Everything you see is a button! Touch any of the light blue boxes to bring up the date selection calendar. You can calculate the dates and the gestational age using any date along the pregnancy as a reference point. For example, selecting EDD will allow you to enter an Estimated Due Date, and the app will calculate the rest of the dates according to the date you entered. Selecting Conception will allow you to enter a date for the approximate date of conception, and the other dates will be calculated relative to this date. The calculated data will appear in the light blue text boxes in the right hand column.
You can also touch/click & drag along the boxes to smoothly scroll through the dates. Try it out! Abbreviations: LMP = Last Menstrual Period (use first day of period); EGA = Estimated Gestational Age; EDD = Estimated Due Date

• Touch/click any square to select that date
• Touch/click anywhere outside the floating calendar to cancel

Month selection:

• The double arrow buttons change the year
• The single arrow buttons change the month
• Touch the month name to bring up the month selection grid. Month can be selected directly

Direct date entry:

• Touch the calendar heading ("Estimated Due Date" in the example image) to bring up a text input box.
• Date can be entered in almost any format.

• touch/click and drag on the light blue date input boxes to scroll through dates
• [IMG]

To enter weeks and days for the gestational age:

• Touch EGA weeks input area to input weeks
• The cursor will automatically move to days input box if weeks value has 2 digits
• Days input box takes only one digit
• The dates will be calculated accordingly.

• Reset
• Delivery date
• Save
• Copy/share
• Patient list

This is the feature that sets this app apart from all others!
It answers the questions: What would the gestational age be at ___ date? and When will the patient be __ weeks gestational age?

• Touch the "TimeMachine" text to set the date; this will calculate the gestational age for any given date.
• Touch the weeks/days input boxes to enter a gestational age; this will calculate the date for a given gestational age.
• Using TimeMachine does not affect any of the other rows or the base data.
• TimeMachine calculation and directionality will remain even if primary calculation is changed
• eg - Select TM date to determine gestational age at that date. Change main calculation by entering new LMP/EDD/EGA/etc. TM row will still show the previously selected date with the corresponding new GA.
• If GA is entered for the TimeMachine, changing the main calculation will retain the TM GA and show the resulting TM date calculation.
• TimeMachine will reset if the calculator is manually reset, or a mode tab is selected (US/IVF/CRL)

The buttons at the top of the app will toggle the display of the alternate calculation methods including Ultrasound gestational age, IVF embryo implantation date, and Crown-Rump Length calculations. The ultrasound option is useful if you know what the gestational age was on a specific date (eg, ultrasound examination date). Enter the information as desired, and the app will calculate the dates accordingly. The information line at the bottom of the tab will also update to show ACOG's recommendations on when to use the ultrasound gestational age instead of LMP.

• enter embryo transfer date
• cursor auto advances to embryo age input - one digit only

The IVF panel allows gestational age calcuation based on embryo age (days) and implantation date.

• enter date of CRL measurement (ultrasound)
• enter crown-rump measurement
• formulas are only validated up to 84 mm
• touch preferred formula to use that gestational age
• reference link for the selected formula will appear below the list

The CRL panel calculates the gestational age estimate based on crown-rump length measurement of a first trimester embryo. There is not one "standard" formula, so the calculator displays results based on a number of formulas. Each of the calculated gestational ages can be used as a point of calculation. Here are the formulas and referenced articles (Equations give EGA as results):

• Sahota et al: \(26.643 + 7.822 \sqrt{crl}\)
• Robinson & Fleming: \(23.73 + 8.052 * \sqrt{1.037 crl}\)
  [Formula obtained from systematic review article by Napolitano et al]
• Verburg et al: \(7 e^{1.4653 + 0.001737 crl + 0.2313 \log{crl} }\)
  (original formula gave GA in weeks)
• INTERGROWTH-21: \(40.9041 + 3.21585 \sqrt{crl} + 0.348956 crl\) https://intergrowth21.tghn.org
• Drumm et al: \({{0.374 + \sqrt{0.374^2 + 0.048 crl}} \over 0.024} \)
• Napolitano et al: Systematic review article, lists various formulas

• enter free text to be saved as "patient information"

• drag slider to adjust menstrual cycle length
• (if accurate cycle length is not known, use the default 28 days)
• touch "Cycle Length" label to reset to default