Forest plot of the relative risk of pregnancy loss comparing LMWH vs no LMWH. (A) All trials are included. (B) Multicenter trials only are included. “Favor LMWH” suggests a benefit of LMWH in preventing pregnancy loss; “Favor Control” suggests a benefit of no LMWH in preventing pregnancy loss; * denotes an indeterminate RR because there were no pregnancy losses among the 23 women from the HAPPY trial.²⁴