Annals of Human Biology
ISSN: 0301-4460 (Print) 1464-5033 (Online) Journal homepage: http://www.tandfonline.com/loi/iahb20
The stunted child with an overweight mother as a growing public health concern in resource-poor environments: a case study from Guatemala Colleen M. Doak, Maiza Campos Ponce, Marieke Vossenaar & Noel W. Solomons To cite this article: Colleen M. Doak, Maiza Campos Ponce, Marieke Vossenaar & Noel W. Solomons (2016): The stunted child with an overweight mother as a growing public health concern in resource-poor environments: a case study from Guatemala, Annals of Human Biology, DOI: 10.3109/03014460.2015.1136356 To link to this article: http://dx.doi.org/10.3109/03014460.2015.1136356
Published online: 10 Feb 2016.
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Article views: 9
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Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=iahb20 Download by: [Fondren Library, Rice University ]
Date: 23 February 2016, At: 04:01
http://informahealthcare.com/ahb ISSN: 0301-4460 (print), 1464-5033 (electronic) Ann Hum Biol, Early Online: 1–9 ! 2016 Taylor & Francis. DOI: 10.3109/03014460.2015.1136356
RESEARCH PAPER
The stunted child with an overweight mother as a growing public health concern in resource-poor environments: a case study from Guatemala Colleen M. Doak1, Maiza Campos Ponce1, Marieke Vossenaar2 and Noel W. Solomons2 Health Sciences, VU University, Amsterdam, The Netherlands and 2Center for Studies of Sensory Impairment, Aging and Metabolism (CeSSIAM), Guatemala City, Guatemala
Downloaded by [Fondren Library, Rice University ] at 04:01 23 February 2016
1
Abstract
Keywords
Background: Overweight and obesity are emerging at alarming rates in low income women in many countries. Guatemala has the additional burden of a high prevalence of chronic undernutrition (stunting) in children. Aim: The purpose of this paper is to explore the dual burden of infant and child (5–23 months) under-nutrition and maternal over-weight and obesity in the Western Highlands of Guatemala. Subjects and methods: Anthropometric measures were collected in 446 mother–infant dyads in a metropolitan population of mixed indigenous (Maya) and non-indigenous descent in the Western Highlands of Guatemala. Children were identified as stunted based on a height for age 52 below the WHO reference median and maternal overweight/obesity defined as a BMI 25. Stunted children with an overweight/obese mother were compared to other children who were not stunted and/or who did not have an overweight/obese mother. Results: The prevalences of stunting (38%) and maternal overweight/obesity (45%) were high, but just 17% of the mother and child pairs were dual burden. The socio-demographic characteristics of stunted children were not influenced by maternal overweight or obesity. Conclusion: Policies are needed to address under-nutrition as well as preventing obesity and obesity-related chronic disease risks of stunted children and their mothers.
