- Email: [email protected]
Mechanisms linking parental education and stunting
Comment
9 10
11
Lip GY. Preventing stroke in atrial fibrillation: the SPORTIF programme. Pathophysiol Haemost Thromb 2005; 34 (suppl 1): 25–30. Snapinn S, Jiang Q. Preservation of effect and the regulatory approval of new treatments on the basis of non-inferiority trials. Stat Med 2008; 27: 382–91. Ansell J, Hirsh J, Poller L, Bussey H, Jacobson A, Hylek E. The pharmacology and management of the vitamin K antagonists: the Seventh ACCP
12
Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004; 126 (suppl 3): 204–33. Singer DE, Albers GW, Dalen JE, Go AS, Halperin JL, Manning WJ. Antithrombotic therapy in atrial fibrillation: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004; 126 (suppl 3): 429–56.
Mechanisms linking parental education and stunting See Articles page 322
Growth failure resulting from poor nutrition (stunting) is a major risk factor for deficits in children’s development.1 In addition to confirming previous findings on mothers’ education and stunting in their children,2 the results from Richard Semba and colleagues, in today’s Lancet,3 show that level of education in the father can also contribute to the risk of stunting. However, far less is known about the mechanisms (mediators) through which maternal—and now, with Semba’s results, paternal— education influences physical growth in children. Semba and colleagues suggest that increased use of health-promoting activities by educated parents (eg, vaccination and vitamin supplementation of offspring) is one mechanism through which parental education influences their child’s physical growth. Similar findings from other studies in developing countries indicate that higher levels of maternal education are related to mothers’ increased health knowledge,2 understanding of health information,4 and use of health services.5 Semba’s study also highlights an important methodological
Panos Pictures
The printed journal includes an image merely for illustration
Health and nutrition worker teaching village women in Bangladesh
280
issue, namely that association of parental education with a specific risk or protective factor does not mean that factor functions as a mediator. Appropriate statistical tests are needed to confirm that mediation is occurring.6 Studies from developing countries have identified other mechanisms that could also mediate associations between mothers’ level of education and the physical growth of their children. One potential pathway involves the association between increased maternal education and greater input by the mother into decisions on allocation of family resources.7 Because mothers are more likely than fathers to allocate family resources in ways that promote their child’s nutrition,8 education might increase the mother’s decision-making power, which improves the child’s nutrition and health and ultimately their physical growth. Other studies from developing countries have identified specific maternal factors that can also function as mediators. One such factor is maternal depression. In developing countries, more educated women are at lower risk for depression than are less educated women,9 and infants of mothers with depression are at greater risk of growth failure than are infants whose mothers are not depressed.10 The mechanism through which depression in the mother influences the physical growth of their child probably involves reduced involvement in parental care by depressed women.10 A second characteristic is the mother’s intelligence. Increased levels of schooling are linked to higher levels of maternal intelligence,11 and children of mothers who are more intelligent have better physical growth than those of less intelligent mothers.12 Because intelligence is a marker for adaptive behaviour,13 women with lower levels of intelligence might have greater difficulty making appropriate decisions on resource allocation (eg, what foods to purchase) than those with higher intelligence, when the family’s economic resources are limited. www.thelancet.com Vol 371 January 26, 2008
Comment
To facilitate understanding of mechanisms that mediate the association between parental education and physical growth of children, two crucial issues need to be addressed. First, Semba and colleagues’ results highlight the importance of identifying factors that mediate the influence of paternal education, and we cannot assume that the same mediators will hold for mothers and fathers.8 Second, there is evidence that mediators of the association between parental education and children’s growth do not function in isolation from each other, but are interlinked. For example, women who have some degree of control over family-resource allocation, or women living in families with more economic resources are at lower risk for depression than women without control over resource allocation or women living in poorer families.14 Even more crucially, the effect of a given mediator may vary as a function of the operation of other mediators. For example, the relation between maternal education and the mother’s decision-making power on household expenditures will vary as a function of the overall level of family resources,15 while the risk of growth failure for children of depressed mothers varies as a function of level of maternal intelligence.12 These findings mean that we should study what influences a child’s physical growth within a multidimensional systems framework,16,17 where the effect of one mediator depends on those of other mediators. This complexity is needed because, in the real world, mediators rarely act alone.
