We have recently carried out a study of 100 mothers at Queen Charlotte's Hospital, at 32 weeks' gestation, and shown that those who were most anxious had impaired blood flow through the uterine arteries. This may help to explain why the babies of very anxious mothers tend to be smaller or born earlier. We have also shown that there is a strong correlation between plasma levels of the stress hormone cortisol in the mother and in the fetus. If the pregnant mother has raised cortisol, this may have a direct effect on the development of the fetal brain, and affect the child's later responses to stress.