178

given, long-term low-dosage prophylaxis prevents further infection of the unobstructed urinary tract. This is in keeping with previous uncontrolled studies of prophylaxis and a recent controlled trial of nitrofurantoin.12 In the trial reported here, only children with symptomatic infection of radiologically normal urinary tracts were studied but the value of low-dosage prophylaxis has previously been demonstrated in uncontrolled studies of children with vesico-ureteric reflux, renal scarring, or morphological anomalies such as duplex kid-

ney.11,13—15

REFERENCES 1.

Kunin,

C.

M., Deutscher, R., Paquin,

91.

It must be

emphasised that low-dosage prophylaxis will not prevent persisting or recurrent infection if there is continuing urinary stasis, or obstruction to urinary outflow which needs surgical relief. The established relation between an increased residual urine and recurrence of infection 16, 17 and the association of constipation and urinary infection,’8 suggest that regular complete bladder emptying and the prevention of faecal overloading are important in preventing further infection. There was no significant difference in the incidence of recurrence in the year after only a short course of antibacterial treatment and in that following prophylaxis, but when the previous history of infection was taken into account, the observed differences in recurrence in the two groups was significant. Prophylaxis may have provided time for the inflamed bladder mucosa to recover or for the defect in bladder defence to be corrected. These results, together with the finding that at least 90% of the further infections were reinfections, support the view that the main cause of recurrent infection in the absence of outflow obstruction is a breakdown of the host defences,19,20 allowing colonisation of the susceptible bladder by bowel commensals ascending the urethra. It follows that the effect upon the bowel flora of different antibacterial drugs and of the dosage used to eradicate the presenting infection or in subsequent prophylaxis is of considerable importance, especially in determining the nature and sensitivity of a further infection. In all the recurrences tested the predominant faecal organism was identical with the urinary organism so that a rectal swab may be of predictive therapeutic value. As in our earlier studies,21,22 we found an almost immediate reduction in the bowel coliform population both after full-dosage and during low-dosage co-trimoxazole treatment, with a rapid return to normal counts of sensitive organisms on its withdrawal. No trimethoprim or nitrofurantoin resistance developed during this study. There was no increase, during prophylaxis, of the level of sulphonamide-resistance normally found and this was evenly distributed between the groups. The difference between the two groups in symptomatology and timing of reinfections is of some interest in view of recent reports of differences in the strains of organisms causing symptomatic and asymptomatic bacteriuria.23,24 Clearly low-dosage antibacterial prophylaxis with cotrimoxazole or nitrofurantoin prevents recurrence of urinary infection in the unobstructed urinary tract. Its principal use at present is to control recurrent symptomatic infections and to prevent infection in infants and children with vesicoureteric reflux. We thank Dr Peter

for technical microbiological assistance; Sister March and staff of the Children’s Department, University College Hospital for their help; local general practitioners for referring untreated children for diagnosis ; Mrs Marjorie Bedford for secretarial help; and Mr P. Fayers and Dr A. Johnson of the Medical Research Council Statistical Research Unit. This study was supported by a grant from the Medical Research Council. Requests for reprints should be addressed to J.M.S., Paediatric Department, University College Hospital, Huntley Street, London WC1E 6AU

Wimberley for help in the clinics; Mrs A. Leakey

A.

Medicine, (Baltimore), 1964, 43,

2.

Bergström, T., Lincoln, K., Redin, B., Winberg, J. Acta pœdiat. scand. 1968, 57, 186. 3. Grüneberg, R. N., Smellie, J. M., Leakey, A. in Urinary Tract Infection II, (edited by W. Brumfitt and A. W. Asscher); p. 131. London, 1973. 4. Normand, I. C. S., Smellie, J. M. Br. med. J. 1965, i, 1023. 5. MacGregor, M., Freeman, P. Q.Jl Med. 1975, 44, 481. 6. White, R. H. R. Br. med. J. 1977, i, 1650. 7. King, L. R., Kazmi, S. O., Belman, A. B. Urol. Clin. N. Am. 1974, 1, 441. 8. Govan, D. E., Fair, W. R., Friedland, G. W., Filly, R. A. Urology, 1975, 6, 273. 9.

O’Grady, F., Fry, I. K., McSherry, A., Cattell, W. R. J. infect. 128, (suppl), S652. 10. Bailey, R. R., Gower, P. E., Roberts, A. P., de Wardener, H.

Dis.

1973,

P. Lancet, 1971, ii, 1112. 11. Smellie, J. M., Grüneberg, R. N., Leakey, A., Atkin, W. S. Br. med. J. 1978, ii, 203. 12. Lohr, J. A., Nunley, D. H., Howards, S. S., Ford, R. F. Pediatrics, Springfield, 1977, 59, 562. 13. Edwards, D., Normand, I. C. S., Prescod, N., Smellie, J. M. Br. med. J. 1977, ii, 285. 14. Forbes, P. A., Drummond, K. N.J. infect. Dis. 1973, 128, (suppl), S626. 15. MacGregor, M. E., Wynne Williams, C. J. E. Lancet, 1966, i, 893 16. Shand, D. G., Nimmon, C. C., O’Grady, F., Cattell, W. R. ibid. 1970, i,

1305.

