To examine what sources of health information are preferred by first-time mothers-to-be and how these preferences change by the time their child reaches school age. Women expecting their first child (n = 649), recruited in a randomized trial of early childhood caries prevention at all five public maternity hospitals in Adelaide, were questioned about their preferences for health information. Their preferences were assessed again 4 and 7 years later. Answers at 7 years were compared with those of a population-based cohort of mothers with a first child of the same age. Parents were listed most frequently as a preferred source of health information during pregnancy (67.8%) followed by health care practitioners (48.8%). By the time the child reached school age, 78% listed health care practitioners as their preferred source compared with 15.5% listing parents, 21.7% friends and relatives, and 13% the Internet. Data from the population-based comparison group of mothers with a first child of similar age mimicked those of mothers enrolled in the trial. Mothers put a lot more trust in information received from health care professionals than they did before their child was born. This can create opportunities for enhancing the effectiveness of community health initiatives.