MILWAUKEE (CBS 58) -- A new campaign is highlighting the impact tobacco and secondhand smoke can have on premature births and infant deaths.

The city launched a new phase of its "Strong Baby Campaign" on Friday. It encourages families to make their homes smoke free so their babies can lead healthier lives.

A study found a third of deaths were linked to tobacco use during pregnancy and exposure to secondhand smoke was a factor in 71% of sleep-related infant deaths.

"It's not just the mother, it's the grandmother, the aunts, it's the uncles. If there's a pregnant woman in your home, do them a big favor and take your cigarettes outside," said Mayor Tom Barrett.

The Strong Baby campaign will have messages posted at transit shelters, social media, and directly to families through programs and outreach efforts.