The 54-year-old music mogul and 36-year-old Lauren were walking in Beverly Hills when Simon was captured with his crafty fag - just weeks after vowing to give up.
US chat show host Arsenio Hall recently told the dad-to-be that he could smell smoke on him, and instructed him to 'stop smoking for the kid, man'.
Simon promised: "I'll stop. Yeah, I'll try."
Last night anti-smoking group QUIT branded those who smoke near pregnant woman 'selfish' and warned of the risks to mother and child.
Spokesman Glyn McIntosh said: "Secondhand tobacco smoke is a mixture of at least 4,000 chemical compounds, dozens of which are known or suspected reproductive toxins.
"Women exposed to other people's tobacco smoke during pregnancy are more likely to have premature births, lower weight babies and some research shows it can result in the loss of the baby.
"It's selfish to smoke near someone who is pregnant."
Tut tut Simon!