Guatemala, nutritional dual burden, overweight, SCOM, stunting
Introduction Historically, human nutrition is strongly determined by the social, political, economic and even physical environment which, together, determine the quality and quantity of foods available. Related to the social, political and economic context of nutrition and infectious disease risk, low income women and children are most vulnerable to experiencing nutrition-related diseases. Economic resources and social status all relate strongly to nutritional deficiencies, infectious diseases and in more recent decades to overweight and obesity. Public health thinking on maternal weight has evolved rapidly, from the proposition by James et al. (1999) that children with acute under-nutrition (wasting) were at substantially increased risk if the mother was also underweight. In the new millennium, concern has shifted to a ‘double-burden’ of nutrition, with both under- and overweight compatible with poverty (Dubios et al., 2011; Gulliford et al., 2003; Mendez et al., 2005; Monteiro et al., 2004a). In particular, findings that early child under-nutrition can contribute to later chronic disease risks (Barker et al., 2002; Law et al., 1993) led to additional research showing low Correspondence: Dr Colleen M. Doak, Assistant Professor, Department of Health Sciences, Section of Infectious Disease, Faculteit der Aard- en Levenswetenschappen, VU University, De Boelelaan 1085-1087, 1081 HV Amsterdam, The Netherlands. Tel: +31 20 59 81754. E-mail: [email protected]
History Received 23 September 2015 Revised 15 December 2015 Accepted 16 December 2015 Published online 8 February 2016
birth weight (Ravelli et al., 1999) and child stunting (Hoffman et al., 2007) are associated with overweight and obesity. These findings contributed to research into the undernourished children co-existing in households in which the mother is, paradoxically, overweight or obese (Doak et al., 2005; Garrett & Ruel, 2005a). In this context, the current public health challenge has emerged as the ‘double-burden’ of malnutrition (Doak et al., 2005; Tanumihardjo et al., 2007) resulting in greater attention to combat malnutrition in all of its forms (Uauy & Solomons, 2005). To some, this nutrition transition was manifested in a microcosm within the family unit by a double (household) burden, an apparent paradox with an overweight mother and a child with under-weight or stunting living under the same roof. This has been quantified in numerous geographical settings (Doak et al., 2000, 2002, 2005; Garrett & Ruel, 2005a,b) including the Maya in Mexico (Azcorra et al., 2013) and in Guatemala (Lee et al., 2010, 2012). These studies demonstrate child under-nutrition can occur in a documented obesogenic environment. An obesogenic environment, together with child undernutrition, can be explained by the findings of Monteiro et al. (2004b), who identified a GNP level of $2500 and above as the level at which low income women have an increased risk of overweight and obesity. Monteiro et al. (2004b) explain obesity in low income women through the cheaper price of sugar and edible oils, resulting in a diet that is energy-dense,
Downloaded by [Fondren Library, Rice University ] at 04:01 23 February 2016
2
C. M. Doak et al.
but micronutrient-poor. Additionally, economic changes have led to mechanised labour and transport, resulting in lower physical activity (Popkin, 2004; Popkin & Gordon-Larsen, 2004). Together, these trends explain a widespread obesogenic environment that can co-exist with poverty and traditional food insecurity (Joint WHO/FAO Expert Consultation, 2003). These global trends raise new public health concerns for the under-nourished children whose mothers are overweight or obese. Guatemala is well above the $2500 per capita threshold predicting obesity risk in low income women (Monteiro et al., 2004b). Additionally, Guatemala has the highest prevalence of stunting in Latin American (Pan American Health Organization, 2008). Furthermore, Lee et al. (2010, 2012) have found stunted children with an overweight mother in a Guatemalan population. They found the stunted child and overweight mother pattern was more likely to occur in households that were rural, indigenous and low/middle income (Lee et al., 2012). More recently, Dieffenbach and Stein (2012) showed the combination of stunted child and maternal obesity can be predicted by the joint probabilities related to the prevalence of female obesity and child undernutrition at the country level. The joint clustering of stunted children and overweight or obese mothers is logical given current trends showing overweight and obesity is emerging among low-income women. The purpose of this paper is to document the stunted child/ overweight mother (household dual burden) in a Guatemalan population traversing the nutrition transition. Additionally, we explore whether risk factors for stunting in children are also associated with—or modified by—an obesogenic household environment. Finally, this study seeks to identify the dualburden dyad can be predicted by risk factors other than those associated with stunting. We have chosen to explore these questions in a metropolitan population of mixed indigenous and non-indigenous ascent in the Western Highlands of Guatemala.
