UNWANTED EFFECTS OF ANTICONVULSANT DRUGS

However, some recent studies8, lo seem to be reasonably reassuring. Nevertheless, until more is known about the possible harmful effects, it would seem advisable to reduce the number of scans carried out during pregnancy. This, of course, will apply more to scans in early pregnancy rather than to measurements of the biparietal diameter. Assessments of the biparietal diameter are impossible before ten weeks since the fetal head is not formed and measurements are unsatisfactory before sixteen weeks. The most accurate time for maturity assessments is between twenty and thirty-four weeks. Accurate assessments of the duration of pregnancy can be made in the very early weeks, and such measurements would be of obvious value in doing serial estimations to assess fetal growth. Keeping in mind the possible inaccuracies, and limiting the number of scans done during pregnancy, ultrasonic measurement of the biparietal diameter is an extremely useful aid to the obstetrician. IAN MACGILLIVR.4Y Department of Obstetrics and Gynaecology, University of Aberdeen, Foresterhill, Aberdeen AB9 2ZD.