Table 3.

Assessment of risk of bias of each study

^aMore than 10% of missing data

^bCOH protocol is different in both groups. And frozen-thawed embryo transfers were done in LPS group while fresh embryo transfer were done in eFPS group

^cMost known important variables are balanced

^dIt is unclear if some known important variables are balanced or not

^eBoth intervention and comparator were performed on the same group of women within a 12-month period. Therefore, variables are balanced

^fCOH protocol is different in both groups

^gWomen’s age was different in both groups. Only unsuccessful cycles in the eFPS cycles were included

^hIt is unclear if some known important variables are balanced or not

ⁱCOH protocol is different in both groups. Besides, denominator are cycles and not women

^jCOH protocol is different in both groups and participants in eFPS group are younger