I declare that I have no conflict of interest. 1
2
3
4 5
6
7
8
9
10
11
12
13 14
15 16
Theodore D Wachs Department of Psychological Sciences, Purdue University, West Lafayette, IN 47907, USA [email protected]
17
Walker SP, Wachs TD, Meeks Gardner J, for the International Child Development Steering Group. Child development: risk factors for adverse outcomes in developing countries. Lancet 2007; 369: 145–57. Boyle M, Racine Y, Georgiades K, et al. The influence of economic development level, household wealth and maternal education on child health in the developing world. Soc Sci Med 2006; 63: 2242–54. Semba RD, de Pee S, Sun K, Sari M, Ahkter N, Bloem MW. Effect of parental formal education on risk of child stunting in Indonesia and Bangladesh: a cross-sectional study. Lancet 2008; 371: 322–28. Glewwe P. Why does mother’s schooling raise child health in developing countries? Evidence from Morocco. J Hum Resour 1999; 34: 124–59. Pongou R, Ezzati M, Salomon J. Household and community socioeconomic and environmental determinants of child nutritional status in Cameroon. BMC Public Health 2006; 6: 98. MacKinnon D, Lockwood C, Hoffman J, West S, Sheete V. A comparison of methods to test mediation and other intervening variable effects. Psychol Methods 2002; 7: 83–104. Becker S, Fonseca-Becker F, Schenck-Yglesias C. Husbands’ and wives’ reports of women’s decision-making power in Western Guatemala and their effects on preventive health behaviors. Soc Sci Med 2006; 62: 2313–26. Pfeiffer J, Gloyd S, Ramirez Li L. Intrahousehold resource allocation and child growth in Mozambique: an ethnographic case-control study. Soc Sci Med 2001; 53: 83–97. Patel V, Rodrigues M, DeSouza N. Gender, poverty, and postnatal depression: a study of mothers in Goa, India. Am J Psychiat 2002; 159: 43–47. Rahman A, Iqbal Z, Bunn J, Lovel H, Harrington R. Impact of maternal depression on infant nutritional status and illness. Arch Gen Psychiat 2004; 61: 946–52. Wachs TD, McCabe G, Yunis F, et al. Cognitive performance of Egyptian adults as a function of nutritional intake and sociodemographic factors. Intelligence 1996; 22: 129–54. Anoop S, Saravanan B, Joseph A, Cherian A, Jacob K. Maternal depression and low maternal intelligence as risk factors for malnutrition in children: a community based case-control study from South India. Arch Dis Child 2004; 89: 325–29. Gottfredson L. Why g matters: the complexity of everyday life. Intelligence 1997; 24: 79–132. Rahman A, Iqbal Z, Harrington R. Life events, social support and depression in childbirth: Perspectives from a rural community in the developing world. Psychol Med 2003; 33: 1161–67. Kusago T, Barham B. Preference heterogeneity, power, and intrahousehold decision-making in rural Malaysia. World Dev 2001; 29: 1237–56. Wachs TD. Multiple influences on children’s nutritional deficiencies: a systems perspective. Physiol Behav (in press). Evans G, Lepore S. Moderating and mediating processes in environment-behavior research. In: Moore G, Marans R, eds. Advances in environment, behavior and design. New York, USA: Plenum Press, 1997: 255–85.
