Watts, who turned 48, shared a throwback photo on Instagram of herself in a pram.
"Another birthday!! #eek But I think I'm younger than this #vintagestroller?? Not quite sure what's happening here... #eek #70's #photoop #oldschool #raisedbyartists," she captioned the picture.
"Happy Birthday Sweetheart," Schreiber commented on the post.
The Oscar-nominated actress celebrated her birthday in New York City, where she is been busy filming "Gypsy".
The couple of 11 years announced their decision to split via a statement on September 26. The duo, who never married, are the parents of sons- Alexander "Sasha" and Samuel.