Kate Mara and Jamie Bell welcome first child together

The celebrity couple have been married for four years

(Getty Images)

Kate Mara and Jamie Bell have announced the birth of their first child together.

The notoriously private acting duo welcomed a baby girl a “couple weeks ago”, according to Mara’s Instagram post on Monday, which shows a photograph of the newborn’s feet on top of a fluffy cream blanket.

The snap has already garnered more than 30,000 likes, including one from actor Amy Schumer, who gave birth to her first child earlier this month.

Friends star Courteney Cox commented “Awwww so sweet! Congratulations you too!!” underneath the photo while Jessica Chastain added: “Congrats dear one!!!”.

Mara and Bell’s baby, whose name has not yet been revealed, will be the second for Bell, who shares a five-year-old son with ex-wife Evan Rachel Wood.

Mara and Bell starred together in the 2015 superhero flick Fantastic Four, a project that fans have credited for fuelling their romance, though they met roughly a decade previously.

“We didn’t meet on Fantastic Four,” Mara revealed on Watch What Happens Live with Andy Cohn in 2017.

“We met like 10 years before. We did a screen test together and we had to kiss and it was very – I had to kiss many guys that day for the screen test.”

Mara added that she and Bell “fell in love” while promoting Fantastic Four.

The couple married in Los Angeles in July 2017.