Nobody remembers people that come to open house.  Imagine all the people that come, they won't remember your name even if you introduced yourself.  Especially if you're applying 3-4 months later to reach the school's deadline for admissions.  They'll only look at your portfolio etc...etc..  If you get admitted that'll be next year which by then you would have already given birth.  

I don't think it's that big of an issue to begin with anyways - nobody is going to ask you to explain your pregnancy (it's open house all they care about is painting themselves in good and prestigious light, just like you, to be able to get your tuition money).  If that's what you're worried about, it's much ado about nothing.  Nobody would remember anyways, come application time, and potentially come the start of school the following year.  

Thanks choresi, that is reassuring.

You don't have to explain anything. Dont bring it up yourself. Congrats by the way.

Not a lady architect, hope you don't mind. They will not care that you're pregnant, all they see is a potential tuition payer, so no explanations necessary. It's your "problem" how to manage studying with family life and when you think you can handle it and are paying your tuition, they couldn't care less is my guess. Also, what's there to explain do you want to prepare diagrams of how it happened ;) Good luck, congrats and enjoy.

I don't think they care at most places. I had people in my undergrad and grad studios who all had families, and no one batted an eye. It's about the work. 

Good luck to you and congratulations on your new baby!

yes I've thought about how that will add another layer of difficulty to an already difficult first year

if you think you've thought this through and still decided it's a good idea, either your decision-making is questionable or you don't actually know what that first year is going to be like. 

you won't be able to do both things well at the same time. your professors will expect you be in studio for far more extended hours than a newborn will allow, and they will not give a shit that you have a kid when it comes to giving you feedback/critique. especially at first, the work is incredibly time-intensive; the quantity of time you spend working on your projects will have a nearly direct relationship with the quality of the end results. 

in other words, if you are good at being a new mom, you'll be terrible at being a new architecture student, and vice-versa. and if you're going to put yourself through the stress and expense of a graduate program, why do it when you can't possibly do your best work?

Some schools may do things differently, but at the open houses with which I'm familiar it's unlikely you'll even have any one-on-one time with anybody on the admissions committee.  Fall open houses are large, crowded events - it's mostly a lot of mingling - similar to what you'd experience at a gallery opening or something like that.  I doubt anybody you meet there will be able to attach your name to your face by the time you submit an application.

There was a new mom in a class I taught a few years ago and she seemed to manage fine academically but had panic attacks when field trips, site visits, or crits ran later than anticipated. At least once the baby ended up delivered to the police station by his daycare center. Faculty and classmates didn't appreciate the baby's visits to the studio. Building security confiscated her stroller (none allowed in university buildings) and let it get stolen. If you have a family member with a very flexible schedule who can be on call to collect the baby whenever you can't, and if you have enough hours of childcare every day and night that the baby never has to be at school then go for it. If not then don't.