Lindberg, V., Bjure, J., Haugstvedt, S., Jodal, U. Acta pœdiat. scand. 1975, 64, 437. 18. Neumann, P. Z., de Domenico, I. J., Nogrady, M. B. Pediatrics, Springfield, 1973, 52, 241. 19. O’Grady, F., Cattell, W. R. Br. J. Urol. 1966, 38, 156. 20. Stamey, T. A., Condy, M., Milhara, G. New Engl. J. Med. 1977, 296, 780. 21. Grüneberg, R. N., Smellie, J. M., Leakey, A., Atkin, W. S. Br. med. J. 1976, 17.

ii, 206. 22. 23.

Grüneberg, R. N., Leakey, A., Bendall, M. J., Smellie, J. M. Kidney Int. 1975, 8, (suppl 4), S122. Lindberg, V., Hanson, L. A., Jodal, U., Lidin-Janson, G., Lincoln, K., Olling, S. Acta pœdiat. scand. 1975, 64, 432. J. D., Waterman, A. M., Gower, P. E., Koutsaimanis, K.G.J. med. Microbiol. 1975, 8, 311.

24. Roberts, A. P., Linton,

FACTORS INFLUENCING LACTATION PERFORMANCE IN RURAL GAMBIAN MOTHERS R. G. WHITEHEAD MELANIE HUTTON

M. G. M. ROWLAND

ELISABETH MÜLLER

ALISON PAUL

A. M. PRENTICE

Medical Research Council Dunn Nutrition Unit, Milton Road, Cambridge CB4 1XJ, and Keneba, The Gambia.

Breast-milk consumption has been measured in a rural African community in which breast-feeding on demand is universally practised until the baby is 18 mos old. The mother’s long-term capacity for breast-milk production is determined by the end of the second month of lactation, yield being closely correlated with the infant’s birth-weight. Other factors significantly influencing output were parity, month of lactation, baby’s weight-for-age, season, and maternal diet. Daily milk consumption was limited primarily by the amount delivered per feed, not the frequency of feed-

Summary

ing. THE

Introduction universal shortage of information

on

the

179 amounts of milk produced by lactating mothers at different stages of infancy and our remarkable ignorance of the factors determining the lactation capacity of different individuals is a major stumbling block for those trying to improve the nutritional status of infants. In many poor countries a considerable impairment in growth becomes evident before 6 mos,1,2 even though apparently the mother is successfully breast-feeding her

child.

Many factors can influence the establishment and maintenance of lactation, including complex sociological, psychological, and clinical determinants.3 This study, however, was carried out in a rural African village with more basic problems. Although breast-feeding is the standard practice and is continued by everyone well into the second year of life, not all women are equally effective in meeting the nutritional requirements of their child and this paper identifies some of the reasons.

Methods

village in The Gambia, where these investigations performed, has been described in detail esewhere.4,5

Keneba were

Fig. 1—Relation

between daylight intake of breast-milk and month of lactation (mean and S.D.). Number of mothers is shown.

whom The Infant Breast-milk intake was measured serially by the test-weighin 81 children aged 1-18 mos. Every effort was made to avoid disruption of normal day-to-day activities; mothers continued with their usual household and agricultural duties. Infants were supervised by their customary childminders in a compound. The children were fed on demand, the mothers being brought to the compound whenever needed. To avoid excessive demands on the mother, most of the studies were confined to daylight hours (7 A.M.-7 P.M.) but, to enable these 12 h measurements to be related to whole-day intakes, additional home studies were made on 26 of the children. Gambian nutritional assistants stayed overnight with mother and baby so that test-weighing could be continued during the remainder of the 24 h. The intake of weaning foods which are traditionally introduced as a supplement relatively early in infancy was measured by the test-weighing technique for 6 days in each month throughout the first 18 mos of life.

ing procedure

TheMother Mothers were observed regularly from as early as possible during pregnancy (usually 12-16 weeks of gestation), aJ throughout lactation. A midwife was present at the birth of the infant; accurate birth-weights were thus obtained. Food intake was measured by the test-weighing technique on 6 days each month. Measurements were made not only of food consumption within the home, but records were also made of all additional food taken, especially when mothers were working in the fields often at some distance from the village. This was achieved by having trained nutrition assistants accompany the mothers throughout the day.

Results Variation

by Month of Lactation

The relation between 12 h intakes and the age of the infant is shown in fig. 1. Breast-milk intake did not increase with age to meet the raised nutritional needs of the growing child. There was little change in mean milk intake over the first 3 mos of lactation; thereafter it fell At any given infant-age a considerable variation in output existed between mothers. In those in

progressively.

whole-day intakes were measured there was a highly significant correlation between 12 h and 24 h On this basis the estimated values (r=0.86, p