Jennifer Lopez's 'baby bump' stands out a mile on New York film set

Their twins have barely just turned one, but it looked as if another new arrival could be on the way for Jennifer Lopez and Marc Anthony this week – if the actress' midriff was anything to go by.

Closer inspection of J-Lo's burgeoning baby bump, however, revealed it to be fake. It was only part of her costume for her role as a pregnant woman in new movie The Back Up Plan, which she was busy filming in New York.

In the romantic comedy the brunette beauty plays Zoe, who becomes pregnant through IVF, only to meet her dream man – played by Australian actor Alex McLoughlin – on the same day.

It marks a return to the big screen for the actress – it's her first film role in three years after her last movie Bordertown went straight to DVD in the US. She has instead been concentrating on being a mum to twins Max and Emme.

There's a big event in store for Jennifer this week – she'll mark her 40th birthday on Friday. There's been no word on her feelings about hitting the landmark age, but it's thought Marc might have a surprise or two up his sleeve after she sprung a special Cuban-themed party on him for his 40th last September.