Only a few weeks into filming the David Cronenberg project “Eastern Promises”, Naomi Watts discovered that she was pregnant. By the time she found out, she’d already performed a few stunts, such as riding through busy traffic on a motorcycle. Had she known about her brand new baby boy, she probably would have left it to a stunt double.
This turned out to be a funny coincidence for Watts – her character in the film is a midwife, and the actress did extensive research on birthing, pregnancies, and fetal development, only to find out she’d be getting a first-hand experience at the same time.
Halle Berry — X-Men: Days of Future Past
Just before filming "X-Men: Days of Future Past", Halle Berry discovered she was three months pregnant. Three months isn't too bad to keep a baby bump hidden, but Halle Berry's character, Storm, is most often seen in skintight leather.
The producers very quickly scheduled her scenes as early as possible to get her in before her bump grew too large. Even then, Berry noted that it didn't take too much for the outfit to constrict her midsection. They were done in the nick of time. Unfortunately, the movie somewhat suffered from this – every shot with Storm in it seemed a little disconnected from the others.
Angela Kinsey — The Office
Kinsey played another Angela – Martin – on the American version of "The Office". She had a little life growing inside her while filming season four. The producers thought about having her character get pregnant as well, but decided against it.
Thankfully, it didn't prove too difficult to conceal Kinsey's pregnancy during filming. She's so short compared to most of the other cast members, that filming her from the shoulders-up happened naturally. Plus, the office setting made it easy to stick her behind a desk and call it good. Even the mockumentary testimonials are filmed with the face in the center frame and zoomed in, so really there was little she couldn't do.
Angelina Jolie — The Changeling
Jolie has been showing off her acting skills for decades, so it's no surprise she's had at least one project during a pregnancy. She starred in Clint Eastwood's film "The Changeling", where she played a mother whose son disappears. Her own pregnancy may have increased the emotion of her intense performance, though she only found out she was pregnant at the tail end of the shooting.
She didn't even make it public until filming was over, and being so early in development meant she didn't require any extra cover for her character. Jolie ended up with twins and was fine with it – filming a movie about a character losing a son made her want more children.
Marcia Cross — Desperate Housewives
For the show "Desperate Housewives", Marcia Cross played Bree Van de Kamp. During the third season, this actress found herself pregnant, and with twins. Even early in pre-birth development, twins make a bump appear much larger and earlier than a single child. And so, the show piled on the big clothes, dark colors, and big props.
Eventually, her doctor told her she needed bed rest, so the show took a long day filming everything they needed from her in one day. After that, she took a long leave, disappearing from the show for the rest of the season and letting the other characters do their thing.