The Arizona Department of Health Services is partnering with the March of Dimes for a new advertising campaign urging expectant mothers to let nature take its course.

The campaign, with the theme "Healthy Babies are worth the wait," aims to reduce the state's pre-term birth rate by eight percent, from 12.7% of births to 11.7% of births, by 2014.

Terri Spitz of the March of Dimes says too many moms schedule their delivery – for example, to match up with a date that has meaning to the family, or for grandparents to be in town – rather than simply waiting until they go into labor naturally.

The ideal delivery date is after at least 39 weeks of development, Spitz says, adding that the later a baby is born, the healthier it's likely to be.

In fact, Dr. B.J. Johnson of the Arizona Perinatal Trust says the brain at 39-40 weeks of development is 50% larger than at 35 weeks.

He says nearly all hospitals that are part of his organization have pledged to wait until a baby is at 39 weeks of development to induce labor unless an earlier labor is medically indicated.  The biggest complicating factor, he says, is getting doctors to resist the pressure from their patients.

The campaign will also focus on making sure the mother is healthy enough to get pregnant and have a baby.  The health department says mothers-to-be should be smoke-free, not use alcohol or drugs, and have good dental health – not only during pregnancy but also before.

The department's Sheila Sjolander says gum disease in the mother can trigger premature birth.  In addition, she says, obesity is a major indicator of the likelihood of premature labor, so if the mother is overweight, she's likely to deliver early.

For more information, visit www.marchofdimes.com/39weeks .