492
about 20%,7 8 and Wright and colleagues9 have recently discussed in detail the seronegative spondylarthritides, one of which is associated with psoriasis. Hence psoriasis, a common disorder, may coexist with rheumatoid arthritis, another common disorder, but is more often associated with an apparently identical arthritis which remains seronegative and is less aggressive and progressive. It may also present in the familiar distal form and also as a seronegative spondylarthritis, and sometimes as both. At the moment, therefore, there is enough evidence for us to accept psoriatic arthritis as an entity distinct and apart from rheumatoid arthritis, even though the manifestations are often similar or identical and even though patients with classical rheumatoid arthritis may also have coexistent psoriasis. Patients with psoriatic arthritis should by definition be seronegative and free from rheumatoid nodules. By splitting this disorder off from rheumatoid arthritis much more has been learnt about it, as these workers have clearly shown. Barber, H S, Annals of the Rheumatic Diseases, 1957, 16, 230. Gibberd, F B, Acta Rheumatologica Scandinavica, 1965, 11, 62. 3 Vilanova, X, and Pinol, J, Rheumatism, 1951, 7, 197. 4 Wright, V, Annals of the Rheumatic Diseases, 1956, 15, 348. 5Coste, F, et al, Revue du Rhumatisme et des Maladies Osteo-Articulaires, 1958, 25, 75. 6 Roberts, M E T, et al, Annals of the Rheumatic Diseases, 1976, 35, 206. Read, W B, Heiskell, C L, and Becker, S W, Archives of Dermatology, 1961, 83, 653. Wright, V, Annals of the Rheumatic Diseases, 1961, 20, 123. 9 Wright, V, Sturrock, R D, and Dick, W C, in Recent Advances in Rheumatology, Part 2, eds W W Buchanan and W C Dick, p 193. London, Churchill Livingstone, 1976. 2
Cigarette smoking in pregnancy Cigarette smoking often constitutes an addiction or provides a form of escape from anxiety about personal problems. But smoking in pregnancy presents a special case. Firstly, it is a danger to the child as well as to the mother. Secondly, since pregnancy is of limited duration a woman who cannot be persuaded to give up smoking may accept a substitute at least while she is pregnant. It would be an advance if her craving could be met by a cigarette free from dangers to the baby. Accordingly, workers have tried to identify the harmful components of tobacco smoke. Carbon monoxide, nicotine, and cyanides are the factors which seem most likely to have ill effects on the fetus. Studies of carbon monoxide'-3 have indicated that the increase in carboxyhaemoglobin may deprive the fetus of adequate oxygen. Epidemiological evidence suggests that the type of baby liable to be harmed by the mother's smoking is the one already at risk for some other reason. Nevertheless, analysis of oestriol excretion levels has suggested that hypoxia is not the main influence on retardation of fetal growth.4 Large doses of nicotine injected into pregnant rats reduce birth weight.5 Suzuki et a16 injected nicotine into pregnant rhesus monkeys and concluded that the concentration produced by maternal smoking would reduce the fetal oxygenation. In man Gennser et al7 compared the effects of nicotine in chewing-gum at two strengths, tobacco cigarettes, and nontobacco cigarettes. They measured changes in fetal respiratory movements and maternal blood nicotine and carboxyhaemoglobin levels. The tobacco cigarettes and both strengths of nicotine chewing-gum raised the nicotine level and the tobacco
BRITISH MEDICAL JOURNAL
28 AUGUST 1976
and non-tobacco cigarettes raised the carboxyhaemoglobin level, but for each measurement the tobacco cigarette had the greatest effect. Fetal breathing was depressed with the tobacco cigarette and slightly less so with the nicotine chewing-gum. A more recent study has confirmed that fetal breathing movements are reduced in association with cigarette smoking in normal and abnormal pregnancies.8 The reduction was related to the rise in maternal plasma nicotine levels. Nonnicotine (herbal) cigarettes produced similar rises in carboxyhaemoglobin to those caused by tobacco cigarettes but without a reduction in fetal breathing. These studies are helpful in dissociating the influence of nicotine from that of carbon monoxide in regard to this particular effect. Nevertheless, it does not follow that the effect on fetal respiration is of practical importance, though circumstantial evidence is accumulating that it may be.8 Thiocyanate concentrations are raised in the cord blood of infants born to smoking mothers,9 while vitamin B12 levels are lower in smokers. This may reflect a disorder of cyanide detoxification'0 related to the cyanide of the cigarette smoke. The lowered appetite which is a recognised concomitant of smoking may be responsible for a lower maternal calorific intake and hence lower fetal weight, but a review of the evidence in 1973 did not suggest that this mattered.