There is a very common statement that across GB, an estimated one in three women will have an abortion (at least one) by the age of 45. I want to explore this and consider three points:
- How is this rate estimated?
- What are the key assumptions in the estimation?
- So what?
From my workings below, and because only a pregnant woman can have an abortion, I think it would be better to say:
One in six women who become pregnant will have at least one abortion in their lifetime.
The DHSC reports that in 2018 there were a total of 200,608 abortions for residents in England and Wales. It reports an abortion rate of 17.4 per 1,000 resident women of reproductive age (WRA) and that 39% of women who had an abortion had one or more previous abortions (78,237). Summary report here. (PDF)
From this we can derive that there are ~11,500,000 WRA. The age range used when counting WRA is from 15 to 45, so a total number of 30 years.
In 2018, 122,371 women resident in England and Wales had their first abortion. Extrapolating this for 30 years for all WRA, we get:
(122,371 x 30) / 11,500,000 = 1/3 (one-in-three).
I suppose the key assumption which I want to challenge, is that all WRA will at some point become pregnant and perhaps consider the choice of abortion. What if we recalculate this estimation based on the numbers of women becoming pregnant? After all, only pregnant women can have an abortion.
The Office for National Statistics (ONS), reports that in 2018, there were 839,043 conceptions to women in England and Wales. Link here.
Let’s first exclude those women who have already chosen to have an abortion for an earlier pregnancy, which in 2018 is a reported 78,237.
That leaves us with 760,806 women who became pregnant in 2018 and who had never before chosen an abortion.
In 2018, 122,371 women choose an abortion for the first time.
The calculation is:
122,371 / 760,806 = 0.16
An estimated one in six women who become pregnant, will have at least one abortion in their lifetime.