Methods Subjects, setting and ethics This study was a convenience sample conducted in the highlands of Guatemala in urban Quetzaltenango and a neighbouring suburb of La Esperanza. In comparison with Quetzaltenango, the population of La Esperanza is more indigenous and lower income. The population of interest was infants and children between 5–23 months. Initially 456 mother–child dyads were selected for a study focusing on early feeding practices in relation to stunting. The oversampling of 5-month old infants (n ¼ 156) reflects the importance of the feeding practices just before the sixth month in relation to WHO breastfeeding recommendations and, related to feeding practices, risk of growth retardation. The remaining 300 dyads were selected from caretakers with infants 6–23 months of age. Caretakers (mothers) of infants and children of 5–23 months were recruited into the study while visiting local public health centres for routine checkups, vaccinations or illness. Exclusion criteria included: (1) pre-mature birth (defined as born more than 4 weeks preterm); (2) had a sibling who was already enrolled in the study;
Ann Hum Biol, Early Online: 1–9
(3) had congenital anomalies or chronic illness; and (4) were unwilling to sign the study consent form. The study recruitment period was from February to October 2011. Ethical approval was obtained from the Human Subjects Committee of the Centre for Studies of Sensory Impairment, Aging and Metabolism (CeSSIAM) and the study conforms to the provisions of the Declaration of Helsinki in 1995 (as revised in Edinburgh 2000). The study protocol was approved by the local authorities of the Ministry. The study procedures were explained and informed consent was obtained from all mothers. Data collection A structured questionnaire was administered by local, trained researchers by means of a face-to-face interview. Sociodemographic data of the mother included date-of-birth, age, marital status, number of children, highest level of schooling and current occupation. Ethnicity was determined by observation of clothing used. Child’s gender, date-of-birth and place-of-birth were queried. Anthropometric measurements were collected for the infant by trained researchers following standard procedures described by Lohman et al. (1988). Recumbent spine length was measured thrice using a SecaÕ measuring mat (model number 2101821009) to the nearest 0.5 cm. Mothers’ standing height was measured without shoes in centimetres (cm) to the nearest 0.5 cm. Mothers were weighed with a calibrated balance scale (CamryÕ model BR9709) to the nearest 0.1 kg without shoes and with minimum clothing. Data analysis Obesogenic environment The obesogenic environment was determined both at the community and individual level, using the mothers Body Mass Index (BMI) (weight in kilograms/height in metres squared). First, maternal BMI was used to classify mothers according to the World Health Organisation (WHO, 1995) criteria for overweight (BMI 25 kg/m2). The prevalence of mothers with a BMI 25 was used to identify the extent of overweight and obesity in the community as a whole. Maternal BMI was also used as a proxy for the mother’s and child’s household exposure to an obesogenic environment. Children and their mothers were identified as living in an obesogenic environment if the mothers were assessed as having a BMI of 25 kg/m2. Children in an obesogenic environment were first compared to all other children (mothers BMI 525 kg/m2). In additional sub-analysis children in an obesogenic environment were also compared to children whose mothers BMI was in the normal range (BMI between 18.5–25 kg/m2) and finally to those whose mothers were classified as underweight (BMI 518.5 kg/m2). Ageappropriate WHO definitions were used for mothers under the age of 19 years. For overweight and above, the WHO definition for overweight (BMI +1 SD above the reference median) was used, this cut-off roughly reflects the percentile equivalent to a BMI of 25 kg/m2 in 19 year old girls. Likewise, the criteria for underweight was also shifted accordingly, with the 18.5 kg/m2 cut-off used to identify underweight in adults being replaced by an age appropriate criteria of 1 SD below the reference value for 17.5 year old females.
DOI: 10.3109/03014460.2015.1136356
Child under-nutrition Child under-nutrition was assessed using the WHO criteria for chronic under-nutrition, i.e. stunting. Stunting was defined using WHO definitions as a length 2 z-scores below the median of the WHO international growth references for the child’s age in months.
