Prenatal pharmaceutical use was widespread from the 1950s through the early 1970s, based partly on the belief that medications could protect pregnancies deemed at-risk while posing no risk to the fetus. The drugs used, including progestins, estrogens, corticosteroids, barbiturates, morning sickness medications, and many other drugs used to treat a variety of conditions, were often administered from the very beginning of pregnancy, and millions of women around the world were treated with them. Many of these drugs are no longer in use, but prenatal pharmaceutical use continues to be widespread today, in spite of the lack of examination of potential effects on the descendants of children exposed to prenatal chemicals. This study will be the first to examine potential developmental abnormalities in humans, specifically in the grandchildren of Danish women given prenatal pharmaceuticals in the period from 1969-71. The study will use existing registers to ascertain abnormal outcomes in the offspring of the exposed individuals (those who were embryos and fetuses at the time of the exposures, but who are now 41-43 years old), and also directly contact them with a questionnaire about the development of their offspring. These studies will look for an array of neurological consequences, transmitted from generation to generation, and will greatly inform our understanding of the development of simple learning disabilities to the most severe of autism spectrum disorders.