Pregnant Jessica Alba having her first son

Pregnant actress Jessica Alba is expecting a little brother for her two daughters.

The Fantastic Four beauty and her husband, producer Cash Warren, shared the gender of their third child in a sweet Instagram post on Wednesday (25Oct17), when Jessica uploaded a video clip of herself beaming with her arms outstretched as blue balloons and streamers fell from a box which appeared to be suspended from a tree. Her girls Honor, nine, and Haven, six, also joined in the fun.

"@cash_warren and I couldn't be more thrilled to announce...," the star began her caption, before adding a baby emoji with blue lips and an emoji of a blue heart, indicating they are having a boy.

She then confirmed the sex by adding the hashtags, "#officiallyoutnumbered #babyboy #cantwaittospoilhim #hugsandkissesforlife #soontobemamaofthree (sic)".

Jessica and Cash announced they were expanding their family in July (17).

The actress and entrepreneur publicized the news by posting footage of herself and her daughters holding balloons numbered one, two, and three on Instagram.

"@cash_warren and I are officially going to be outnumbered #babyonboard #herewegoagain #blessed," she wrote beside the snap.

The parents-to-be have already been trying to come up with suitable names for their third child, after deciding to continue their tradition of picking unusual monikers which also begin with 'H'.

"So my husband's name is Cash, that's his actual real name on the birth certificate," Jessica said during an August (17) appearance on The Tonight Show Starring Jimmy Fallon. "So our kids had to have unusual names that also were words. For some reason, we chose 'H'. It has to be single or double syllable, has to be an 'H', and it also has to be a word."

The couple wed in 2008.