [12 mg im] 24 hours apart, or 4 doses of dexamethasone [6 mg im] 12 hours apart) to promote fetal lung maturation before preterm delivery (NNT = 5 to prevent one case of respiratory distress in babies of less than 31 weeks gestation)(i).
(Health gain notation - 1 "beneficial")
i. Royal College of Obstetricians and Gynaecologists. Guideline No.7. Antenatal corticosteroids to prevent respiratory distress syndrome. London: Royal College of Obstetricians and Gynaecologists, April 1996
(Type I evidence - review including one large meta-analysis)
13.1b. No evidence is yet available to support or condemn the repeated use of corticosteroids (one week after the initial course) in those women who remain undelivered and at continued risk of preterm birth. Controlled trials are needed(i).
(Health gain notation - 4 "unknown")
i. Crowley, P. Corticosteroids prior to preterm delivery. Cochrane Library Issue 4, September 1997
(Type I evidence - systematic review)
13.1c. The indications for the use of ritodrine (or other beta-mimetics) is restricted to the management of uncomplicated preterm labour between 24 and 33 weeks’ gestation (i).
(Health gain notation - 2 - "likely to be beneficial")
caveat: Trials suggest that the number of women delivering within 48 hours of commencement of treatment is significantly reduced but no reduction in perinatal mortality or serious morbidity was detected through use. However, short term use enables the time gained before delivery to be used to administer corticosteroids and arrange for transfer to a centre with intensive care facilities. Strict adherence to recommended dosage is required to avoid side effects, including pulmonary oedema and myocardial ischaemia.
i. Royal College of Obtsetricians and Gynaecologists. Guideline No.1A. Beta-agonists for the care of women in preterm labour. London: Royal College of Obstetricians and Gynaecologists, January 1997

(Type I evidence - review including a meta-analysis)

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13.1d. Short term indomethacin to stop preterm labour may be beneficial but, because of the known and unknown side-effects (such as bronchopulmonary dysplasia), more and better controlled data are needed to assess its value in preterm labour(i).
(Health gain notation - 4 "unknown")
i. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 pp. 716-721
(Type I evidence - systematic review. Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. pp. 166-168)
13.1e. After the successful treatment of acute preterm labour, maintenance therapy with oral b -agonists (ritodrine or tertutaline) does not decrease the risk for preterm delivery (OR 1.09), recurrent labour (OR 1.05) or respiratory distress syndrome (OR 0.91). They also do not increase the time to delivery or birth weight(i). (Health gain notation - 5 "unlikely to be beneficial") i. Macones GA, Berlin M, Berlin JA. Efficacy of oral beta-agonist maintenance therapy in preterm labour: a meta-analysis. Obstetrics and Gynaecology. 1995; 85(2):313-7.
(Type I evidence - meta-analysis)
13.1f. There is a trade-off between beneficial and adverse effects in the use of cervical cerclage for women at risk of preterm birth because of cervical incompetence(i).
(Health gain notation - 3 "trade-off between beneficial and adverse effects)
caveat: A small proportion of women will benefit (especially those who have had two or more past pregnancies which have ended too early) but there are hazards associated with the surgery and the risk of stimulating uterine contractions.
i. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 pp. 633-645
(Type I evidence - systematic review. Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. p. 162)

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13.1g. There is some evidence that infection is a causal agent in a proportion of cases of premature labour. An ongoing trial should resolve whether antibiotics are effective in the prevention of preterm birth(i).
(Health gain notation - 4 "unknown")
i. Oracle Trial: Contact the Medical Research Council, London.
13.1h. The following strategies are of unknown benefit (i):
  • Routine cervical assessment for identification of women at risk of preterm birth;
  • The use of magnesium sulphate, calcium antagonists or oxytocin antagonists in suppression of preterm labour.

(Health gain notation - 4 "unknown")

i. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 Chapter 44, particularly pp. 694-695, 730-745
(Type I evidence - systematic review for MgSO4; Types II-V evidence for other interventions. Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. pp. 163, 168-170)
13.1i. Two randomised controlled trials of adding thyroid trophic releasing hormone (TRH) to corticosteroids to promote fetal lung maturation have shown no benefits (i, ii).
(Health gain notation - 5 "unlikely to be beneficial")
i. National Institute of Health study (USA) submitted to the New England Journal of Medicine (Ballard et al).
ii. Chilean trial: American Journal of Obstetrics and Gynaecologists (in press)
13.1j. The following strategies are unlikely to be beneficial in the management of preterm delivery (i):

Routine elective forceps;

Routine use of episiotomy.

(Health gain notation - 5 "unlikely to be beneficial")

i. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 pp. 1283-1284
(Type I evidence - systematic review of limited trials. Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. p. 281)

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13.1k. The use of ethanol to stop preterm labour is likely to be ineffective or harmful (i).

