Table 2.

Randomized controlled trials (RCTs) of intravenous immunoglobulin (IVIg) in women with unexplained recurrent pregnancy loss (RPL).

Authors (years)	The number of previous miscarriages	Primary/secondary RPL	The number of experimental group/control group	Placebo	Timing of IVIg treatment	Success rates (experimental group vs. control group)	Conclusions
NA (1994) [33]	Three or more	Primary	27/30	5% albumin	5-8 weeks	74% vs. 70% (P > 0.05)	The effect of IVIg in primary RPL could not be confirmed.
Christiansen (1995) [34]	Three or more	Secondary	34 total	1.5% albumin	After pregnancy was confirmed	52.9% vs. 29.4% (P > 0.05)	The effect of IVIg in secondary RPL was uncertain.
Coulam (1995) [37]	Two or more	Primary (n = 56) and secondary (n = 49)	47/48	0.5% albumin	500 mg/kg/month before conception	62% vs. 38% (P < 0.05)	IVIg was effective for RPL patients.
Perino (1997) [36]	Three or more	NA	22/24	5% albumin	25 g/day from 5-7 weeks	68% vs. 79% (P > 0.05)	IVIg cannot facilitate the progression of pregnancy.
Stephenson (1998) [35]	Two or more	Primary and secondary	32/30	Saline	500 mg/kg before conception	70% vs. 55% for secondary RPL	IVIg seemed to be effective for secondary RPL patients.
Jablonowska (1999)	Three or more	Primary and secondary	22/19	Saline	20 g every 3 weeks after	77% vs. 79% (P > 0.05)	There is no statistically
[55].					Heart beat was seen by ultrasound		Significant difference between IVIg and placebo.
Christiansen (2002) [27]	Four or more	Primary and secondary	29/29	1.5% albumin	800-1000 mg/kg when pregnancy test was positive	58% vs. 24% (P < 0.05)	IVIg may improve pregnancy outcome for secondary RPL.
Stephenson (2010) [29]	Three or more	Secondary	29/39	Saline	500 mg/kg preconception	70% vs. 63% (P > 0.05)	No treatment benefit was found.
Christiansen (2015) [30]	Four or more	Secondary	42/40	5% albumin	400 mg/kg when pregnancy test was positive	54.8% vs. 50% (P > 0.05)	IVIg did not enhance the live birth rate in secondary RPL patients.

NA: nonanalyzed.