Jennifer Garner was "emotional" about going back to work so soon after giving birth.
The 41-year-old actress - who has children Violet, eight, Seraphina, five and 23 month old Samuel with her husband Ben Affleck - found it tough starring in Oscar-nominated drama 'Dallas Buyers Club' while she was still nursing her young son, and was anxious about having to keep people waiting on set so she could feed him.
She told Radio Times magazine: "I was very nervous - it's hard to leave your baby at home and go to work. And I was a nursing mum, so I was extra emotional about it. By, by the end, it made me remember how much I like my job and that I have to keep things more in balance.
"I've nursed each of my babies and I've worked during that first year of having them. So, if we talk brass tacks here, that means I've had to work with a pump and feed the baby at lunch. I'm versed in how to say, 'In about ten minutes I'm going to need to disappear', but on this movie we moved so quickly, there was never time.
"So everyone had to sit and wait for me, which made it emotional because I hated making a crew wait, but I couldn't start weaning my baby just because of a movie."
The '13 Going on 30' star admits her children only have a basic understanding of what their parents' careers involve because they're too young.
Jennifer said: "They've always had some kind of sense of it. My daughter turned two while I was doing a play in New York, and if you asked her what I did she'd say, 'She has her hair and make-up done and takes bows on stage.' That's because I'd put her down for a nap during matinees and she'd wake up just in time for curtain call."