Obstetricians, are you tired of calculating important patient dates using a calendar or spreadsheet? While similar to a pregnancy wheel, OB Calc Pro is specifically designed by an obstetrician, for obstetricians. Finally obstetricians have an efficient and simple method to calculate the important test date windows for patients.

(Appreciation to Dr. Rosanne Botha, an amazing OB/GYN, for the inspiration behind this app.)


• Last Menstrual Period (LMP)
• Expected Delivery Date (EDC)
• Sonogram Date and Fetal Age (Sonogram)
• Crown Rump Length (CRL)


8 common test dates are set up by default. However, these test names and date windows can be completely customized in the Settings screen so you can set up your own items if you prefer. OB Calc Pro supports up to 10 test dates.

If you like this app, please consider leaving rating comments as well as emailing me directly with feedback. You can reach the developer directly at

** Disclaimer
Remember to test out the app on your specific device to ensure calculations are verified to your expectation.

What’s New

Version 1.05.03

• Updated the data tables for the CRL calculation.

Ratings and Reviews

storksaid ,

Can't work without it

Usually it's spot on so if I forget my phone at home and don't have it to wheel out my patients I feel totally lost. This is an especially great tool for those of us who need reading glasses to see those tiny wheels.
Highly recommend it and have had several of my coworkers download it for the same reason

Developer Response ,

So glad to hear you find the app useful. Thanks for spreading the word to your coworkers.

ZZB 1 ,

Great app for calculating NT & FIS testing date ranges

Great straightforward app and at a great price. Responsive developer.
Let's me calculate all the testing date ranges for the first and second trimester prenatal aneuploidy screening tests.


Glen Botha
16 MB
Requires iOS 9.0 or later. Compatible with iPhone, iPad, and iPod touch.
English, French, German, Portuguese, Spanish
Age Rating
Rated 4+
© 2011 Glen Botha


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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