} Since then, however, other workers have suggested that impaired gain in maternal weight may be of importance." What can be done practically? Until the metabolites which are dangerous to the fetus have been identified with certainty, efforts to substitute an alternative to tobacco cigarettes seem premature. Attempts to persuade the mother to reduce or preferably give up smoking offer the best prospect, though it is worth bearing in mind that a patient deprived of one satisfaction for her craving may try to resort to another. Smoking is best stopped before conception, but there is evidence that stopping in the first two months of pregnancy reduces the hazard.'3 Encouraging the mother to increase her food intake may be worth trying, but excessive weight gain may be harmful, and at present a controlled trial of this approach seems called for.'2 It is mothers in the lower social classes and with a poor obstetric performance whose babies are particularly at risk from smoking, and they might well be guided to special clinics so that maximal effort could be concentrated on them. Whatever his detailed approach, the obstetrician must take pains not to be so critical as to drive the patient away from the antenatal care which he offers but show compassionate understanding of a common human
frailty. 'Younoszai, M K, Kacic, A, and Haworth, J C, Canadian Medical Association Journal, 1968, 99, 197. 2Astrup, P, et al, Lancet, 1972, 2, 1220. 3Cole, P V, Hawkins, L H, and Roberts, D, Journal of Obstetrics and Gynaecology of the British Commonwealth, 1972, 79, 782. 4 Targett, C S, et al, J7ournal of Obstetrics and Gynaecology of the British 'Commonwealth, 1973, 80, 815. 5 Public Health Services, The Health Consequences of Smoking. A Report of the Surgeon General, 1973. Department of Health, Education and Welfare, DHEW Publication No. (HMS) 73-8704, 1973. 6 Suzuki, K, et al, AmericanyJournal of Obstetrics and Gynecology, 1971, 111, 1092. 7Gennser, G, Marsal, K, and Brantmark, B, American Journal of Obstetrics and Gynecology, 1975, 123, 861. 8 Manning, F A, and Feyerabend, C, British Jrournal of Obstetrics and Gynaecology, 1976, 83, 262. Andrews, J, Jrournal of Obstetrics and Gynaecology of the British Commonwealth, 1973, 80, 810. '0 McGarry, J M, and Andrews, J, British Medical Journal, 1972, 2, 74. Rush, D, Journal of Obstetrics and Gynaecology of the British Commonwealth, 1974, 81, 746. 12 Davies, D P, et al, Lancet, 1976, 1, 385. 13 Butler, N R, Goldstein, H, and Ross, E M, British Medical Journal, 1972, 2, 127.
about 20%,7 8 and Wright and colleagues9 have recently discussed in detail the seronegative spondylarthritides, one of which is associated with psoriasis. Hence psoriasis, a common disorder, may coexist with rheumatoid arthritis, another common disorder, but is more often associated with an apparently identical arthritis which remains seronegative and is less aggressive and progressive. It may also present in the familiar distal form and also as a seronegative spondylarthritis, and sometimes as both. At the moment, therefore, there is enough evidence for us to accept psoriatic arthritis as an entity distinct and apart from rheumatoid arthritis, even though the manifestations are often similar or identical and even though patients with classical rheumatoid arthritis may also have coexistent psoriasis. Patients with psoriatic arthritis should by definition be seronegative and free from rheumatoid nodules. By splitting this disorder off from rheumatoid arthritis much more has been learnt about it, as these workers have clearly shown. Barber, H S, Annals of the Rheumatic Diseases, 1957, 16, 230. Gibberd, F B, Acta Rheumatologica Scandinavica, 1965, 11, 62. 3 Vilanova, X, and Pinol, J, Rheumatism, 1951, 7, 197. 4 Wright, V, Annals of the Rheumatic Diseases, 1956, 15, 348. 5Coste, F, et al, Revue du Rhumatisme et des Maladies Osteo-Articulaires, 1958, 25, 75. 6 Roberts, M E T, et al, Annals of the Rheumatic Diseases, 1976, 35, 206. Read, W B, Heiskell, C L, and Becker, S W, Archives of Dermatology, 1961, 83, 653. Wright, V, Annals of the Rheumatic Diseases, 1961, 20, 123. 9 Wright, V, Sturrock, R D, and Dick, W C, in Recent Advances in Rheumatology, Part 2, eds W W Buchanan and W C Dick, p 193. London, Churchill Livingstone, 1976. 2
