Exposure to drugs and other possibly harmful factors during the first trimester of pregnancy. Comparison of two prospective studies performed in Sweden 10 years apart.

474 women in mid-pregnancy, interviewed at ten different hospitals in Sweden, were questioned on a number of social and medical items: e.g., drug use, contraceptive technique used before pregnancy, exposure to possibly deleterious factors in the environment. The study, compared with a similar study made ten years earlier in Sweden, showed little or no difference in the use of iron and/or vitamin preparations, analgesic drugs, antibiotics, or endocrine drugs; but a drastic reduction is noted in the use of psychotropic drugs and of antihistaminic drugs. A marked decrease in frequency of first trimester X-ray exposures can be found, but no marked changes in smoking habits. Appr. 18% of the women used contraceptive pills within 6 months of becoming pregnant---3 had used them during early pregnancy. About 4% (18 women) had used IUD---one became pregnant with a Cu-UID (intra-uterine device inpregnated with copper).This type of study can provide some information on the prevalence of relatively common factors, but it must be considerably extended in order to permit an analysis of rare events, e.g., use of most drugs.