Blake was attending the 10th Annual Forbes Power Women’s Summit Thursday in NYC … she entered the event and posed for pics, proudly showing off the upcoming addition to the fam.
Witnesses at the event tell TMZ … employees only let a few photogs shoot Blake — telling them beforehand that this would be a "sensitive shoot," adding they’d know why when she walks down the red carpet.
Boy, were they right! Blake’s noticeably pregnant, but it’s unclear how far along she is.
Blake posted a swimsuit pic a few weeks ago — though we don’t know when it was taken — and there was no bump in sight … possibly intended to throw people off before the big reveal.
Blake and Ryan have 3 kids together already — 7-year-old James, 5-year-old Inez, and 2-year-old Betty.