Cowell is expecting his first child with Silverman and the brunette beauty has begged him to at least reduce his 40-a-day habit when their baby arrives, reported Contactmusic.
"Lauren's demanding that Simon gives up smoking, or at least cuts down. She's already tried to ban him from smoking when he's with her and wants him to cut down on alcohol as well, in time for the baby's arrival," a source said.
However, a spokesperson for 'The X Factor USA' star insists he has no plans to give up his habit just yet.
"I had to go on a health kick because I have to balance smoking and drinking, which I do like. And then on the other side I exercise and then I have vitamin shots.
"Like last night for example, I had a litre of injections being poured into me through a drip and at the same time I was having a couple of vodka and sodas. So it kind of makes it bearable," he said.