MinervaBMJ 1995; 311 doi: https://doi.org/10.1136/bmj.311.7019.1582 (Published 09 December 1995) Cite this as: BMJ 1995;311:1582
- M R SHETTY, medical oncologist
- Northwest Community Hospital, IL 60005, USA
High doses of vitamin A in early pregnancy may be teratogenic. In a prospective study of over 22000 pregnant women (New England Journal of Medicine 1995;333;1369-73) the ratio of the prevalence of birth defects among babies born to women who consumed over 10000 IU a day of vitamin A in the form of dietary supplements to that among women who consumed 5000 IU or less was 4.8 (95% confidence interval 2.2 to 10.5). But, as the accompanying editorial warns, this message should not be allowed to confuse pregnant women and put them off taking folic acid supplements.
Smoking of marijuana by teenagers in the United States has doubled since 1992 (“Nature Medicine” 1995;1:1113). Expert opinion suggests that many of the parents of these teenagers may have smoked marijuana themselves when younger and may have ambivalent attitudes to the drug. On the plus side, casual use of cocaine seems to have declined.
Varicose veins are widely believed to increase a patient's risk of developing deep vein thrombosis, but there is little evidence to support that association. A questionnaire was sent to 363 vascular surgeons (British Journal of Surgery 1995;82:1494-7), and 289 replied; only 29% thought that varicose veins were an important risk factor, …