Running Head: BREASTFEEDING AS PREDICTIVE OF MENTAL WELLBEING AND OBESITY AT 9-YEARS
Is breastfeeding in infancy predictive of child mental wellbeing and protective against obesity
at 9-years of age?
Authors:Deirdre Reynolds M.Psych.Sc.
Assistant Psychologist
St Michael's House Willowfield Park, Dublin 14
E-mail: [email protected] Telephone: 353 87 6714256
Eilis Hennessy1 PhD
Senior Lecturer School of Psychology
School of Psychology, Newman Building, University College Dublin, Belfield, Dublin 4,
Ireland
E-mail: [email protected] Telephone: + 353 1-7168362
Ela Polek PhD
Lecturer School of Psychology
School of Psychology, Newman Building, University College Dublin, Belfield, Dublin 4,
Ireland
E-mail: [email protected] Telephone: +353 1-7168392
Word Count: 3551
Keywords: breastfeeding, obesity, mental wellbeing, child health, infant feeding1Corresponding Author
BREASTFEEDING AS PREDICTIVE
Abstract
Background Preventing child mental health problems and child obesity have been recognised
as public health priorities. The aim of the present study was to examine whether being
breastfed (at all or exclusively) in infancy was a predictor of mental wellbeing and protective
against risk of obesity at age 9.
Methods Cross-sectional data from a large, nationally representative cohort study in the
Republic of Ireland was used (N=8357). Data on breastfeeding was retrospectively recalled.
Child mental wellbeing was assessed using a parent-completed Strengths and Difficulties
Questionnaire (SDQ). Child’s height and weight were measured using scientifically calibrated
instruments.
Results Logistic regression analyses indicated that, after controlling for a wide range of
potential confounding variables, being breastfed in infancy was associated with a 26% (p <
0.05) reduction in the risk of an abnormal SDQ score at 9-years. Being breastfed remained a
significant predictor of child mental wellbeing when child obesity was controlled for,
indicating that being breastfed, independent of child obesity, is a predictor of child mental
wellbeing. The results of a second logistic regression indicated that, after controlling for a
wide range of potential confounding variables, being breastfed for between 11 and 25 weeks
was associated with a 36% (p < 0.05) reduction in the risk of obesity at 9-years, while being
breastfed for 26 weeks or longer was associated with a 48% (p <.01) reduction in the risk of
obesity at 9-years.
Conclusions Breastfeeding in infancy may protect against both poor mental wellbeing and
obesity in childhood.
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BREASTFEEDING AS PREDICTIVE
Introduction
Between 10% and 20% of children globally have emotional or behavioural problems
(Belfer, 2008). Emotional, behavioural and mental health problems are the most common
cause of morbidity in childhood and constitute an important public health issue (Denyer et al.,
1999). Similarly, due to the many long-term adverse effects of childhood obesity, the
prevention of child obesity has been recognised as a public health priority (James et al.,
2004). Obesity is a contemporary epidemic; over the past three decades worldwide
prevalence of childhood obesity has greatly increased (Han et al., 2010). Obese children have
a greater likelihood of becoming obese adults (Power et al., 1997; Serdula et al., 1993) who
then face an increased risk of chronic diseases and premature mortality (James et al., 2004).
The primary consequence of being obese in childhood is that it negatively affects mental
wellbeing (Griffiths et al., 2011; Sjoberg et al., 2005; Warschburger, 2005). There is no single
definition of mental wellbeing. Mental wellbeing can be understood as a multidimensional
construct that encompasses emotional, psychological, social, and behavioural wellbeing (Adi
et al., 2007). Mental wellbeing contributes significantly to the quality of children’s lives.
Experiencing mental health difficulties can be associated with educational underachievement
(McClelland et al., 2000) and physical illness (Buchanan, 1999). Mental health problems are
difficult to treat; interventions designed to prevent mental health problems are much more
successful (Tennant et al., 2007). Similarly, as obesity is difficult to treat, prevention is key to
controlling this epidemic. Identifying modifiable risk and protective factors against child
mental health problems and obesity is essential. Breastfeeding has been identified as a
protective factor against both poor mental wellbeing and obesity in childhood.
To date, only four studies have examined the association between breastfeeding and
child mental wellbeing, and the findings are inconsistent. Three of the studies found that
breastfeeding was a predictor of increased child mental wellbeing (Heikkilä et al., 2011;
Julvez et al., 2007; Oddy et al., 2010) whereas the fourth (Kramer et al., 2008), found no
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evidence that prolonged and exclusive breastfeeding was a predictor of child mental
wellbeing.
