Women with unexplained recurrent pregnancy loss (n= 99).
High dose of intravenous immunoglobulin (IVIG), (n= 50).
Placebo (physiological saline), (n= 49).
The ongoing pregnancy rate at 22 weeks of gestation (31/50 [62·0%] vs. 17/49 [34·7%]; and the live birth rate (29/50 [58·0%] vs. 17/49 [34·7%] in the IVIG group were higher than those in the placebo group. The ongoing pregnancy rate at 22 weeks of gestation and the live birth rate significantly increased in women who received IVIG at 4-5 weeks of gestation as compared with placebo, but these increases were not evident in women who received IVIG at 6 weeks of gestation. Four newborns in the IVIG group and none in the placebo group had congenital anomalies.