BabyToday iPhone app

This was an iPhone app to do much the same as the baby birth probability on this webpage. It's not longer on iTunes (as I switched to Android and let my apple dev subscription lapse.) The source is here.

If you are expecting a baby, and it's getting close, then every day seems to start with wondering "Will it be today?". This page is about an iPhone app which will tell you the probability of it being today (or any other day).

Tell the app your due date, and today's probability will be calculated. The free version just tells you for today - the paid for (but cheap!) version will also tell you the probability for any other day (for when you are wondering how late you can still travel / go out / go to the football etc). It's an iPhone version of the baby birth probability on this website.

The due date is remembered from one run to the next.

It's far from perfect - see below for the source of information etc. Don't make plans based on this number - it's just a statistical view.

Calculation details

The number is based on UK National Health Service data of 640,000 births in 2005. There are a few likely errors in the whole calculation:

• It allows for the fact that your baby has not been born yet by telling you the percentage of the remaining births from today which happen on the selected day.
• There are different ways to calculate the start date of the pregnancy. I can think of an obvious one, but the standard basis is the first day of the Last Menstrual Period (LMP), about 2 weeks earlier. Midwives are directed by the survey to use the LMP data, but many probably use the (more accurate) date from an ultrascound scan.
• There are only weekly statistics available. I've interpolated daily figures on a sliding average basis - there is a small error in this approach
• Figures are only recorded up to the end of week 42
• No allowance is yet made for multiple births (generally born around 3 weeks earlier), Induced and Caesarean births or mothers race.
• Other factors such as mothers age, marital status, fathers occupation seem to have little impact on the stats