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Table A. Summary characteristics of the included studies
Number of
Characteristic Studies References

Study Design RCT 2 10,11
Nonrandomized trial 1 12
Prospective cohort 2 13,14
Retrospective cohort 7 15-21
Case series 2 22,23
Participant Single center sites 9 10-14,20-23
Recruitment Matria database 5 15-19

Funding Industry 2 10,22
Nonindustry 3 14,20,21
Not reported 9 11-13,15-19,23
Comparator* Oral nifedipine 3 15-17
Oral terbutaline 4 11,12,20,21
Oral tocolytics 3 14,18,1
Placebo (saline pump) 2 10,11
No treatment 1 13
No comparison group 2 22,23

Primary Tocolytic IV magnesium sulfate only 1 23
Treatments IV magnesium sulfate and/or 5 10-13,22
other agents
Not reported 8 14-21
Gestation Singletons only 6 10,12,13,15,17,18
Twins only 2 16,19
Singletons and twins 2 11,22
Not reported 4 14,20,21,23
Definition of Labor Not reported 5 15,17-19,21

Risk of Bias** Low 1 10
Medium 7 12,16,17,19,20,22,23
High 7 11-15,18,21
By Key Question Key Question 1 6 10,11,13,17-19
Key Question 2 12 10-21
Key Question 3 6 10,12,13,18,19,21
Key Question 4 1 11
Key Question 6 3 11,22,23

RCT=randomized controlled trial; IV=intravenous
* One study contained two comparison groups. 11
**Risk of bias of one study differed by outcome. 12

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