"Can't wait to meet this little one", the Eastenders actress captioned the picture, with fans eagerly adding their comments of support.
Jacqueline and her partner The Only Way Is Essex star Dan Osborne revealed they were expecting their first child together in August, releasing a joint statement saying that they were "thrilled by our news".
The 23-year-old TOWIE star - who welcomed son Teddy in December with ex-girlfriend Megan Tomlin - added, "Becoming a father has been the most thing to ever happen to me. I can't believe I'm going to be a dad again – I'm truly blessed."
A spokesperson for EastEnders also offered their congratulations to Jacqueline, adding: "Everyone at EastEnders is thrilled for Jacqueline," said the rep.
In October the the two hosted a celebratory party to mark finding out the gender of their first child.
Pictured next to the scan was the couple's 'baby reveal cake', a popular style of cake offered at baby showers where the sponge inside is dyed blue or pink to indicate whether the baby is a boy or a girl.
While the parents-to-be posed for a picture with a slice of the cake, which was iced with the phrase "twinkle, twinkle little star... how we wonder what you are?", they kept their fans guessing about the sex of their baby by filtering the picture black and white.