Hi across!
Your post really resonated with me as well. I just turned 33 and I'm in the 4th year of a part time PhD (I work at a university full time). I was once in your position and I chose to stay on birth control until I finished my PhD (still not finished but am considering coming off the pill!). I suppose the things that I'd be thinking about are very practical.
Would the PhD be part of the job you're in now (similar to my current position - I'm working full time and the PhD is just sort of a 'perk' that I'm expected to do in my own time- i.e. nights and weekends) or once you get the funding would you become a full blown student? If you have to work and do the PhD in your spare time, I'd say that would be very difficult to do with a new baby. I'm sure people have managed it before, but if you can avoid doing both, I say avoid doing both. I chose to delay starting a family, but on the plus side, I'm getting paid a salary to do a PhD that would have cost me a lot otherwise.
If you are going to become a full blown student where you get paid through funding (i.e. a stipend), and all you had to do was the PhD (ha! 'all you had to do'), it will also be difficult, but definitely doable. A friend of mine took a year off to have her little one and she is doing well. She came back part time and it is sometimes difficult for her to get back into her work only working a couple of days a week. Although it works well for her becuase doing a PhD is so flexible and she can work from home or when the baby (who is now 4) is sleeping etc. I suppose it might be different in a lab setting. The downside is she doesn't get the full council tax reduction (and other perks) that a full time student would, and it will take her a lot longer to finish. After 4 years of my PhD I'm sick of the sight of it so that might be something to consider!
If you stay in your current job without taking on the PhD, you'd have the maternity benefits, which I'm assuming are pretty good at Oxford. If you become a full-time (or part-time) student, you might not get paid if you're on maternity leave. I think my friend just didn't get funding while she was on her year off. Then again, she had the flexibility to take an entire year off and come back when she was ready - so that's something to consider too. For me, your best situation would be to get pregnant now while working full time in your job, make the most of the maternity benefits, then when you return become a full time student and do your PhD!
I am probably 3 months away from submitting my PhD and I'm tempted to go off the pill to see what happens. I'm assuming it would take a few months to get pregnant anyway and it takes 9 months to have a baby, so this PhD better be finished by the time a baby arrives! The problem for me is that we were hoping DH's job would transfer him to Canada, which we thought was going to hapen but is still up in the air. Failing that plan, we were planning on moving back to the USA. Of course, with no jobs in place that would be difficult given the healthcare situation, especially if I was pregnant! So if I did get pregnant in the near future, that would mean staying in the UK for longer. I've been here nearly 8 years and am really starting to want to go home! Not to mention the families- his will be devastated if we had a baby here and then moved away shortly after it was born, mine will be sad if I have a baby here and they can't come see it. I know, no win situation so we just have to do what is right for us. Practically, having a baby in the UK makes sense but I'm scared I'll be really sad/psychotic about not having my family around and that we'll end up staying forever instead of moving!! But then my biological clock keeps ticking and all of that. . . AHH!!!
I know. Overthinking it. probably a displacement activity instead of focusing on the PhD that is almost done. But it is really difficult!
Across, good luck with your decision/whatever happens. I know it will all work out- these things always do! Keep us posted! xxx