A financial question about what to rent...

My husband and I have been looking for a 2 bedroom rental in Brooklyn in the hopes of starting a family soon, and wanting a place we can stay in for many years. But, with prices as amazingly low as they are right now, I'm suddenly wondering if it would make more financial sense for us to rent a 1 bedroom for 2 years (assuming we get pregnant immediately which obviously is no guarantee), we figure we can share a 1 bedroom with a baby until it's a year old- 1 bedrooms are significantly cheaper, so that would allow us to save a ton of money, and then move into our 2 bedroom in a couple of years (probably still a rental). My question is, what will most landlords do when the market rebounds in a year or two, assuming it does? Will they bump the rent right back up to market rate when the lease is up even if that means a sudden $500 - $800+ increase for their tenants, assuming the place isn't rent-stabilized? Or are they more likely to bump it up slowly over a number of years, raising it a little bit each time our lease is up? The reason I ask is that if they likely won't raise it steeply and suddenly when our first lease is getting renewed, maybe it would make more sense to find our 2 bedroom now and kind of lock ourselves in at a great rental rate and then not have to worry about the expense of moving later.

Any comments would be greatly appreciated! Thanks!