- Email: [email protected]
ASPIRIN AND POSTOPERATIVE VENOUS THROMBOSIS
48 real lack of scientific data to support them. The first two contentions have yet to be demonstrated in a field situation. A weakness of the third argument is that nutritional supplements may actually discourage lactation through a substitution effect. Supplements may also diminish the suck reflex, thereby shortening the period of postpartum amenorrhaea. The fourth proposition remains controversial with more prejudice and belief than hard scientific scrutiny. The health and nutritional benefits of successful familyplanning programmes are not inconsiderable. Dr. Gopalan and Mr. Naidu reported on the correlation of low dietary food intake with large family size. Sufficient data are also available to conclude that short birth intervals and high parity lead to high infant and maternal mortality-rates.5 Lowered birth-rates are essential to reduce the overwhelming demand for health services which swamp existing health facilities. Although difficult to measure, the most important health impact of reduced birth-rates may be improved economic well-being. Studies on the determinants of malnutrition have shown that low purchasing power is the most important xtiological factor causing malnutrition.6 Rapid population growth remains a large impediment toward an acceleration of economic development in most of the developing world. This discussion of " mutual benefits " is far from complete. It serves to underscore the real scarcity of sound scientific knowledge in this critical area. Insufficient understanding of these interactions inhibits the planner’s ability to allocate scarce health and family-planning resources effectively. Further research in elucidating the important relationship between health and family planning are badly needed. "
"
School of Hygiene and Public Health,
Johns Hopkins University, Baltimore, Maryland 21205, U.S.A.
LINCOLN C. CHEN.
NUTRITION AND THE DEVELOPING BRAIN
SIR,-Your leading article (Dec. 23, p. 1349) refers to important question whether early malnutrition leads
the
deficits in later intelligence. In another part of the same issuethe question is asked whether maternal smoking during pregnancy has any long-term effect on the child’s intellectual development ? The two questions are related, since it seems possible that the permanent physical effects of undernutrition on the developing brain are mainly the consequence of the resulting growth retardation, rather than of its specific nutritional or other cause. In spite of the many claims that protein malnutrition, for example, has a specific long-term effect on the developing brain, there is at present no experimental evidence that differences between this and other forms of dietary restriction produce different changes when the degree of growth retardation is held constant. It seems much more likely that it is the intricate programme of normal brain development which is non-specifically disrupted by restrictions of bodily growth during the period of the brain growth spurt.* In this way any growth-retarding influence to
of appropriate severity and duration, but above all correctly timed to cover the period of the brain growth spurt, may be expected to produce similar lasting changes in the physical brain. The key to the problem is knowledge of the timing of the human brain growth spurt, which we know to extend from mid-pregnancy into at least the Moderate growth restriction second postnatal year. throughout this period, or particularly severe restriction for an important proportion of it, is theoretically necessary to produce permanent changes. This we have learned from animal experiment. The fetus of the smoking mother on this hypothesis is released from his growth restriction when he is born, with about six-sevenths of his brain growth spurt period still to come, giving ample opportunity for virtually complete catch-up: and this corresponds with what Hardy and Mellits found.7 On the question whether malnutrition before the age of two results in slight deficits in intelligence ", I am much less hesitant than you. I believe the possible intellectual deficits to be gross, not slight, and my main evidence is the very careful recent study of Jamaican children by Birch, Tizard, and colleagues 9 which you do not mention, and in which your caveats about control groups are carefully considered. Much confusion of thought has unhappily resulted from a previous, erroneous report implying that the human brain growth spurt is over by about five postnatal months.lo When it is realised that it continues much longer than this, the failure of Birch and Tizard to detect different degrees of ultimate deficit in children malnourished at different times within the first two postnatal years may be better understood. On the available evidence may we now beg pxdiatricians, and more especially politicians, to accept the whole of the human brain growth spurt period, from mid-pregnancy well into the second postnatal year, as a period, not only of brain vulnerability, but of opportunity actively to promote the proper growth of the human brain, by providing the best possible environmental conditions ? There is evidence that this opportunity is chronologically determined and it only knocks once."
now
"
Department of Child Health, University of Manchester, Clinical Sciences Building, York Place, Manchester M13 0JJ.
JOHN DOBBING.
significant
5. Omran, A. R. The Health Theme in
Family Planning. Monograph
16, Carolina Population Center, University of North Carolina, 1971. 6. Call, D. L., Levinson, F. J. International Conference on Nutrition, National Development, and Planning. Massachusetts Institute of Technology. Oct. 19-21, 1971. 7. Hardy, J. B., Mellits, E. D. Lancet, 1972, ii, 1332. 8. Dobbing, J. in Lipids, Malnutrition and the Developing Brain. Amsterdam, 1972.
ASPIRIN AND POSTOPERATIVE VENOUS THROMBOSIS
SIR,-In reply to Dr. Mayrhofer’s criticism (Dec. 16, p. 1311) of the low single dose of aspirin given daily in the M.R.C. trial, I have to point out that the object of treatment was not to maintain a detectable level of aspirin or salicylate in the plasma but to render the platelets abnormal. After a single dose of 600 mg. it was shown that the platelets remained incapable of giving a normal release reaction and responding normally to collagen for at least 48 hours. In fact, as mentioned in our report, a small trial with 06 g. four times a day was also undertaken 12 and again the incidence of thrombosis detected by the 125I-fibrinogen method remained unaltered. University Park, Nottingham NG7 2RD. 9. 10. 11. 12.