Three meta-analyses have examined the association between breastfeeding and child
obesity and all three meta-analyses found a protective effect of breastfeeding against risk of
child obesity (Arenz et al., 2004; Harder et al., 2005; Owen et al., 2005). However, many
studies have not controlled for parental weight status, which may be an important
shortcoming since parental BMI has been shown to be amongst the strongest determinants of
childhood overweight (Danielzik et al., 2002; Li et al., 2009), reflecting the contribution of
shared genes and shared environment. In addition, many studies do not control for other
dietary factors that might lead to obesity, leaving open the possibility that mothers who care
about nutrition both breastfeed and feed other healthy foods later on, such that the association
of breastfeeding and obesity is confounded by dietary differences. Furthermore, high fat
foods in children’s diets may be associated with social class as it has been found that higher
parental education and family income were correlated with lower percentage of dietary fat
intake (Crawford et al., 1995).
Given the substantial evidence that child obesity negatively effects mental wellbeing
(e.g. Friedlander et al., 2003, Griffiths et al., 2011; Sjoberg et al., 2005; Warschburger, 2005),
it is possible that the significant positive association between breastfeeding and child mental
wellbeing may attenuate when child obesity is controlled for. Previous studies that examined
whether breastfeeding is a predictor of child mental wellbeing did not control for child
obesity (Heikkilä et al., 2011; Julvez et al., 2007; Kramer et al., 2008; Oddy et al., 2010). In
the present study we estimate the effects of breastfeeding in infancy on mental wellbeing and
obesity at 9-years of age.
Methodology
Participants
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The present study used cross-sectional data collected from 8568 9-year-olds
participating in the Growing Up in Ireland (GUI) study, a nationally representative cohort
study of children living in the Republic of Ireland. For a full description of the sample
method see ‘Sample Design and Response in Wave 1 of the Nine-Year Cohort of Growing Up
in Ireland’ (2010). The data were weighted prior to analysis to account for the complex
sampling design. Tables 1 and 2 present descriptive statistics for the sample. From the total
GUI sample we selected the sub-sample of children whose biological mother was the primary
caregiver (effective sample in this study was N=8357). This decision was based on the
assumption that data on retrospectively recalled breastfeeding would be more reliable if it
came from the child’s biological mother. All stages of the GUI project were subject to
rigorous ethical review by the Health Research Board’s standing Research Ethics Committee
based in Dublin. This included a review of all instrumentation, recruitment, consent, and
implementation protocols adopted.
Insert Tables 1 and 2 here
Measures
Breastfeeding measure
Information concerning breastfeeding initiation and duration was ascertained retrospectively
via parental recall. Biological mothers were asked whether the study child was ever breastfed.
Breastfeeding duration (at all or exclusively) was categorised into never breastfed, breastfed
for 10 weeks or less, breastfed for 11-25 weeks, breastfed for 26 weeks or more.
Mental health
The Strengths and Difficulties Questionnaire, SDQ (Goodman, 1997) is a brief (25-item)
behavioural screening questionnaire designed to assess emotional health and problem
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behaviours. The instrument produces scores for five subscales: Emotional symptoms,
Conduct problems, Hyperactivity/inattention, Peer relationship problems and Prosocial
behaviour. A Total Difficulties score is obtained by summing scores across the four deficit-
focused scales. Scores between 17 – 40 are interpreted as being within the abnormal range
(Cluver & Gardner 2006). The SDQ has been shown to correlate highly with the Child
Behaviour Checklist (Goodman & Scott, 1999) and has been found to have good internal
consistent reliability (Goodman, 2001) with coefficient alphas ranging from moderate (Peer
problems – 0.59) to strong (Total Difficulties – 0.82).
Measurement of obesity
During the household interview, trained interviewers assessed primary and secondary
caregivers’, as well as the study child’s height and weight using scientifically calibrated
measuring instruments. Weight measurements were recorded to the nearest 0.5 kilogram
using a SECA 761 medically approved mechanical scale. Height was recorded to the nearest
millimetre using a Leicester portable height stick. The data were screened by the GUI data
management team for biologically implausible data. Adult BMI was calculated by dividing
weight in kilograms by height in metres, squared. As children may have been interviewed at
any stage between their ninth and tenth year, the internationally acceptable obesity cut-off
point, as recommended by Cole and colleagues (2000), for children aged 9.5 years was used.
