Contraction Timer 2.10.2
the author of this app says:
Contraction Timer takes the math out of labor by keeping track of contractions and doing all of the calculations automatically. It even provides audible and visual notification when contractions are three minutes apart or closer.
Contraction Timer keeps track of all of the data that a midwife or doctor finds most useful and lets you keep notes for anything else you want.
When you're done, you can even save the information to a memo pad for editing and printing.