That was me!
I have an online business, which was still relatively young when I fell pregnant. I hired my first employee when I was 8 months pregnant (started the recruitment process much earlier on though, obvs), and also created a new office space to separate the business from home. It was a big step into the unknown, and I was pretty stressed about it before it fell into place. But, it worked out very well. My employee is still with me, and I am able to work mostly flexibly around my little girl, who is now nearly 4.
I'm now TTC number 2 (no joy so far, but that's another thread), and so am hoping that, all being well, that there will be further transition in the future. So, I'm now at a place where I'm building systems and processes to remove me from being the central cog, in anticipation.
I felt really well during my pregnancy - fortunately - and I kept my hand in during my maternity leave, increasing my hours over time to now where I'm full time again, albeit not working 9-5. Mine's a business that I can keep at more of an arm's length though, compared with a freelancer type situation. I think this is a key difference with my situation and MrsMargoLeadbetter's. Did a lot of quick bits of emails during naps/when DD was in sling, emailing from phone during BF sessions, etc. etc. etc. ANYTHING to fit in a bit more work!
So, in short, for me, it was entirely doable as I had help and because of my type of business. Also, I'm a worker type/ideas-y person anyway... I like to feel productive and feel like I'm moving forward... and so the business was a bit of a sanity saver at times in the midsts of babyhood!
I spent a lot of time in my pregnancy working out all the pros and cons, costs etc. of all the different approaches to managing it all. And, you know, things also change over time, e.g. childcare needs, what you need support with domestically and on the business front.
Last of all, if you have a ltd company, you can continue to take dividends during mat leave.