Covariates
A wide range of potential confounding factors that have been identified as being
associated with breastfeeding and mental wellbeing (Lawson & Mace, 2010; Robinson et al.,
2008; Rutter, 2005), and with breastfeeding and child obesity (Kleiser et al., 2009; Owen et
al., 2005), were controlled for. These potential confounding factors were grouped into child
characteristics, mother characteristics, and household characteristics.
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Child characteristics: gender, gestation - represented as a four level variable (late (42
weeks), on-time (37-41 weeks), somewhat early (33-36 weeks), very early (32 weeks or
less)), if the child spent time in a neonatal intensive care unit (NICU) - represented as a
dichotomous variable (yes, no), birthweight in kilograms, represented as a dichotomous
variable (2500 g, 2500 g), child obesity - represented as a dichotomous variable (obese,
not obese). Child obesity was defined as a BMI of 23 or higher (Cole et al. 2000); TV
viewing hours, which was represented as a dichotomous variable ( 3 hours, 3 hours).
Exercise over the last two weeks, which was represented as a 5 level variable (none, 1-2 days,
3-5 days, 6-8 days, 9 days). The child was asked how many times he/she had consumed: -
biscuits/doughnuts/cake/pie/chocolate, crisps/savoury snacks, chips, fizzy drinks, in the last
24 hours, which was represented as a 3 level variable (none, one serving, > one serving).
Mother characteristics: age at data collection - represented as a 3 level variable (
26, 27-49, 50), born in Ireland - represented as a dichotomous variable (yes, no), smoked
during pregnancy - represented as a dichotomous variable (yes, no), education - represented
as a dichotomous variable (degree or higher, less than a degree), current depressive
symptomatology - represented as a dichotomous variable (depressed, not depressed), which
was derived using a Center for Epidemiological Studies Depression Scale 8-item (CES-D 8)
(Radloff, 1977), a self-report screening instrument for depression based on the frequency of
depressive symptomatology during the past week. A CES-D cut-off score of 16 is indicative
of “significant” depressive symptomatology. The CES-D has been shown to be reliable with
Cronbach’s alphas ranging from .85 to .90 (Radloff, 1977). The CES-D 8 demonstrates good
reliability and validity, and has comparable accuracy to the CES-D (Boey, 1999). Marital
status - represented as a 5 level variable (married, married & separated, divorced, widowed,
never married).
Household characteristics: household income - household net income was adjusted
for household composition using the modified Organisation for Economic Co-Operation and
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Development (OECD) equivalence scale and was represented as 5 quintiles (Lowest, 2nd, 3rd,
4th, Highest). Household composition was represented as a 4 level variable (single parent 1 or
2 children, single parent 3 or more children, couple 1 or 2 children, couple 3 or more
children); secondary caregiver’s BMI.
Results
Data were analysed using PASW Statistics 18 (2010). Pairwise exclusion of missing data was
used in all analyses reported below (a default missing data treatment in SPSS). In order to test
if breastfeeding in infancy is a significant predictor of mental wellbeing at 9-years when a
range of various confounders are controlled for, direct logistic regression was performed.
From Table 3, it may be seen that duration of breastfeeding, as a four level categorical
variable, was not a significant predictor of whether a child was classified in the abnormal
range on a parent-rated SDQ at 9-years. Due to the fact that there were very low numbers of
9-year olds with abnormal SDQ scores in three of the breastfeeding duration categories (i.e.
83 were breastfed for 10 weeks or less, 59 were breastfed for between 11 and 15 weeks, and
38 were breastfed for 26 weeks or longer), it may not have been possible to detect significant
differences between these categories. Based on this reasoning, it was decided to conduct
another logistic regression to examine if being breastfed, using a dichotomous variable of
yes/no, was predictive of mental wellbeing at 9-years.
From Table 4, it may be seen that after controlling for the influence of a wide range of
variables, if a child had been breastfed, was a significant predictor of whether the child was
classified in the abnormal range on a parent-rated SDQ at 9-years of age. The OR tells us that
if a child was breastfed, compared with never having been breastfed, he/she was 26% less
likely to be classified in the abnormal range on a parent-rated SDQ at 9-years, (OR > 0.74;
CI.95 = 0.58-0.93; p <.05).
