OB Datum: Pregnancy Dating

Calculate and compare pregnancy dates with a clear explanation of every result.

OB Datum is a clinician-first pregnancy-dating workspace for iPhone and iPad. It performs deterministic calendar arithmetic and shows the source, formula, equivalent dates, and calculation-engine version for review.

CALCULATE FROM

• First day of the last menstrual period, with optional regular-cycle adjustment
• Documented conception or ovulation date
• An established estimated due date
• Gestational age documented on a known date
• IVF embryo-transfer date and documented embryo age

EVERY FEATURE INCLUDED

Every dating method, read-only Health import, full dating reconciliation, unlimited anonymous saved cases, formatted sharing, Calendar export, and custom timeline milestones are included in the downloaded app. There is no subscription, advertising, or separate feature purchase.

In Reconcile, keep an established EDD locked while comparing the dates implied by LMP, ultrasound gestational age, and IVF/ART. OB Datum reports signed calendar-day differences and never changes, averages, or recommends changing the established EDD.

EXPLORE THE TIMELINE

Calculate gestational age on a selected date, find the date corresponding to a gestational age, review descriptive milestones, and explore an interactive pregnancy wheel with accessible day and exact-date controls.

PRIVATE BY DESIGN

• No advertising or tracking
• No patient names, record numbers, contact details, or notes
• Anonymous saved calculations stay protected on your device
• Optional read-only import of the latest menstrual-cycle start from Health
• Calendar export includes only the EDD and no patient identifiers
• The widget opens OB Datum without displaying pregnancy or case data

OB Datum also provides a privacy-safe due-date action for Shortcuts and shareable calculation summaries.

OB Datum supports date arithmetic and clinical review. It does not diagnose, prescribe, select a delivery date, or replace professional judgment. Independently verify every input, result, and source before clinical use.