Can I estimate this using population of country divided by average life expectancy..this would give number of avg births per year, then I can divide this by average number of children per woman (say 2) to get number of mothers?
Get Active in Our Amazing Community of Over 452,000 Peers!
Number of first time mothers - market sizing
Overview of answers
This is not a strong approach.
1. The major mistake is the following: you assume an average of children per woman, which is the same as assuming that EVERY woman will have 2 kids.
In real life, you have a good level of varuation. Zero kids, one kid, three kids, etc. Making an obvious exageration, you can have an average of 2 with 50% of the woman having 4 kids.
Therefore you should be considering woman with no kids, with 1 kid, or with 2+ kids.
2. I also don't like much the idea of dividing population by average life expectancy. At least not without stating a few relevant assumptions, as this assumes stable population for a long time, and this is only true if you assume that fertility rate has been close to 2.1 for a long time, or that any value below has been compensated by immigration).
This is critical because if you afterwards assume a value different than 2 or 2.1 for fertility rate, then you will have an internal inconsistency.
On a minor note, this also assumes that every person lives up to the stated life expectancy (this is the same mistake as on number one). While this is not a huge mistake in the developed world, it is significant enough that the recommendaed fertility rate to maintain population is 2.1 and not 2.0. So a 5% difference. Not a huge mistake, so I wouldn't be too concerned about this one.
Hope this helps in steering you towards the right direction.
Hmmm, that would not get you avg births per year as it ignores the population pryamid.
Either a) Segment the population by age and think through how many would have children in a given year or b) Reference population replacement rate (1.9) and figure out if that country is above or below that rate (based on it's economic development level and region)….then identify the # of births in a given year to keep that rate sustained.
Make sense?