Comparison 2. Nitric oxide donors versus any betamimetic.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Prolongation of pregnancy greater than 24 hours	2	264	Risk Ratio (M‐H, Fixed, 95% CI)	0.94 [0.82, 1.08]
2 Prolongation of pregnancy greater than 48 hours	3	420	Risk Ratio (M‐H, Fixed, 95% CI)	0.96 [0.87, 1.05]
3 Prolongation of pregnancy greater than 7 days	5	679	Risk Ratio (M‐H, Random, 95% CI)	1.03 [0.92, 1.15]
4 Prolongation of pregnancy greater than 14 days	2	365	Risk Ratio (M‐H, Random, 95% CI)	1.07 [0.82, 1.39]
5 Birth prior to 37 completed weeks	5	679	Risk Ratio (M‐H, Random, 95% CI)	0.73 [0.50, 1.05]
6 Birth prior to 34 completed weeks	2	365	Risk Ratio (M‐H, Random, 95% CI)	0.71 [0.36, 1.42]
7 Birth prior to 32 completed weeks	1	233	Risk Ratio (M‐H, Fixed, 95% CI)	1.00 [0.54, 1.85]
8 Caesarean section	2	283	Risk Ratio (M‐H, Fixed, 95% CI)	0.87 [0.53, 1.43]
9 Adverse effects	1	132	Risk Ratio (M‐H, Fixed, 95% CI)	0.45 [0.30, 0.68]
10 Headache	3	349	Risk Ratio (M‐H, Random, 95% CI)	4.35 [0.91, 20.71]
11 Dizziness	1	191	Risk Ratio (M‐H, Fixed, 95% CI)	1.55 [0.26, 9.06]
12 Palpitations	2	323	Risk Ratio (M‐H, Fixed, 95% CI)	0.06 [0.01, 0.30]
13 Shortness of breath	2	217	Risk Ratio (M‐H, Fixed, 95% CI)	0.09 [0.02, 0.46]
14 Nausea	3	349	Risk Ratio (M‐H, Fixed, 95% CI)	0.47 [0.22, 0.98]
15 Tachycardia	2	323	Risk Ratio (M‐H, Fixed, 95% CI)	0.03 [0.01, 0.10]
16 Chest pain/tightness	2	323	Risk Ratio (M‐H, Fixed, 95% CI)	0.12 [0.02, 0.64]
17 Adverse effects leading to treatment cessations	1	132	Risk Ratio (M‐H, Fixed, 95% CI)	0.05 [0.00, 0.86]
18 Maternal pulmonary oedema	1	191	Risk Ratio (M‐H, Fixed, 95% CI)	0.34 [0.01, 8.34]
19 Death unrelated to congenital abnormalities	1		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
19.1 In utero	1	191	Risk Ratio (M‐H, Fixed, 95% CI)	0.34 [0.01, 8.34]
19.2 In first 28 days of life	1	191	Risk Ratio (M‐H, Fixed, 95% CI)	2.06 [0.19, 22.38]
19.3 After 28 days	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
20 Use of mechanical ventilation	1	132	Risk Ratio (M‐H, Fixed, 95% CI)	0.42 [0.11, 1.54]
21 Chronic lung disease	1	238	Risk Ratio (M‐H, Fixed, 95% CI)	1.03 [0.43, 2.51]
22 Admission of infant to neonatal intensive care unit	2	181	Risk Ratio (M‐H, Fixed, 95% CI)	0.50 [0.31, 0.80]
23 Birthweight	2	182	Mean Difference (IV, Fixed, 95% CI)	440.39 [237.35, 643.44]