BMC Public Health 2007, 7:322 http://www.biomedcentral.com/1471-2458/7/322 specialised clinic organised within the ordinary primary health care system. The substance abusers had substantial substance problems compared to other studies [25,30]. The incidence of substance abusing pregnant women in the SCWC was 6.1 per 1000 in the years 1994–2002 [31]. The number of substance abusing women differs in differ- ent studies [25,32] with lower incidences in studies from Scandinavia. Treatment is only necessary for the women that are addicted, and therefore unable to stop the sub- stance abuse during pregnancy. Our validation based on figures from the diagnosis register in the regional hospital confirms that the majority of women with substance addiction in need of special treatment in this area have been in contact with SCWC. There are several limitations to this investigation. We have used no tools for assessing the severity of addiction. The substances used before and during pregnancy are regis- tered in the medical records and in the questionnaire. The SCWC is a part of the primary health care system of the community of Kristiansand in which there is little tradi- tion for registering the severity of addiction. Treatment is provided whenever the necessary motivation is obtained, and the registration of addiction in the medical journals is therefore not very detailed. Other studies have shown that information concerning substance abuse given in ques- tionnaires is reliable if there are no other interests influ- encing the answers given [33,34]. In our study there might have been a fear of legal sanctions. However, in all cases there were persons in the network groups that already knew about the substance abuse, and our experience is that the correct information was given. The diagnosis of psychiatric disease was done by the patient's regular doctor or a psychiatrist. In the records at the SCWC we only registered self reported psychiatric diagnosis and those who had psychotropic medication during pregnancy. As psychiatric disease changes over time, our registration may not be complete. In pregnancy the treatment is voluntarily. We were in the beginning anxious that the users of the SCWC would drop out of treatment if we were too determined about urine specimens. Some of the women did not want to give urine specimens, and therefore there might be some uncertainty about their drug abuse in pregnancy. When investigating the effects of such interventions as those given by the SCWC, it would scientifically have been preferable to have randomised the group in two, where one group had no intervention. Ethically, however, it would be unacceptable to withhold a much needed inter- vention from a group of pregnant substance abusing women. Our comparison group therefore had to be selected from a normal population. The comparison group consisted of the parents of children coming to their child welfare clinic or coming to parents conferences at school. Both teachers and parents were given information about the project in advance, and the parents also got fur- ther information when arriving to the conference. They all expressed a positive attitude to the study. Most parents kept their appointment with the child welfare clinic or school, so very few questionnaires needed to be sent to the homes. When questionnaires were sent to the homes, the appointment was to return the questionnaire with the pupil to the teacher. This might explain why we got answers from all who were asked. Because of cultural differences it is important to try to identify predictors for reducing substance abuse during pregnancy for substance abusing women in Scandinavia, as the available results in the literature generally are taken from other regions. Future studies would improve on more accurate diagnosis on the level of addiction which can be obtained in closer cooperation with hospitals and treatment institutions for drug abuse, and also there should be a closer follow up by means of urine specimens. Conclusion A low cost and low threshold initiative organised as a child welfare clinic may support substance abusing women in stopping or reducing their substance abuse dur- ing pregnancy. Abbreviations SCWC – Special Child Welfare Clinic. Competing interests The author(s) declare that they have no competing inter- ests. Authors' contributions BH conceived of the study and participated in its design, did the statistical analyses and wrote the manuscript. She has also been the doctor at the SCWC since its inception. ML and EOR participated in the design of the study, helped with statistical analyses and helped draft the man- uscript. All authors read and approved the final manu- script. Additional material Additional file 1 Level of education, employment and economy. Level of education, employ- ment and economy of the 102 users of Special Child Welfare Clinic (SCWC) in Kristiansand, Norway, in the years 1994–2002. Click here for file [http://www.biomedcentral.com/content/supplementary/1471- 2458-7-322-S1.pdf] Page 6 of 8 (page number not for citation purposes)