There is precedent already for sterilisation: https://www.itv.com/news/2015-02-04/judge-rules-woman-with-learning-disabilities-can-be-sterilised#
An IQ of 70 is learning DISABILITY territory.
As a previous person said upthread - this will range from needing 24hr care and can’t be left un-supervised, through to being able to live independently, have a minimum wage type job (stacking shelves etc), able to do food shopping, able to get by with the help
of family/friends/carers who would help
with life admin, managing finances etc.
And everyone in between those two ends.
For people at the more severely impacted end, these people are routinely placed on some method on contraception - either pill, or injection usefully as least invasive - as they do not have the capacity to consent to sex, do not understand that sex leads to pregnancy etc. It is a legal decision taken in the persons ‘best interest’.
For those at the less impacted end, they are still vulnerable, but they may have capacity to consent to sex, may understand that sex leads to pregnancy etc. Therefore contraception is by their choice and consent.
But just because you can consent to sex, and may even want a baby, does not mean that you can care for one.
I used to work with adults with learning disabilities. We had a couple who attended our service, they’d been together for years. Both lived in 24hr care, but they their capacity to consent to sex differed. Female did have capacity and male didn’t. The lady used to talk a lot about she’d like to have a baby with her boyfriend. There would have been no way at all that would have happened. They would have forgotten to feed it after an hour, forgot it existed and left it somewhere, anything could and would have happened as they would not have been capable at all. So she was on birth control, which was a best interest decision and it would have caused her trauma to birth a baby and then have it removed, than to just not have a baby.