OB Calc Pro: Designed by a doctor, for doctors!
OB Calc Pro is designed to quickly calculate a variety of medical test date windows based on 4 different methods used to estimate the Due Date of a pregnant patient. The Android version has up to 10 custom test names and dates while iOS has 5. Additional tests will be added to iOS soon.
The 4 methods are LMP, EDC, Sonogram and CRL (from Sonogram). The CRL method is currently only available for Android, but will be coming to iOS shortly.