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Background
Preterm
birth occurs in up to 6% to 10% of all births and is the major
complication of pregnancy associated with perinatal mortality and
morbidity. Previous preterm delivery is a strong predictor for preterm
labour, and the earlier the birth, the more likely it is to be repeated
at the same gestation. In the acute setting, betamimetics can decrease
contraction frequency or delay preterm birth by 24 to 48 hours.
Objectives
To
assess the effectiveness of prophylactic oral betamimetics for the
prevention of preterm labour and birth for women with singleton
pregnancies at high risk of preterm delivery.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (October 2010) and reference lists.
Selection criteria
Randomised
controlled trials in singleton pregnancies at high risk of preterm
labour comparing prophylactic oral betamimetics with placebo or any
intervention with the specific aim of preventing preterm birth.
Data collection and analysis
Two authors independently assessed trial quality and extracted data.
Main results
One
trial (64 singleton pregnancies) was included. The trial compared the
oral betamimetic agent isoxuprine with placebo. No difference was seen
for perinatal mortality rate (risk ratio (RR) 4.74, 95% confidence
interval (CI) 0.50 to 45.00). There was no evidence of an effect of oral
betamimetic agents in reduction of spontaneous onset of preterm labour
(RR 1.07, 95% CI 0.14 to 8.09) or preterm birth, less than 37 weeks'
gestation. There was no significant association between the use of oral
betamimetics and side effects sufficient to stop therapy (RR 2.51, 95%
CI 0.59 to 10.76). No differences were found for infant outcomes;
birthweight less than 2500 grams (RR 1.74, 95% CI 0.44 to 6.87) or
neonatal death (RR 4.74, 95% CI 0.50 to 45.00). This trial had adequate
methodological quality; however the sample size was inappropriate to
determine any significance in neonatal outcome differences between the
treatment groups.
Authors' conclusions
There
is insufficient evidence to support or refute the use of prophylactic
oral betamimetics for preventing preterm birth in women at high risk of
preterm labour with a singleton pregnancy.
Prophylactic oral betamimetics for preventing preterm labour in singleton pregnancies
There are insufficient data on use of betamimetic drugs given by mouth to reduce preterm birth in women at increased risk of preterm labour and carrying one baby.Women sometimes go into labour early and babies are born prematurely (before 37 weeks). These babies are at increased risk of health problems and the earlier a baby is born the higher the risk. Babies born before 32 weeks have considerable problems, with those born before 28 weeks being at most risk. These babies can suffer from problems with breathing, bleeding, gut and intestines. They are also at increased risk of cerebral palsy or long-term handicap, and some babies do not survive even the early weeks. Babies need special care, sometimes intensive care, and this can be quite traumatic for parents. Preterm birth occurs in around 6% to 10% of births. Many interventions have been assessed to try to improve outcomes for these babies; this review looks at a group of drugs called betamimetics given by mouth in women at increased risk and carrying one baby. These drugs aim to reduce and inhibit labour contractions. However, they do have side effects which include nausea, vomiting, tremor, headaches and shortness of breath. The review of studies found only one trial involving 64 women. There is therefore insufficient evidence to support the use of these drugs to reduce preterm labour and birth.