CONSORT for reporting randomised trials in journal and conference abstracts In 2006, Arthur Amman, President of Global Strategies for HIV Prevention, made a disquieting remark: “I recently met a physician from southern Africa, engaged in perinatal HIV prevention, whose primary access to information was abstracts posted on the internet. Based on a single abstract, they had altered their perinatal HIV prevention program from an effective therapy to one www.thelancet.com Vol 371 January 26, 2008
with lesser efficacy. Had they read the full text article they would have undoubtedly realized that the study results were based on short-term follow-up, a small pivotal group, incomplete data, and unlikely to be applicable to their country situation. Their decision to alter treatment based solely on the abstract’s conclusions may have resulted in increased perinatal HIV transmission.”1
Published Online January 22, 2008 DOI:10.1016/S01406736(07)61835-2
281
9 10
11
Lip GY. Preventing stroke in atrial fibrillation: the SPORTIF programme. Pathophysiol Haemost Thromb 2005; 34 (suppl 1): 25–30. Snapinn S, Jiang Q. Preservation of effect and the regulatory approval of new treatments on the basis of non-inferiority trials. Stat Med 2008; 27: 382–91. Ansell J, Hirsh J, Poller L, Bussey H, Jacobson A, Hylek E. The pharmacology and management of the vitamin K antagonists: the Seventh ACCP
12
Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004; 126 (suppl 3): 204–33. Singer DE, Albers GW, Dalen JE, Go AS, Halperin JL, Manning WJ. Antithrombotic therapy in atrial fibrillation: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004; 126 (suppl 3): 429–56.
Mechanisms linking parental education and stunting See Articles page 322
Growth failure resulting from poor nutrition (stunting) is a major risk factor for deficits in children’s development.1 In addition to confirming previous findings on mothers’ education and stunting in their children,2 the results from Richard Semba and colleagues, in today’s Lancet,3 show that level of education in the father can also contribute to the risk of stunting. However, far less is known about the mechanisms (mediators) through which maternal—and now, with Semba’s results, paternal— education influences physical growth in children. Semba and colleagues suggest that increased use of health-promoting activities by educated parents (eg, vaccination and vitamin supplementation of offspring) is one mechanism through which parental education influences their child’s physical growth. Similar findings from other studies in developing countries indicate that higher levels of maternal education are related to mothers’ increased health knowledge,2 understanding of health information,4 and use of health services.5 Semba’s study also highlights an important methodological
Panos Pictures
The printed journal includes an image merely for illustration
Health and nutrition worker teaching village women in Bangladesh
280
issue, namely that association of parental education with a specific risk or protective factor does not mean that factor functions as a mediator. Appropriate statistical tests are needed to confirm that mediation is occurring.6 Studies from developing countries have identified other mechanisms that could also mediate associations between mothers’ level of education and the physical growth of their children. One potential pathway involves the association between increased maternal education and greater input by the mother into decisions on allocation of family resources.7 Because mothers are more likely than fathers to allocate family resources in ways that promote their child’s nutrition,8 education might increase the mother’s decision-making power, which improves the child’s nutrition and health and ultimately their physical growth. Other studies from developing countries have identified specific maternal factors that can also function as mediators. One such factor is maternal depression. In developing countries, more educated women are at lower risk for depression than are less educated women,9 and infants of mothers with depression are at greater risk of growth failure than are infants whose mothers are not depressed.10 The mechanism through which depression in the mother influences the physical growth of their child probably involves reduced involvement in parental care by depressed women.10 A second characteristic is the mother’s intelligence. Increased levels of schooling are linked to higher levels of maternal intelligence,11 and children of mothers who are more intelligent have better physical growth than those of less intelligent mothers.12 Because intelligence is a marker for adaptive behaviour,13 women with lower levels of intelligence might have greater difficulty making appropriate decisions on resource allocation (eg, what foods to purchase) than those with higher intelligence, when the family’s economic resources are limited. www.thelancet.com Vol 371 January 26, 2008
Comment
To facilitate understanding of mechanisms that mediate the association between parental education and physical growth of children, two crucial issues need to be addressed. First, Semba and colleagues’ results highlight the importance of identifying factors that mediate the influence of paternal education, and we cannot assume that the same mediators will hold for mothers and fathers.8 Second, there is evidence that mediators of the association between parental education and children’s growth do not function in isolation from each other, but are interlinked. For example, women who have some degree of control over family-resource allocation, or women living in families with more economic resources are at lower risk for depression than women without control over resource allocation or women living in poorer families.14 Even more crucially, the effect of a given mediator may vary as a function of the operation of other mediators. For example, the relation between maternal education and the mother’s decision-making power on household expenditures will vary as a function of the overall level of family resources,15 while the risk of growth failure for children of depressed mothers varies as a function of level of maternal intelligence.12 These findings mean that we should study what influences a child’s physical growth within a multidimensional systems framework,16,17 where the effect of one mediator depends on those of other mediators. This complexity is needed because, in the real world, mediators rarely act alone.