Downloaded by [Fondren Library, Rice University ] at 04:01 23 February 2016
Risk factors associated with stunting Stunting was tested in relation to known characteristics of the children, such as being a boy, having had a low birth weight and being in an older age group. Low birthweight was defined as a reported birth weight 52500 g (WHO, 2002). Age of the infant was calculated based on the date-of-birth and date-ofinterview and then sub-divided into four different age groups: 5 month olds; 6–11 months, 12–17 months, and 18–23 months. The age classifications were chosen based on the sampling procedures of the study, which over-sampled for 5 month olds, and aimed for roughly equal numbers in each of the remaining age groups. In evaluating associations by age group, the 5 month olds were used as the reference. Characteristics of the mother Stunting was tested in relation to a number of risk factors related to the mother’s characteristics, including her current height as a proxy for prior stunting experience, location of residence, marital status, level of schooling, ethnicity, age and occupation. Maternal shortness was defined based on her current height, using the cut-off of a height 52 SD below the median of the WHO international references for the last value available. Thus, mothers above the age of 19 years were identified as short if they were shorter than 150.1 cm, a cut-off equivalent to 52 SD below the 2007 WHO reference median height for females of 19 years of age. Mothers below the age of 19 years were identified as stunted if their height was 52 SD below the height for age reference for 16, 17 or 18 year old females, depending on the age of the mother. Location was defined as either urban Quetzaltenango or suburban La Esperanza based on the location of the mother’s interview. Mothers who reported being divorced, widowed or single were compared to those who reported being married or united. Mother’s level of education was classified as ‘low’ for primary school and lower and as ‘high’ for secondary school and higher. The occupation of the mothers was categorised into two groups: (i) working outside the home or (ii) not working outside the home, which includes housewives. The ethnicity of the mother was determined by the clothes of the woman. If the mother was wearing a traditional dress, she was classified as Indigenous (Maya), when wearing modern clothes she was classified as Ladina. The age of the mother was calculated based on the dateof-birth and date-of-interview. The mothers were categorised into two groups according to their age, distinguishing between teenagers (19.9 years) and adults (20.0 years). Parity was categorised as having either a single child or having more than one child. Statistical methods Data were analysed with the SPSS statistical software package version 19.0 (SPSS Inc., Chicago, IL). Odds ratios and 95%
Stunted children with overweight mothers in Guatemala
3
confidence intervals were used to identify risk factors associated with stunting. Analysis was stratified for children within an obesogenic household environment (i.e. maternal overweight and obesity) and children not living in an obesogenic environment. Odds Ratios (OR) 2.0 for effect estimates were interpreted as strong associations, whether or not they met a formal significance criteria set at the p50.05 level. Risk factors were first tested in relation to stunting to identify possible confounders. Afterwards, logistic regression was used to test the association between the obesogenic environment and stunting, testing all previously identified confounders. Potential effect modifiers were tested first by stratified analysis and associations that differed by strata were tested statistically using an interaction term. The statistical criterion used to identify a statistically-significant interaction term was less strict (p50.10) than for the effect estimates (p50.05) in order to detect weaker, but potentially important, interactions. As a final analysis, the stunted child living with an overweight or obese mother (dual burden) dyads were compared to other dyad types. Each of the covariates was tested using crude ORs and 95% confidence intervals to identify whether the dual burden group differs from the other dyad types as follows: (1) the dual burden group compared to all other children (not dual burden); (2) the dual burden group compared to stunted children whose mothers have a BMI 525 kg/m2; (3) the dual burden group compared to nonstunted children whose mothers have a BMI 525 kg/m2; and (4) the dual burden group compared to children who are not stunted but whose mothers are overweight (BMI 25 kg/m2). For each risk factor tested, ORs separately tested the association between the risk factor and dual burden using each of the four reference dyads. In this way, we aim to evaluate whether there are risk factors that are specific to the dual burden dyad type or if the risk factors found for dual burden can be explained as related to the risk factors for child stunting or, alternatively, maternal BMI (25 kg/m2).
Results The initial study sample was 456 mothers and children and, of these, four children were missing data for height or age information needed to classify their stunting status. Additionally, six mothers were missing information for height and weight needed to classify their BMI status. Hence, we were able to analyse 446 infant–mother dyads, among which 171 (38.3%) infants were below the 2 HAZ criterion for stunting. Less than 5% (n ¼ 22) of the mothers 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 -
Overweight
Obese
N=446
N=171
N=275
10.8
11.1
10.5
34.3
32.7
35.3
All mothers
Mothers of stunted children
Mothers of non-stunted children
Figure 1. Maternal overweight and obesity prevalence.
