Should I tell the Bride?

MWM0903

I am in a wedding this weekend and I am debating on whether or not I should inform the bride of my baby! This wedding is all DIY from the flowers, to the decorating to the reception. Being the Matron of Honor I am expected to help do everything and I want to help. Although, I know in my heart if I push myself prepping for the wedding today then tomorrow I will be useless. I would much rather give me all tomorrow and have Sunday to rest then feeling like I am going to faint all day tomorrow. I really don't want to tell her but I feel it may be necessary. Any idea's on how I can still help but not actually do as much?