I don't know what the answer is tbh. I left work the day I had dd (12 weeks prem) as I hadn't worked there long enough to qualify for mat leave. I didn't return to work full time for 5 years.
During those 5 years I worked evenings and weekends with a lot of family support dd had so many hospital appointments/short hospital stays that holding down a 9-5 would have been impossible.
Dd attended nursery for the first time aged 2 and caught an infection that led to a month in hospital and 6 months bed rest, learning to walk again etc. Again that much time off work would have been impossible.
She's older now and still has 6-8 routine hospital appointments a year which require a full day of work (hospital is an hour drive each way and generally 2 hours in there) so still a big chunk of my leave.
Sorry for rambling.. I suppose my point is the repercussions of having a prem baby last years, and of course full term babies can have long term health issues too, so where would the line be drawn?