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Insert Tables 3 and 4 here
In order to explore if breastfeeding in infancy is a protective factor against risk of
obesity at 9-years, logistic regression was performed. From Table 5, it may be seen that after
controlling for a wide range of variables, being breastfed for 10 weeks or less was not a
significant predictor of whether a child was obese at 9-years, (OR > 0.97; p > 0.05). However,
the OR tells us that if a child was breastfed for between 11 and 25 weeks, compared with
never being breastfed, he/she was 36% less likely to be obese at 9-years, (OR > 0.64; CI.95 =
0.45-0.91; p <.05). The OR tells us that if a child was breastfed for 26 weeks or longer,
compared with never being breastfed, he/she was 48% less likely to be obese at 9-years, (OR
> 0.52; CI.95 = 0.34-0.81; p <.01).
Insert Table 5 here
Discussion
The aim of this study was to examine if being breastfed (at all or exclusively) was a
predictor of mental wellbeing and protective against risk of obesity at age 9. The results show
that, even after controlling for a very wide range of confounding variables, breastfeeding in
infancy is a significant predictor of mental wellbeing at 9 years of age and it is a significant
protective factor against risk of obesity at 9 years. The finding that if a child was breastfed,
compared with never having been breastfed, he/she was 26% less likely to be classified in the
abnormal range for psychological adjustment, as measured by a parent-rated SDQ, is in line
with previous studies (Heikkilä et al., 2011; Julvez et al., 2007; Oddy et al., 2010).
Julvez and colleagues (2007) found that having been breastfed for at least 12 weeks
was associated with fewer attention, hyperactivity, and behavioural problems. Similarly,
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Heikkilä and colleagues (2011) found that having been breastfed for at least 4 months was
associated with fewer behavioural problems. Oddy and colleagues (2010) concluded that
having been breastfed for less than 6 months, compared with having been breastfed for 6
months or longer, was an independent predictor of mental health problems throughout
childhood and in early adolescence. Oddy and colleagues (2010) concluded that having been
breastfed for less than 6 months, compared with having been breastfed for 6 months or
longer, was an independent predictor of mental health problems throughout childhood and in
early adolescence. In contrast to these studies, duration of breastfeeding was not found to be
a significant predictor of whether a child was classified in the abnormal range for
psychological adjustment in this study. However, this finding should be interpreted with
caution due to the low number of 9-year olds classified in the abnormal range for
psychological adjustment in three of the breastfeeding duration categories (i.e. 83 were
breastfed for 10 weeks or less, 59 were breastfed for between 11 and 15 weeks, and 38 were
breastfed for 26 weeks or longer). It may not have been possible to detect significant
differences between these categories. Kramer and colleagues (2008) also found no evidence
of benefits of prolonged breastfeeding for child behaviour. However, Kramer and
colleagues (2008) may also have had difficulty ascertaining the association between duration
of breastfeeding and child behaviour because the duration of ‘any breastfeeding’ was
relatively similar in both the control, and in the ‘exclusively breastfed’ experimental group.
Given the substantial evidence that child obesity is negatively associated with mental
wellbeing (e.g. Friedlander et al., 2003, Griffiths, et al., 2011; Warschburger, 2005), it was
thought that the significant positive association between breastfeeding and child mental
wellbeing might attenuate when child obesity was controlled for. Previous studies that
examined whether breastfeeding is a predictor of child mental wellbeing did not control for
child obesity (Heikkilä et al., 2011; Julvez et al., 2007; Kramer et al., 2008; Oddy et al.,
2010). This study found that being breastfed, independent of child obesity, was a predictor of
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child mental wellbeing. There are a number of mechanisms to explain the finding that
breastfeeding in infancy is a predictor of mental wellbeing at 9-years. Breast milk is a rich
source of fatty acids, which are involved in brain growth, neurotransmission and metabolism
(Lauritzen et al., 2001; Mortensen et al., 2002; Yehuda et al., 1999). Fatty acids and
metabolism play a critical role in mental wellbeing (Ajilore et al., 2007; Logan, 2004;
Simopoulos et al., 1999; Stevens et al., 1995). Breastfeeding mothers, in comparison with
mothers who formula-feed, display enhanced sensitivity towards their infant, which may
foster secure attachment (Britton et al., 2006; Levelli & Poli, 1998; Pilyoung et al., 2011).
Having a secure attachment has a positive influence on the child’s mental wellbeing (Crowell
& Waters, 2005). Other possible explanations for the finding that breastfeeding is predictive
of child mental wellbeing, include the probability that breastfeeding may be a proxy for a
mother’s readiness to become a parent or a proxy for a supportive family network
(Montgomery et al., 2006).