I declare that I have no conflict of interest. 1
2
3
4 5
6
7
8
9
10
11
12
13 14
15 16
Theodore D Wachs Department of Psychological Sciences, Purdue University, West Lafayette, IN 47907, USA [email protected]
17
Walker SP, Wachs TD, Meeks Gardner J, for the International Child Development Steering Group. Child development: risk factors for adverse outcomes in developing countries. Lancet 2007; 369: 145–57. Boyle M, Racine Y, Georgiades K, et al. The influence of economic development level, household wealth and maternal education on child health in the developing world. Soc Sci Med 2006; 63: 2242–54. Semba RD, de Pee S, Sun K, Sari M, Ahkter N, Bloem MW. Effect of parental formal education on risk of child stunting in Indonesia and Bangladesh: a cross-sectional study. Lancet 2008; 371: 322–28. Glewwe P. Why does mother’s schooling raise child health in developing countries? Evidence from Morocco. J Hum Resour 1999; 34: 124–59. Pongou R, Ezzati M, Salomon J. Household and community socioeconomic and environmental determinants of child nutritional status in Cameroon. BMC Public Health 2006; 6: 98. MacKinnon D, Lockwood C, Hoffman J, West S, Sheete V. A comparison of methods to test mediation and other intervening variable effects. Psychol Methods 2002; 7: 83–104. Becker S, Fonseca-Becker F, Schenck-Yglesias C. Husbands’ and wives’ reports of women’s decision-making power in Western Guatemala and their effects on preventive health behaviors. Soc Sci Med 2006; 62: 2313–26. Pfeiffer J, Gloyd S, Ramirez Li L. Intrahousehold resource allocation and child growth in Mozambique: an ethnographic case-control study. Soc Sci Med 2001; 53: 83–97. Patel V, Rodrigues M, DeSouza N. Gender, poverty, and postnatal depression: a study of mothers in Goa, India. Am J Psychiat 2002; 159: 43–47. Rahman A, Iqbal Z, Bunn J, Lovel H, Harrington R. Impact of maternal depression on infant nutritional status and illness. Arch Gen Psychiat 2004; 61: 946–52. Wachs TD, McCabe G, Yunis F, et al. Cognitive performance of Egyptian adults as a function of nutritional intake and sociodemographic factors. Intelligence 1996; 22: 129–54. Anoop S, Saravanan B, Joseph A, Cherian A, Jacob K. Maternal depression and low maternal intelligence as risk factors for malnutrition in children: a community based case-control study from South India. Arch Dis Child 2004; 89: 325–29. Gottfredson L. Why g matters: the complexity of everyday life. Intelligence 1997; 24: 79–132. Rahman A, Iqbal Z, Harrington R. Life events, social support and depression in childbirth: Perspectives from a rural community in the developing world. Psychol Med 2003; 33: 1161–67. Kusago T, Barham B. Preference heterogeneity, power, and intrahousehold decision-making in rural Malaysia. World Dev 2001; 29: 1237–56. Wachs TD. Multiple influences on children’s nutritional deficiencies: a systems perspective. Physiol Behav (in press). Evans G, Lepore S. Moderating and mediating processes in environment-behavior research. In: Moore G, Marans R, eds. Advances in environment, behavior and design. New York, USA: Plenum Press, 1997: 255–85.
CONSORT for reporting randomised trials in journal and conference abstracts In 2006, Arthur Amman, President of Global Strategies for HIV Prevention, made a disquieting remark: “I recently met a physician from southern Africa, engaged in perinatal HIV prevention, whose primary access to information was abstracts posted on the internet. Based on a single abstract, they had altered their perinatal HIV prevention program from an effective therapy to one www.thelancet.com Vol 371 January 26, 2008
with lesser efficacy. Had they read the full text article they would have undoubtedly realized that the study results were based on short-term follow-up, a small pivotal group, incomplete data, and unlikely to be applicable to their country situation. Their decision to alter treatment based solely on the abstract’s conclusions may have resulted in increased perinatal HIV transmission.”1
Published Online January 22, 2008 DOI:10.1016/S01406736(07)61835-2
281