Seventeen studies met the inclusion criteria with 1184 women and 1232 infants in the intervention group, and 1100 women and 1155 infants in the control group. One study was reported twice (only 1 set of results included in these numbers).
Tocolytics were associated with statistically significant decreases in the likelihood of delivery with 24 hours (OR 0.47, 95% CI: 0.29, 0.77), 48 hours (OR 0.57, 95% CI: 0.38, 0.83), and 7 days (OR 0.60, 95% CI: 0.38, 0.95). Betamimetics, indomethacin, atosiban and ethanol, but not magnesium sulfate, were associated with significant prolongations in pregnancy. Tocolytics were not associated with a statistically significant reduction in births before 30 weeks' gestation (OR 1.33, 95% CI: 0.53, 3.33), before 32 weeks' gestation (OR 0.81, 95% CI: 0.61, 1.07), or before 37 weeks' gestation (OR 0.17, 95% CI: 0.02, 1.62). Only one study of indomethacin showed a statistically significant decrease in preterm births.
Tocolytics were not associated with a statistically significant reduction in perinatal death (OR 1.22, 95% CI: 0.84, 1.78), respiratory distress syndrome (RDS) (OR 0.82, 95% CI: 0.64, 1.07), intraventricular haemorrhage (OR 0.73, 95% CI: 0.46, 1.15), necrotising enterocolitis (OR 0.96, 95% CI: 0.35, 2.65), patent ductus arteriosus (OR 0.82, 95% CI: 0.52, 1.30), neonatal sepsis (OR 1.09, 95% CI: 0.70, 1.68), seizures (OR 1.05, 95% CI: 0.35, 3.14), hypoglycemia (OR 1.36, 95% CI: 0.87, 2.14), or birth weight under 2500 g (OR 0.62, 95% CI: 0.35, 1.09).
Maternal side-effects statistically significantly associated with tocolytic use were palpitations (OR 10.15, 95% CI: 7.42, 13.87), nausea (OR 2.05, 95% CI: 1.47, 2.85), tremor (OR 8.30, 95% CI: 5.79, 11.89), chorioamnionitis (OR 2.88, 95% CI: 1.13, 7.33), hyperglycemia (OR 3.39, 95% CI: 2.35, 4.90), hypokalemia (OR 6.43, 95% CI: 4.53, 9.14), and need to discontinue treatment (OR 10.09, 95% CI: 4.91, 20.74). Tocolytics were not associated with statistically significant increases in pulmonary edema, chest pain, cardiac arrythmias, dyspnea, vomiting, headaches, endometritis, or hypertension.
Betamimetics were associated with increases in most maternal side effects.
There were no maternal deaths reported in any study.