Abstract This paper reviews the literature on intellectual change during and following pregnancy in humans. Whilst much has been written in an impressionistic way, this area has received little serious scientific attention, and at the beginning of the twenty first century considerable gaps in our knowledge remain. Targets for future research are suggested. The second part of the paper reviews the complex hormonal changes that place during pregnancy and birth and examines the impact that these changes may have on cognition, drawing together the findings from a number of scientific fields. Whilst this review may generate more questions than it answers, we hope that it will create interest and stimulate research in this long neglected field.