How many visits by health professionals are needed to make a difference in low birthweight? A dose-response study of the Toronto Healthiest Babies Possible program.

The association of risk factors such as smoking, nutrition and adolescence with low birthweight has been well documented. What is less known is the extent to which certain program interventions can mediate the impact of these risks on low birthweight and the level of intervention necessary to have an impact. This study had two objectives: (a) to explore the role of the Toronto Healthiest Babies Possible (HBP) program as a mediator of the impact of smoking, adolescence, prepregnancy underweight and erratic weight gain/initial weight loss on LBW, and (b) to determine the dose-response relationship between the number of home visits and LBW. Study results suggest that the HBP strategy is making a difference for clients with the aforementioned three risk factors, and that the most effective intervention "dose" to reduce low birthweight is 9-11 visits. This type of study may serve as a benchmark in the evaluation of other similar programs.