OBJECTIVE: to explore how information about being at risk of carrying a fetus with Down's syndrome was understood, and whether the actual risk and the woman's perception of risk was associated with worry or depressive symptoms during and after pregnancy. DESIGN AND SETTING: observational study. The sample was drawn from the intervention group of a Swedish randomised controlled trial of ultrasound screening for Down's syndrome by nuchal translucency measurement. MEASUREMENTS: data were collected by three questionnaires. Questions were asked about recall of the risk score and perception of risk. The Cambridge Worry Scale and the Edinburgh Postnatal Depression Scale measured worry and depressive symptoms, respectively, on all three occasions. FINDINGS: of the 796 women who provided data for this study, one in five was unaware that the risk score was noted in her case record. In total, 620 women stated that they had received a risk score, but only 64% of them recalled the figure exactly or approximately. The actual risk was associated with the perceived risk, but of the 31 women who perceived the risk to be high, only 14 were actually at high risk. A high-risk score was not associated with worry or depressive symptoms in mid-pregnancy, in contrast to a woman's own perception of being at high risk. Two months postpartum, no associations were found between maternal emotional well-being and actual or perceived risk. CONCLUSIONS: information about fetal risk is complicated and women's perception of risk does not always reflect the actual risk, at least not when presented as a numerical risk score. The possibility that the information may cause unnecessary emotional problems cannot be excluded. IMPLICATIONS FOR PRACTICE: caregivers should ascertain that information about fetal risk is interpreted correctly by pregnant women.