(Health gain notation - 6 "likely to be ineffective or harmful")

i. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 pp. 721-727
(Type I evidence - systematic review of limited trials. Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. p. 168)
13.1l. Two strategies have been suggested to promote early recognition of preterm labour: Educational programs and home uterine activity monitoring. Neither have an effect on neonatal survival, low birthweight rates or preterm delivery rates while, in the case of educational programmes, there is a doubling of the risk of being diagnosed as having preterm labour during pregnancy (i,ii).

(Health gain notation - 6 "likely to be ineffective or harmful")

i. Hueston WJ, Knox MA, Eilers G, Pauwels J, Lonsdorf D. The effectiveness of preterm-birth prevention educational programs for high-risk women: a meta-analysis. Obstetrics and Gynaecology. 1995; 86(2): 705-712
(Type I evidence - meta-analysis of randomised controlled trials in Medline);
ii. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 p. 695
(Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. p. 162)
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13.2 PRETERM PRE-LABOUR RUPTURE OF MEMBRANES  
The Statements The Evidence
13.2a. Corticosteroid administration (see statement a.) after prelabour rupture of membranes preterm is likely to be beneficial with advantages greater than the added risk of infection (i,ii).

(Health gain notation - 2)

i. Crowley, P. Corticosteroids prior to preterm delivery. Cochrane Library Issue 4, September 1997
(Type I evidence - systematic review);
ii. Royal College of Obstetricians and Gynaecologists. Guideline No.7. Antenatal corticosteroids to prevent respiratory distress syndrome. London: Royal College of Obstetricians and Gynaecologists, April 1996
(Type I evidence - review including one large meta-analysis)
13.2b. An initial vaginal culture should be taken after prelabour rupture of membranes(i).

(Health gain notation - 2 "likely to be beneficial")

i. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 p. 689
(Type V evidence - expert opinion. Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. p. 150)
13.2c. Antibiotics given routinely subsequent to preterm (27-33 weeks) rupture of membranes reduce the odds of early delivery and infection although they have not been proven to affect the incidence of respiratory distress or mortality in the neonate (i).
(Health gain notation - 2 "likely to be beneficial")
i. Divers M. Infection and preterm labour. PACE review No. 95/12. London: Royal College of Obstetricians and Gynaecologists, 1995.
(Type I evidence - systematic review)

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13.2d. In populations with a high prevalence of Group B streptococci carriers, either screening for the organism or routine antibiotic treatment should be adopted as standard care following pre-labour rupture of membranes(i).
(Health gain notation - 2 "likely to be beneficial")
i. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 p. 689
(Type V evidence - expert opinion. Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. p. 150)
13.2e. It is likely to be beneficial to allow labour to progress after prelabour rupture of membranes preterm depending on the stage of pregnancy (i).

(Health gain notation - 2 "likely to be beneficial")

i. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 pp. 680-682
(Type II evidence - Two trials. Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. pp. 153-154)
13.2f. If there are signs of intrauterine infection following prelabour rupture of membranes, antibiotic treatment should be started and delivery effected. A skilled neonatologist should be present at the birth (i).
(Health gain notation - 2 "likely to be beneficial")
i. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 p. 689
(Type V evidence - expert opinion. Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. p. 159)
13.2g. The delivery of a very preterm baby (32 weeks or less) should be in a centre with neonatal intensive care facilities and in the presence of an appropriately experienced paediatrician. In utero transfer is preferable(i).
At 33 weeks the need for transfer should be weighed against facilities and staff available(ii).
(Health gain notation - 2 "likely to be beneficial")
i. Chalmers I, Enkin M, Keirse MJNC. Effective care in pregnancy and childbirth. Oxford: Oxford University Press, 1989 p. 1286
(Type V evidence - expert opinion. Summary in Enkin M, Keirse MJNC, Renfrew M, Neilson J. A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press. 1995. pp. 277, 283);
ii. Internal Review Group (See Contributors)
(Type V evidence - expert opinion)
13.2h. Trials of antenatal administration of phenobarbital to women at risk of very preterm birth have shown a minimal reductionin the incidence of intraventricular haemorrhage with an increase in the incidence of respiratory distress and a requirement for ventillation (i,ii,iii).

(Health gain notation - 5 "unlikely to be beneficial")

i. Horbar JD. Prevention of periventricular-intraventricular hemorrhage. In: Effective care of the newborn infant. Editors. J Sinclair and MB Bracken. Oxford: Oxford University Press, 1992 pp.565-566
(Type I evidence - systematic review)
ii. Doyle L. Antenatal phenobarbitone and neonatal outcome. Lancet 1996; 348: 975-6
(Type I evidence - review including a meta-analysis and several trials)
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Health Evidence Bulletins: Wales, Duthie Library, UWCM, Cardiff CF14 4XN. e-mail: weightmanal@cardiff.ac.uk