Smoking Pregnant

Not actually about me, but my sister-in-law. 6 months pregnant with baby #2. She smoked like a freight train all the way through her first pregnancy, and baby was born with no issues (although he was about a month premature).

With baby #2, she’s cut down to only about four cigarettes a day (she used to smoke a pack and a half). We’re all really happy with how much she’s cut down, but it still makes me nervous.

So, question - YES I KNOW WHAT ALL THE STUDIES SAY, but in your/your family’s PERSONAL experience(s), did smoking affect birth weight/prematurity/defects/etc?

Thanks!