There were no explicit time constraints applied, but the interviews lasted between 15 and 40 minutes. Data were analysed thematically, according to the principles of qualitative description. Further information about how the conduct of the interviews met the consolidated criteria for reporting of qualitative research is shown in appendix S1. We interviewed 21 health professionals by telephone: four consultants in obstetrics and gynaecology, eight community based consultants in sexual and reproductive health, seven general practitioners, one sexual health specialist nurse and one midwife. In this study, awareness of preconception health CUDC-907 citations issues was generally low among women and health professionals. The high level of pregnancy planning contrasts with low levels of information acquired about pre-pregnancy health and low uptake of folate, even in women with a poor obstetric history or relevant medical condition. However, we found that the three months before pregnancy was a time when women who smoked cigarettes or drank alcohol were quite likely to cut down or quit these risk behaviours. Furthermore, women who received advice from a health professional before pregnancy were more likely than other women to adopt positive behaviour change before pregnancy, particularly taking folic acid and eating a healthier diet. For these reasons, our study presents good evidence to counter widely held perceptions that pregnancy planning is uncommon so there is little to be gained from targeting the preconception period. Rather it points to the need for more effective preconception health promotion to women with greater engagement and training of health professionals. The strengths of this study are the combination of qualitative and quantitative data, the high response rate and collection of data before the outcome of the pregnancy was known. The high response rate may reflect the face-to-face recruitment and interest in the topic, or perhaps long waiting times when attending the antenatal service. We also used a more robust measure of pregnancy planning than most other studies. The London Measure of Unplanned Pregnancy is a simple 6-item questionnaire with established psychometric properties that scores the ‘plannedness’ of a pregnancy from 0 to 12. It is valid for a current or recent pregnancy. The LMUP represents a significant methodological advance over other; often binary measures of pregnancy planning that are too blunt to capture the reality for most women. Weaknesses include retrospective reporting of pre-pregnancy behaviours with the potential for social desirability bias. The significant association between health professional input and preconception behaviour change could be explained by reporting bias and/or confounding, that is, if women who receive input from health professionals are more likely to report and/or adopt health pre-pregnancy behaviours irrespective of any input received. However, the ‘dose effect’ of health professional advice on changing to a healthier diet and taking folic acid that remained.