The 38-year-old is expecting a baby with her husband Josh Kelley, but for her role as defence attorney Sadie Ellis she has to shoot a sex scene with her co-star Steven Pasquale.
As Heigl is in her third trimester, her swollen stomach is getting in the way of their lovemaking scene for the show, which will air from February onwards, reports femalefirst.co.uk.
“There’s just this basketball between us. I’m like, ‘I’m so sorry, so awkward!’ and he was lovely, but you don’t feel beautiful, really. It can get a little steamy, but with this situation it can’t get that steamy,” Heigl told Extra magazine.
Heigl, who is already a mother of two adopted children Naleigh, 7, and Adelaide, 4, has enjoyed every aspect of her pregnancy, although she is shocked by how big her bottom has gotten.