W.
J. H. BUTTERFIELD.
Hertzig,M. E., Birch, H. G., Richardson, S. A., Tizard, J. Pediatrics. 1972, 49, 814. Winick, M. Pediat. Res. 1968. 2, 352. Dobbing, J., Sands, J. Biol. Neonat. 1971, 19, 363. O’Brien, J. R., Tulevski, V., Ethenngton, M. Lancet, 1970, i, 399.
"
School of Hygiene and Public Health,
Johns Hopkins University, Baltimore, Maryland 21205, U.S.A.
LINCOLN C. CHEN.
NUTRITION AND THE DEVELOPING BRAIN
SIR,-Your leading article (Dec. 23, p. 1349) refers to important question whether early malnutrition leads
the
deficits in later intelligence. In another part of the same issuethe question is asked whether maternal smoking during pregnancy has any long-term effect on the child’s intellectual development ? The two questions are related, since it seems possible that the permanent physical effects of undernutrition on the developing brain are mainly the consequence of the resulting growth retardation, rather than of its specific nutritional or other cause. In spite of the many claims that protein malnutrition, for example, has a specific long-term effect on the developing brain, there is at present no experimental evidence that differences between this and other forms of dietary restriction produce different changes when the degree of growth retardation is held constant. It seems much more likely that it is the intricate programme of normal brain development which is non-specifically disrupted by restrictions of bodily growth during the period of the brain growth spurt.* In this way any growth-retarding influence to
of appropriate severity and duration, but above all correctly timed to cover the period of the brain growth spurt, may be expected to produce similar lasting changes in the physical brain. The key to the problem is knowledge of the timing of the human brain growth spurt, which we know to extend from mid-pregnancy into at least the Moderate growth restriction second postnatal year. throughout this period, or particularly severe restriction for an important proportion of it, is theoretically necessary to produce permanent changes. This we have learned from animal experiment. The fetus of the smoking mother on this hypothesis is released from his growth restriction when he is born, with about six-sevenths of his brain growth spurt period still to come, giving ample opportunity for virtually complete catch-up: and this corresponds with what Hardy and Mellits found.7 On the question whether malnutrition before the age of two results in slight deficits in intelligence ", I am much less hesitant than you. I believe the possible intellectual deficits to be gross, not slight, and my main evidence is the very careful recent study of Jamaican children by Birch, Tizard, and colleagues 9 which you do not mention, and in which your caveats about control groups are carefully considered. Much confusion of thought has unhappily resulted from a previous, erroneous report implying that the human brain growth spurt is over by about five postnatal months.lo When it is realised that it continues much longer than this, the failure of Birch and Tizard to detect different degrees of ultimate deficit in children malnourished at different times within the first two postnatal years may be better understood. On the available evidence may we now beg pxdiatricians, and more especially politicians, to accept the whole of the human brain growth spurt period, from mid-pregnancy well into the second postnatal year, as a period, not only of brain vulnerability, but of opportunity actively to promote the proper growth of the human brain, by providing the best possible environmental conditions ? There is evidence that this opportunity is chronologically determined and it only knocks once."
now
"
Department of Child Health, University of Manchester, Clinical Sciences Building, York Place, Manchester M13 0JJ.
JOHN DOBBING.
significant
5. Omran, A. R. The Health Theme in
Family Planning. Monograph
16, Carolina Population Center, University of North Carolina, 1971. 6. Call, D. L., Levinson, F. J. International Conference on Nutrition, National Development, and Planning. Massachusetts Institute of Technology. Oct. 19-21, 1971. 7. Hardy, J. B., Mellits, E. D. Lancet, 1972, ii, 1332. 8. Dobbing, J. in Lipids, Malnutrition and the Developing Brain. Amsterdam, 1972.
ASPIRIN AND POSTOPERATIVE VENOUS THROMBOSIS
SIR,-In reply to Dr. Mayrhofer’s criticism (Dec. 16, p. 1311) of the low single dose of aspirin given daily in the M.R.C. trial, I have to point out that the object of treatment was not to maintain a detectable level of aspirin or salicylate in the plasma but to render the platelets abnormal. After a single dose of 600 mg. it was shown that the platelets remained incapable of giving a normal release reaction and responding normally to collagen for at least 48 hours. In fact, as mentioned in our report, a small trial with 06 g. four times a day was also undertaken 12 and again the incidence of thrombosis detected by the 125I-fibrinogen method remained unaltered. University Park, Nottingham NG7 2RD. 9. 10. 11. 12.
W.
J. H. BUTTERFIELD.
Hertzig,M. E., Birch, H. G., Richardson, S. A., Tizard, J. Pediatrics. 1972, 49, 814. Winick, M. Pediat. Res. 1968. 2, 352. Dobbing, J., Sands, J. Biol. Neonat. 1971, 19, 363. O’Brien, J. R., Tulevski, V., Ethenngton, M. Lancet, 1970, i, 399.