S.E.S actually had a chance to come back through MBC's 'Infinity Challenge' like Sechskies did. However, because of Eugene's pregnancy, the ladies couldn't come back until now. (On 'Infinity Challenge', Girls' Generation's Seohyun took her place.) 

In an interview that the trio had with 'Section TV', Bada joked, "She planned that pregnancy for S.E.S' 20th anniversary," explaining that they were actually able to come back on their 20th anniversary instead.

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Eugene said, "It's actually a relief that I couldn't go back then. This became a chance that could fill up that disappointment."