4
C. M. Doak et al. 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 -
Ann Hum Biol, Early Online: 1–9
% =25) environment (BMI
ISSN: 0301-4460 (Print) 1464-5033 (Online) Journal homepage: http://www.tandfonline.com/loi/iahb20
The stunted child with an overweight mother as a growing public health concern in resource-poor environments: a case study from Guatemala Colleen M. Doak, Maiza Campos Ponce, Marieke Vossenaar & Noel W. Solomons To cite this article: Colleen M. Doak, Maiza Campos Ponce, Marieke Vossenaar & Noel W. Solomons (2016): The stunted child with an overweight mother as a growing public health concern in resource-poor environments: a case study from Guatemala, Annals of Human Biology, DOI: 10.3109/03014460.2015.1136356 To link to this article: http://dx.doi.org/10.3109/03014460.2015.1136356
Published online: 10 Feb 2016.
Submit your article to this journal
Article views: 9
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=iahb20 Download by: [Fondren Library, Rice University ]
Date: 23 February 2016, At: 04:01
http://informahealthcare.com/ahb ISSN: 0301-4460 (print), 1464-5033 (electronic) Ann Hum Biol, Early Online: 1–9 ! 2016 Taylor & Francis. DOI: 10.3109/03014460.2015.1136356
RESEARCH PAPER
The stunted child with an overweight mother as a growing public health concern in resource-poor environments: a case study from Guatemala Colleen M. Doak1, Maiza Campos Ponce1, Marieke Vossenaar2 and Noel W. Solomons2 Health Sciences, VU University, Amsterdam, The Netherlands and 2Center for Studies of Sensory Impairment, Aging and Metabolism (CeSSIAM), Guatemala City, Guatemala
Downloaded by [Fondren Library, Rice University ] at 04:01 23 February 2016
1
Abstract
Keywords
Background: Overweight and obesity are emerging at alarming rates in low income women in many countries. Guatemala has the additional burden of a high prevalence of chronic undernutrition (stunting) in children. Aim: The purpose of this paper is to explore the dual burden of infant and child (5–23 months) under-nutrition and maternal over-weight and obesity in the Western Highlands of Guatemala. Subjects and methods: Anthropometric measures were collected in 446 mother–infant dyads in a metropolitan population of mixed indigenous (Maya) and non-indigenous descent in the Western Highlands of Guatemala. Children were identified as stunted based on a height for age 52 below the WHO reference median and maternal overweight/obesity defined as a BMI 25. Stunted children with an overweight/obese mother were compared to other children who were not stunted and/or who did not have an overweight/obese mother. Results: The prevalences of stunting (38%) and maternal overweight/obesity (45%) were high, but just 17% of the mother and child pairs were dual burden. The socio-demographic characteristics of stunted children were not influenced by maternal overweight or obesity. Conclusion: Policies are needed to address under-nutrition as well as preventing obesity and obesity-related chronic disease risks of stunted children and their mothers.
