May depend on what you are studying and the result you are hoping for.
University can be intense. I, as well as all my friends and classmates, were studying and working insane hours. In my final year I worked every day for six months until my exams were finished, I was up to studying 20 hours per day by the end and even missing nights sleep! Everyone was sleeping around three hours a night.
That was a particularly intense course in a difficult subject and at a challenging university. However that's what we needed to do. In the previous years, out all day at university for classes and then five or six hours in the evening for study, homework and preparing for tests was normal. There is a long summer break, four months, but the rest of the year would have been impossible with children. Winter holidays are for studying and preparing for January exams and/or assignments due after the holidays. Yes they are that cruel!
Most universities give you a deadline number of years to graduate, so you can take at least a year off, maybe two or three. The problem with more than a year off is that you forget all the things you've been studying and learning. Again depends on the subject, but most build upon what you've learned previously, class after class.
Would you be paying fees? They are quite high in some places, that would be a consideration as universities don't return these if you leave. A yearly fee is plenty to freeze eggs or embryos, but of course it's not as simple as bamn do that and it'll work when you choose, I know that. Back up really, or fertility preservation.
Don't worry about messing the university around. They charge you are fortune and students are changing courses all the time.
Are you studying to go back to a career? What about starting a new job with two young children, is that something you want?
I did another degree at about the same age, but I had been through the university system before and was going back to an undergraduate level start when I'd already gone through to the end of postgraduate in another field plus a few years of life, reading good books, following the news and in general thinking gives maturity to intellect, so it was a bit easier in terms of the course content. However I did find that 18 year olds just out of high school were much more comfortable than me fitting into university work demands, because it was just a continuation of school for them and they didn't have any other grown up responsibilities to deal with. I found it overwhelming from day one, there just weren't enough hours in the day and I worried constantly about not doing my best work because I was also running a home that wasn't university/parent managed and being an adult with a life! I did it in the end by working with the american system, which is much more flexible, but I didn't have a baby during that time!
I think honestly you should think about how you feel about having another child. If it's something you really want to do, I'd start trying now. If it's well that would be nice but fine if it doesn't happen, maybe wait a bit as you're still fine with your age even after uni. You can also go to university and study whilst pregnant, the university will be helpful and accommodating, so if you fell pregnant later this year and just made sure you had enough time to get through the first year without popping (and you expect a comfortable pregnancy) you could get a year out of the way and the take a year out. You may not want to go back, but you'll know how you feel!
Good luck!