Cost of living, especially childcare costs.
Leaving it later to start a family (partially due to the above - saving for house, waiting until career is more advanced)
Also taking longer before being ready to settle down - difficulty with socialising during and post Covid, rise of online dating apps filled with ... less than honest men perhaps not as keen to settle down as profiles might suggest.
Widespread press coverage of issues with education system
Widespread press coverage of issues around accessing decent medical care - dentist, GP, and let's not forget the awful things coming out about maternity care in certain areas.
For some, concerns over the climate change - is it fair to bring children into this world? etc
General disillusionment with society.
But for most, sheer practicalities based around ££££££.