Guatemala, nutritional dual burden, overweight, SCOM, stunting
Introduction Historically, human nutrition is strongly determined by the social, political, economic and even physical environment which, together, determine the quality and quantity of foods available. Related to the social, political and economic context of nutrition and infectious disease risk, low income women and children are most vulnerable to experiencing nutrition-related diseases. Economic resources and social status all relate strongly to nutritional deficiencies, infectious diseases and in more recent decades to overweight and obesity. Public health thinking on maternal weight has evolved rapidly, from the proposition by James et al. (1999) that children with acute under-nutrition (wasting) were at substantially increased risk if the mother was also underweight. In the new millennium, concern has shifted to a ‘double-burden’ of nutrition, with both under- and overweight compatible with poverty (Dubios et al., 2011; Gulliford et al., 2003; Mendez et al., 2005; Monteiro et al., 2004a). In particular, findings that early child under-nutrition can contribute to later chronic disease risks (Barker et al., 2002; Law et al., 1993) led to additional research showing low Correspondence: Dr Colleen M. Doak, Assistant Professor, Department of Health Sciences, Section of Infectious Disease, Faculteit der Aard- en Levenswetenschappen, VU University, De Boelelaan 1085-1087, 1081 HV Amsterdam, The Netherlands. Tel: +31 20 59 81754. E-mail: [email protected]
History Received 23 September 2015 Revised 15 December 2015 Accepted 16 December 2015 Published online 8 February 2016
birth weight (Ravelli et al., 1999) and child stunting (Hoffman et al., 2007) are associated with overweight and obesity. These findings contributed to research into the undernourished children co-existing in households in which the mother is, paradoxically, overweight or obese (Doak et al., 2005; Garrett & Ruel, 2005a). In this context, the current public health challenge has emerged as the ‘double-burden’ of malnutrition (Doak et al., 2005; Tanumihardjo et al., 2007) resulting in greater attention to combat malnutrition in all of its forms (Uauy & Solomons, 2005). To some, this nutrition transition was manifested in a microcosm within the family unit by a double (household) burden, an apparent paradox with an overweight mother and a child with under-weight or stunting living under the same roof. This has been quantified in numerous geographical settings (Doak et al., 2000, 2002, 2005; Garrett & Ruel, 2005a,b) including the Maya in Mexico (Azcorra et al., 2013) and in Guatemala (Lee et al., 2010, 2012). These studies demonstrate child under-nutrition can occur in a documented obesogenic environment. An obesogenic environment, together with child undernutrition, can be explained by the findings of Monteiro et al. (2004b), who identified a GNP level of $2500 and above as the level at which low income women have an increased risk of overweight and obesity. Monteiro et al. (2004b) explain obesity in low income women through the cheaper price of sugar and edible oils, resulting in a diet that is energy-dense,
Downloaded by [Fondren Library, Rice University ] at 04:01 23 February 2016
2
C. M. Doak et al.
but micronutrient-poor. Additionally, economic changes have led to mechanised labour and transport, resulting in lower physical activity (Popkin, 2004; Popkin & Gordon-Larsen, 2004). Together, these trends explain a widespread obesogenic environment that can co-exist with poverty and traditional food insecurity (Joint WHO/FAO Expert Consultation, 2003). These global trends raise new public health concerns for the under-nourished children whose mothers are overweight or obese. Guatemala is well above the $2500 per capita threshold predicting obesity risk in low income women (Monteiro et al., 2004b). Additionally, Guatemala has the highest prevalence of stunting in Latin American (Pan American Health Organization, 2008). Furthermore, Lee et al. (2010, 2012) have found stunted children with an overweight mother in a Guatemalan population. They found the stunted child and overweight mother pattern was more likely to occur in households that were rural, indigenous and low/middle income (Lee et al., 2012). More recently, Dieffenbach and Stein (2012) showed the combination of stunted child and maternal obesity can be predicted by the joint probabilities related to the prevalence of female obesity and child undernutrition at the country level. The joint clustering of stunted children and overweight or obese mothers is logical given current trends showing overweight and obesity is emerging among low-income women. The purpose of this paper is to document the stunted child/ overweight mother (household dual burden) in a Guatemalan population traversing the nutrition transition. Additionally, we explore whether risk factors for stunting in children are also associated with—or modified by—an obesogenic household environment. Finally, this study seeks to identify the dualburden dyad can be predicted by risk factors other than those associated with stunting. We have chosen to explore these questions in a metropolitan population of mixed indigenous and non-indigenous ascent in the Western Highlands of Guatemala.
