The model announced her fourth pregnancy Friday on Snapchat, sharing an adorable image of four pairs of shoes lined up in order from biggest to smallest ... with numbered blocks.

Miranda says she and Evan are adding a boy to the brood ... and this will be their third child together.

She teased the baby news on her Instagram and directed fans to her Snapchat account on the platform her extremely wealthy husband owns ... and she's already got a little baby bump showing.

Miranda and Evan have two other sons from earlier in their marriage ... and she also has a son with Orlando Bloom from a previous relationship.

Now, Miranda's preparing to bring another boy into the world ... no wonder she's saying she's a #boymom.