Prenatal ultrasound scans are believed to enable mothers to form an early affectionate bond to their child, to provide a reassuring image of the fetus, and to promote improvements in mothers' health behaviors on the behalf of the fetus. Observational studies suggest that scans done early may slightly improve maternal-fetal bonding but that those done after quickening are not associated with attachment. Short-term effects on maternal health behaviors, including less smoking, less drinking of alcohol, and more visits to dentists, were detected in a randomized trial when detailed information was given during the scan. This trial also suggested that women's anxiety was actually increased during scans, and then allayed by positive feedback from the operator. Not all women considered scans reassuring in one interview study, and other authors found that mothers' interpretations of scans depended on their personal and social circumstances. As used in everyday practice, ultrasound scans are not always accompanied by feedback, and when feedback occurs it is sometimes in the form of slips of the tongue, incorrect diagnoses, identification of structures that cannot be deciphered, and language that is unfamiliar and alarming to mothers. This "diagnostic toxicity" of ultrasound scans of the fetus has not been studied.