Methods Subjects, setting and ethics This study was a convenience sample conducted in the highlands of Guatemala in urban Quetzaltenango and a neighbouring suburb of La Esperanza. In comparison with Quetzaltenango, the population of La Esperanza is more indigenous and lower income. The population of interest was infants and children between 5–23 months. Initially 456 mother–child dyads were selected for a study focusing on early feeding practices in relation to stunting. The oversampling of 5-month old infants (n ¼ 156) reflects the importance of the feeding practices just before the sixth month in relation to WHO breastfeeding recommendations and, related to feeding practices, risk of growth retardation. The remaining 300 dyads were selected from caretakers with infants 6–23 months of age. Caretakers (mothers) of infants and children of 5–23 months were recruited into the study while visiting local public health centres for routine checkups, vaccinations or illness. Exclusion criteria included: (1) pre-mature birth (defined as born more than 4 weeks preterm); (2) had a sibling who was already enrolled in the study;
Ann Hum Biol, Early Online: 1–9
(3) had congenital anomalies or chronic illness; and (4) were unwilling to sign the study consent form. The study recruitment period was from February to October 2011. Ethical approval was obtained from the Human Subjects Committee of the Centre for Studies of Sensory Impairment, Aging and Metabolism (CeSSIAM) and the study conforms to the provisions of the Declaration of Helsinki in 1995 (as revised in Edinburgh 2000). The study protocol was approved by the local authorities of the Ministry. The study procedures were explained and informed consent was obtained from all mothers. Data collection A structured questionnaire was administered by local, trained researchers by means of a face-to-face interview. Sociodemographic data of the mother included date-of-birth, age, marital status, number of children, highest level of schooling and current occupation. Ethnicity was determined by observation of clothing used. Child’s gender, date-of-birth and place-of-birth were queried. Anthropometric measurements were collected for the infant by trained researchers following standard procedures described by Lohman et al. (1988). Recumbent spine length was measured thrice using a SecaÕ measuring mat (model number 2101821009) to the nearest 0.5 cm. Mothers’ standing height was measured without shoes in centimetres (cm) to the nearest 0.5 cm. Mothers were weighed with a calibrated balance scale (CamryÕ model BR9709) to the nearest 0.1 kg without shoes and with minimum clothing. Data analysis Obesogenic environment The obesogenic environment was determined both at the community and individual level, using the mothers Body Mass Index (BMI) (weight in kilograms/height in metres squared). First, maternal BMI was used to classify mothers according to the World Health Organisation (WHO, 1995) criteria for overweight (BMI 25 kg/m2). The prevalence of mothers with a BMI 25 was used to identify the extent of overweight and obesity in the community as a whole. Maternal BMI was also used as a proxy for the mother’s and child’s household exposure to an obesogenic environment. Children and their mothers were identified as living in an obesogenic environment if the mothers were assessed as having a BMI of 25 kg/m2. Children in an obesogenic environment were first compared to all other children (mothers BMI 525 kg/m2). In additional sub-analysis children in an obesogenic environment were also compared to children whose mothers BMI was in the normal range (BMI between 18.5–25 kg/m2) and finally to those whose mothers were classified as underweight (BMI 518.5 kg/m2). Ageappropriate WHO definitions were used for mothers under the age of 19 years. For overweight and above, the WHO definition for overweight (BMI +1 SD above the reference median) was used, this cut-off roughly reflects the percentile equivalent to a BMI of 25 kg/m2 in 19 year old girls. Likewise, the criteria for underweight was also shifted accordingly, with the 18.5 kg/m2 cut-off used to identify underweight in adults being replaced by an age appropriate criteria of 1 SD below the reference value for 17.5 year old females.
DOI: 10.3109/03014460.2015.1136356
Child under-nutrition Child under-nutrition was assessed using the WHO criteria for chronic under-nutrition, i.e. stunting. Stunting was defined using WHO definitions as a length 2 z-scores below the median of the WHO international growth references for the child’s age in months.
