Should i tell them already?

So im 31 weeks pregnant and my husband and i have been keeping it quiet all these months the only people who know are his cousin and his cousin's sisters. And from mu family only my aunt and my dad's family knows. Thus is our 4th and last child. We kept it quiet because we didnt want to hear the negative comments and whatnot. But we're still deciding whether its time to come out with it already. I mean they have to find out some day anyways.