For personal use only. Not to be reproduced without permission of The Lancet. RESEARCH LETTERS See Commentary page 1704 A survey of the records of the French Health Insurance Service of drug prescriptions during pregnancy in 1000 women living in Haute-Garonne, southwest France, showed that 99% of the women received a prescription for at least one drug during pregnancy with a mean of 13·6 medications per woman. 1·6% of women received one or more prescriptions of drugs from the US Food and Drug Administration X category (fetal risk outweighs benefits). 59% of women had a prescription of drugs from the D category (fetal risk but benefits may be acceptable) and 79% of women were exposed to drugs for which information about safety in pregnancy was not available from animal or human studies. Because pregnant women are excluded from clinical trials, it is impossible to assess the teratogenic potential of drugs in women during the premarketing period. Many women take drugs during pregnancy, but the extent of drug prescription and the types of drugs prescribed are difficult to ascertain. 1–3 To collect reliable information about drug prescriptions in pregnant women, we did a retrospective survey of the records of the Caisse Primaire d’Assurance Maladie de la Haute-Garonne, which represents the French Health Insurance System (86% of the population) in this area in southwest France. We examined all the original prescription forms issued throughout the whole pregnancies of 1000 women. To avoid potential seasonal variations, we randomly selected 500 women who had their babies in May and June, 1996, and 500 who had them in November and December, 1996, in Haute-Garonne. The women gave their consent for us to use prescription records related to their pregnancies. Data were collected directly from the original prescriptions. Subsidised as well as non-subsidised drugs were recorded. The womens’ ages ranged from 17 years to 47 years with a mean age of 29·8 years (SE 4·2). The mean length of gestation was 39·8 weeks (2·4). The rate of delivery before 35 weeks of pregnancy was 4·3%. We examined 8135 prescription forms (mean 8·2 forms per woman) of 18 860 prescribed medications, with a mean of 13·6 (5·8) different prescribed proprietary preparations and 15·8 (5·9) prescribed non-proprietary medicinal substances per woman. Only ten (1%) women had no drug prescription during pregnancy. Six (0·6%) women had more than 50 different prescribed proprietary preparations. The mean number of prescribed drugs per woman was lower in the first trimester of pregnancy (5·2 [3·0]) than in the second (7·1 [3·1]) or the third trimester (6·6 [3·1]). Prescription forms mainly came from family physicians (49%) or gynaecologists (41%). There was no statistical difference in the number of prescribed drugs between the two seasonal periods. When expressed as a percentage of exposed women, the most commonly prescribed classes of drugs were iron (74·9%), gastrointestinal drugs (69·4%), dermatological THE LANCET • Vol 356 • 18 November, 2000 1735 Research letters Prescription of drugs during pregnancy in France I Lacroix, C Damase-Michel, M Lapeyre-Mestre, J L Montastruc 1000 800 Iron Gastrointestinal Dermatological Analgesic Gynaecological (excluding anti-infectives) Other respiratory Folic acid Cardiovascular system Antibiotics (systemic) Minerals Gynaecological anti-infectives/antiseptics Vitamins Rheumatic drugs Other central nervous system preparations Homoeopathics Others Ophthalmological/otological preparations Non-steroidal anti-inflammatory drugs Systemic corticosteroids Thyroid hormones 600 Number of exposed women 400 200 0 Figure 1: Types of drugs prescribed (according to ATC code)