Cigarette smoking in pregnancy Cigarette smoking often constitutes an addiction or provides a form of escape from anxiety about personal problems. But smoking in pregnancy presents a special case. Firstly, it is a danger to the child as well as to the mother. Secondly, since pregnancy is of limited duration a woman who cannot be persuaded to give up smoking may accept a substitute at least while she is pregnant. It would be an advance if her craving could be met by a cigarette free from dangers to the baby. Accordingly, workers have tried to identify the harmful components of tobacco smoke. Carbon monoxide, nicotine, and cyanides are the factors which seem most likely to have ill effects on the fetus. Studies of carbon monoxide'-3 have indicated that the increase in carboxyhaemoglobin may deprive the fetus of adequate oxygen. Epidemiological evidence suggests that the type of baby liable to be harmed by the mother's smoking is the one already at risk for some other reason. Nevertheless, analysis of oestriol excretion levels has suggested that hypoxia is not the main influence on retardation of fetal growth.4 Large doses of nicotine injected into pregnant rats reduce birth weight.5 Suzuki et a16 injected nicotine into pregnant rhesus monkeys and concluded that the concentration produced by maternal smoking would reduce the fetal oxygenation. In man Gennser et al7 compared the effects of nicotine in chewing-gum at two strengths, tobacco cigarettes, and nontobacco cigarettes. They measured changes in fetal respiratory movements and maternal blood nicotine and carboxyhaemoglobin levels. The tobacco cigarettes and both strengths of nicotine chewing-gum raised the nicotine level and the tobacco
BRITISH MEDICAL JOURNAL
28 AUGUST 1976
and non-tobacco cigarettes raised the carboxyhaemoglobin level, but for each measurement the tobacco cigarette had the greatest effect. Fetal breathing was depressed with the tobacco cigarette and slightly less so with the nicotine chewing-gum. A more recent study has confirmed that fetal breathing movements are reduced in association with cigarette smoking in normal and abnormal pregnancies.8 The reduction was related to the rise in maternal plasma nicotine levels. Nonnicotine (herbal) cigarettes produced similar rises in carboxyhaemoglobin to those caused by tobacco cigarettes but without a reduction in fetal breathing. These studies are helpful in dissociating the influence of nicotine from that of carbon monoxide in regard to this particular effect. Nevertheless, it does not follow that the effect on fetal respiration is of practical importance, though circumstantial evidence is accumulating that it may be.8 Thiocyanate concentrations are raised in the cord blood of infants born to smoking mothers,9 while vitamin B12 levels are lower in smokers. This may reflect a disorder of cyanide detoxification'0 related to the cyanide of the cigarette smoke. The lowered appetite which is a recognised concomitant of smoking may be responsible for a lower maternal calorific intake and hence lower fetal weight, but a review of the evidence in 1973 did not suggest that this mattered.} Since then, however, other workers have suggested that impaired gain in maternal weight may be of importance." What can be done practically? Until the metabolites which are dangerous to the fetus have been identified with certainty, efforts to substitute an alternative to tobacco cigarettes seem premature. Attempts to persuade the mother to reduce or preferably give up smoking offer the best prospect, though it is worth bearing in mind that a patient deprived of one satisfaction for her craving may try to resort to another. Smoking is best stopped before conception, but there is evidence that stopping in the first two months of pregnancy reduces the hazard.'3 Encouraging the mother to increase her food intake may be worth trying, but excessive weight gain may be harmful, and at present a controlled trial of this approach seems called for.'2 It is mothers in the lower social classes and with a poor obstetric performance whose babies are particularly at risk from smoking, and they might well be guided to special clinics so that maximal effort could be concentrated on them. Whatever his detailed approach, the obstetrician must take pains not to be so critical as to drive the patient away from the antenatal care which he offers but show compassionate understanding of a common human
frailty. 'Younoszai, M K, Kacic, A, and Haworth, J C, Canadian Medical Association Journal, 1968, 99, 197. 2Astrup, P, et al, Lancet, 1972, 2, 1220. 3Cole, P V, Hawkins, L H, and Roberts, D, Journal of Obstetrics and Gynaecology of the British Commonwealth, 1972, 79, 782. 4 Targett, C S, et al, J7ournal of Obstetrics and Gynaecology of the British 'Commonwealth, 1973, 80, 815. 5 Public Health Services, The Health Consequences of Smoking. A Report of the Surgeon General, 1973. Department of Health, Education and Welfare, DHEW Publication No. (HMS) 73-8704, 1973. 6 Suzuki, K, et al, AmericanyJournal of Obstetrics and Gynecology, 1971, 111, 1092. 7Gennser, G, Marsal, K, and Brantmark, B, American Journal of Obstetrics and Gynecology, 1975, 123, 861. 8 Manning, F A, and Feyerabend, C, British Jrournal of Obstetrics and Gynaecology, 1976, 83, 262. Andrews, J, Jrournal of Obstetrics and Gynaecology of the British Commonwealth, 1973, 80, 810. '0 McGarry, J M, and Andrews, J, British Medical Journal, 1972, 2, 74. Rush, D, Journal of Obstetrics and Gynaecology of the British Commonwealth, 1974, 81, 746. 12 Davies, D P, et al, Lancet, 1976, 1, 385. 13 Butler, N R, Goldstein, H, and Ross, E M, British Medical Journal, 1972, 2, 127.
