In the UK, giving birth tends not to be determined by vote. (Compared to e.g. the US, where "forced birthers" have voted for such legislation)
If "The UK should have net migration of at least 600k/year" was on the ballot, which way would you vote?
LOL at your use of "should". I'd vote "not giving a shit about migration figures"; if it's ranked-choice, that would be sandwiched above "why is this even a vote, let people live wherever they want" and below "more safe routes for migrants, less gloating about channel drownings".