Tobacco, alcohol, and other drug use can lead to birth defects, low birth weight, and premature delivery (HHS, 2006). All of these are listed as the major causes of infant mortality (CDC). Given the literature and public service announcements produced on these subjects over the past several decades, it is difficult to believe that anyone in this country is unaware of the detrimental effects these things can have on a fetus, and apparently thee communications are working to a degree; the infant mortality rate has dropped significantly, and yet such abuse is still among the leading causes of infant death (CDC; HHS, 2006). To tackle these issues, information should not be the focus of the message strategy but rather the mothers themselves should be the message's focus. Perhaps a short bulleted list of the disadvantages children with fetal alcohol syndrome and other effects of in utero abuse are likely to face if they manage to survive would be an effective scare tactic, but more important is instilling...

They need to understand that their choices affect other lives, and illustrating an infant's helplessness would be more effective for this purpose. The message strategy here should be more emotive than cognitive.
I believe that almost all women would opt to have proper prenatal and maternal care if they knew it was available and affordable to them, which is why I believe an informative strategy would work best in this case. An emotive strategy is more effective in dealing with substance abuse, however, because it generally has an emotional cause.

References

Eliminate disparities in infant mortality." Center for disease control website (CDC). Accessed 31 January 2009. http://www.cdc.gov/omhd/AMH/factsheets/infant.htm

Health and human services fact sheet: Preventing infant mortality." (2006). Health and human services website (HHS). Accessed 31 January 2009. http://www.cdc.gov/omhd/AMH/factsheets/infant.htm