Downloaded by [Fondren Library, Rice University ] at 04:01 23 February 2016
Risk factors associated with stunting Stunting was tested in relation to known characteristics of the children, such as being a boy, having had a low birth weight and being in an older age group. Low birthweight was defined as a reported birth weight 52500 g (WHO, 2002). Age of the infant was calculated based on the date-of-birth and date-ofinterview and then sub-divided into four different age groups: 5 month olds; 6–11 months, 12–17 months, and 18–23 months. The age classifications were chosen based on the sampling procedures of the study, which over-sampled for 5 month olds, and aimed for roughly equal numbers in each of the remaining age groups. In evaluating associations by age group, the 5 month olds were used as the reference. Characteristics of the mother Stunting was tested in relation to a number of risk factors related to the mother’s characteristics, including her current height as a proxy for prior stunting experience, location of residence, marital status, level of schooling, ethnicity, age and occupation. Maternal shortness was defined based on her current height, using the cut-off of a height 52 SD below the median of the WHO international references for the last value available. Thus, mothers above the age of 19 years were identified as short if they were shorter than 150.1 cm, a cut-off equivalent to 52 SD below the 2007 WHO reference median height for females of 19 years of age. Mothers below the age of 19 years were identified as stunted if their height was 52 SD below the height for age reference for 16, 17 or 18 year old females, depending on the age of the mother. Location was defined as either urban Quetzaltenango or suburban La Esperanza based on the location of the mother’s interview. Mothers who reported being divorced, widowed or single were compared to those who reported being married or united. Mother’s level of education was classified as ‘low’ for primary school and lower and as ‘high’ for secondary school and higher. The occupation of the mothers was categorised into two groups: (i) working outside the home or (ii) not working outside the home, which includes housewives. The ethnicity of the mother was determined by the clothes of the woman. If the mother was wearing a traditional dress, she was classified as Indigenous (Maya), when wearing modern clothes she was classified as Ladina. The age of the mother was calculated based on the dateof-birth and date-of-interview. The mothers were categorised into two groups according to their age, distinguishing between teenagers (19.9 years) and adults (20.0 years). Parity was categorised as having either a single child or having more than one child. Statistical methods Data were analysed with the SPSS statistical software package version 19.0 (SPSS Inc., Chicago, IL). Odds ratios and 95%
Stunted children with overweight mothers in Guatemala
3
confidence intervals were used to identify risk factors associated with stunting. Analysis was stratified for children within an obesogenic household environment (i.e. maternal overweight and obesity) and children not living in an obesogenic environment. Odds Ratios (OR) 2.0 for effect estimates were interpreted as strong associations, whether or not they met a formal significance criteria set at the p50.05 level. Risk factors were first tested in relation to stunting to identify possible confounders. Afterwards, logistic regression was used to test the association between the obesogenic environment and stunting, testing all previously identified confounders. Potential effect modifiers were tested first by stratified analysis and associations that differed by strata were tested statistically using an interaction term. The statistical criterion used to identify a statistically-significant interaction term was less strict (p50.10) than for the effect estimates (p50.05) in order to detect weaker, but potentially important, interactions. As a final analysis, the stunted child living with an overweight or obese mother (dual burden) dyads were compared to other dyad types. Each of the covariates was tested using crude ORs and 95% confidence intervals to identify whether the dual burden group differs from the other dyad types as follows: (1) the dual burden group compared to all other children (not dual burden); (2) the dual burden group compared to stunted children whose mothers have a BMI 525 kg/m2; (3) the dual burden group compared to nonstunted children whose mothers have a BMI 525 kg/m2; and (4) the dual burden group compared to children who are not stunted but whose mothers are overweight (BMI 25 kg/m2). For each risk factor tested, ORs separately tested the association between the risk factor and dual burden using each of the four reference dyads. In this way, we aim to evaluate whether there are risk factors that are specific to the dual burden dyad type or if the risk factors found for dual burden can be explained as related to the risk factors for child stunting or, alternatively, maternal BMI (25 kg/m2).
Results The initial study sample was 456 mothers and children and, of these, four children were missing data for height or age information needed to classify their stunting status. Additionally, six mothers were missing information for height and weight needed to classify their BMI status. Hence, we were able to analyse 446 infant–mother dyads, among which 171 (38.3%) infants were below the 2 HAZ criterion for stunting. Less than 5% (n ¼ 22) of the mothers 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 -
Overweight
Obese
N=446
N=171
N=275
10.8
11.1
10.5
34.3
32.7
35.3
All mothers
Mothers of stunted children
Mothers of non-stunted children
Figure 1. Maternal overweight and obesity prevalence.
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C. M. Doak et al. 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 -
Ann Hum Biol, Early Online: 1–9
% =25) environment (BMI
