If they lived in households without piped water or a toilet, Malaysian infants who did not breast-feed were five times more likely to die after 1 week of age than those who breast-fed, when other significant factors affecting infant mortality were taken into account. This is double the relative risk associated with not breast-feeding for infants born into households with toilets, whether or not they had piped water. Analogously, improvements in toilet sanitation appear to have reduced mortality twice as much among infants who did not breast-feed as among those who did. These findings, from a retrospective survey of infants born to a probability sample of 1,262 women in peninsular Malaysia, confirm the pernicious synergistic effect of poor sanitation and nonbreastfeeding that was postulated previously on theoretical grounds. Promoting and maintaining high initiation of breast-feeding is thus particularly important where poor sanitation is prevalent. Even more affluent areas should not be neglected, however, because socioeconomic improvement, including improved environmental sanitation, is often accompanied by decreased breast-feeding. Although the risk to each nonbreast-fed infant was less in those areas, infants there were less likely to breast-feed in Malaysia, and hence they made up a significant proportion of lives that could be saved by breast-feeding.
Mothers' recall data collected in Malaysia in 1976-1977 are analyzed to study correlates of mortality of 5471 infants. Respondent population is 1262 women living in 52 primary sampling units of Peninsular Malaysia. Lengths of unsupplemented and supplemented breastfeeding and presence of piped household water and toilet sanitation are related to infant mortality in regressions that also control other correlates. The analysis is disaggregated into three periods of infancy. Through six months of feeding, unsupplemented breastfeeding is more strongly associated with fewer infant deaths than is supplemented breastfeeding. Type of sanitation is generally more strongly associated with mortality than is type of water supply. The effects of breastfeeding and the environmental variables are shown to be strongly interactive and to change systematically during the course of infancy. Breastfeeding is more strongly associated with infant survival in homes without piped water or toilet sanitation. In homes with both modern facilities, supplemented breastfeeding has no significant effect, and unsupplemented breastfeeding is statistically significant only for mortality in days 8-28. Presence of modern water and sanitation systems appears unimportant for mortality of infants who are breastfed without supplementation for six months.
Analysis of mothers' recall data collected in 1976-1977 by a probability survey in Peninsular Malaysia shows an association between breastfeeding up to six months of age and improved survival of infants throughout the first year of life. Inappropriate sample selection and inadequate control of confounding can introduce large biases in these analyses. The magnitude and direction of these biases are presented. Even when these biases are dealt with, unsupplemented breastfeeding appears more beneficial than supplemented breastfeeding. The younger the infant and the longer the breastfeeding, the greater the estimated benefits in terms of deaths averted. The use of powdered infant formula did not appear to offset the detrimental effects of early weaning and supplementation. The positive relationships found in these analyses between breastfeeding and survival are not due to death precluding or terminating breastfeeding. Nor are they likely to be due to a shift away from breastfeeding because of recent illness, which was also controlled in the analyses. Nor are they likely to be due to other factors that both increase mortality risk and shorten breastfeeding; when such factors are taken into account, the beneficial effects of breastfeeding become stronger and imply that, if there had been no breastfeeding in this sample, twice as many babies would have died after the first week of life.
This paper presents evidence from the Malaysian Family Life Survey that mothers' reports of their babies' birthweights, including reports of unweighed babies' approximate size at birth, can be used to examine many biological and socioeconomic correlates of birthweight. The study uses a sample of 5583 singleton births that occurred between 1945 and 1976. In these data, the frequency distribution of birthweights and their bivariate and multivariate relationships with the biological correlates of mother's age, baby's sex, first parity and infant mortality are consistent with those found in prospective studies. A new biological correlate, mother's age at menarche, is introduced as a proxy for the mother's nutrition during childhood. Late age at menarche is associated with lower birthweight. Other results show mothers younger than 20 years and older than 35 appear to be at greater risk of bearing small babies, but the former effect is no longer important when parity is controlled. Short interbirth intervals are associated with small babies. We attempt to distinguish whether this is due to prematurity or to maternal nutritional depletion; both effects appear to be operating. Higher income appears to mitigate the pernicious effect of short interbirth intervals. Indian babies weigh significantly less than those of other ethnic groups. Furthermore, birthweights have increased since the 1950s for Malays and Chinese, but not for Indians. The lower birthweights and lack of improvement over time for Indians appear to be due to close birthspacing, lack of access to medical care and falling incomes.