I'm a little bit confused about what that is. If you are admitted to hospital for pregnancy and its not delivery (thats a different category that is far larger in absolute numbers) then something has gone wrong.
And herein lies the joys of medical coding :). Likely more than 235k normal pregnancy checkups happening in hospitals over 3 years in the UK, these "Z34" codes will likely get coded as admissions if someone is admitted for concerns around the pregnancy and the net result is everything with the pregnancy ended up fine. Maybe some other oddball scenarios I'm not thinking of too, but if you just go in for a planned pregnancy checkup and it comes out fine it (shouldn't) be coded as an admission just because it was done in a hospital location. Unless the NHS just has really odd coding practices, which is possible, but the other chart isn't drowning in 10s and 10s of millions of vaccinations of each type either.
For similar reasons you may find a ton of other things which aren't normally an admission in the data, but at numbers less than one might expect because that alone isn't usually reason to admit.