After controlling for a wide range of potential confounding variables, being breastfed
for between 11 and 25 weeks was associated with a 36% reduction in the risk of obesity at 9-
years, while being breastfed for 26 weeks or longer was associated with a 48% reduction in
the risk of obesity at 9-years. The finding that breastfeeding has a protective effect against
risk of obesity in childhood is consistent with findings from meta-analytic studies (Arenz et
al., 2004; Harder et al., 2005; Owen et al., 2005). The finding that the longer the duration of
breastfeeding, the greater the benefits it yields, is consistent with many previous studies (e.g.
Grummer-Strawn & Mei, 2004; Harder et al., 2005; McCrory & Layte, 2012), but not all (e.g.
Hediger et al., 2001; Toschke et al., 2002). There are a number of possible mechanisms to
explain the finding that breastfeeding in infancy is protective against risk of obesity at age 9.
Unlike infant formula, breast milk contains leptin and other compounds, which play a role in
satiety and are implicated in energy metabolism (Agostoni, 2005; Lawrence, 2010).
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BREASTFEEDING AS PREDICTIVE
Metabolism affects adiposity (Walker, 2001). The compositional differences between breast
milk and formula milk, which affect energy metabolism, might explain both anthropometric
and behavioural differences between breastfed and formula-fed infants with potential long-
term consequences (Agostoni, 2005). Breastfeeding also confers an advantage in food and
taste acceptance, which is important in establishing a healthy diet (Harris, 2010).
Limitations/ Strengths
The data collected for this study were observational, not experimental, and thus we
cannot tell if confounding factors both led to the breastfeeding and the outcomes at age 9.
Although data on breastfeeding were retrospectively recalled, a literature review by Li and
colleagues (2005) concluded that retrospectively reported duration of breastfeeding is
reasonably accurate. Data were not available on whether the child’s mother had experienced
any mental health problems throughout her lifetime and this was not controlled for. It has
been well documented that maternal depression at any time, but especially prenatally and
postnatally, is a risk factor for child mental wellbeing (Luoma et al., 2001). However, the
CES-D 8, a screening instrument for current depression, was used, allowing for current
maternal significant depressive symptomatology to be controlled for. This study had a
number of methodological strengths that allow a high level of confidence to be placed in the
results. A major strength is the large and representative nature of the sample, which accounts
for approximately 1/7th of all children born in Ireland between 1997 and 1998. Another
strength is that a wide range of potential confounding factors was controlled for. In addition,
scientifically calibrated measuring instruments were used to obtain height and weight
measurements from the primary and secondary caregiver and the study child. Although a
child’s primary and secondary caregivers may not be his/her biological parents, in this study
only responses from biological mothers were used. For this reason, we can be confident that
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50% of genetic influence was controlled for. The child’s secondary caregiver’s BMI was also
controlled for, reflecting the influence of environment, and possibly, further genetic influence.
Research/practical implications
The findings from this study highlight that breastfeeding in infancy may be protective
against both poor mental wellbeing and obesity in childhood, providing further argument for
the promotion of breastfeeding as the feeding method of choice for optimal development. The
findings from this study can be used by paediatricians, general practitioners and breastfeeding
lobby groups to actively encourage breastfeeding. Due to the potential importance of these
findings, it is necessary to examine the role of other potential confounding factors not
controlled for in the current study, such as, maternal mental health over her life course. Other
beneficial lines of future research would be, to examine how breast milk affects infant
metabolism and its possible long-term effects.
Acknowledgements
The Growing Up in Ireland study was funded by the Government of Ireland through
the Department of Children and Youth Affairs. The project was designed and implemented by
the joint ESRI-TCD Growing Up in Ireland Study Team.
Key messages
Breastfeeding in infancy may be protective against both poor mental wellbeing and
obesity in childhood.
Being breastfed in infancy, independent of child obesity, may be a predictor of child
mental wellbeing.
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20
Table 1. Characteristics of the children in the sample
Variable Prevalence (%)
Breastfed Status Never breastfedBreastfed 10 wks or lessBreastfed 11-25 wksBreastfed 26 wks or more
55.418.715.510.3
Gestation Late 42 wksOn time (37-41 wks)Early (33-36)V.early ( 32 wks)
25.166.211.9 1.8
Birthweight <2500 g2500 g
5.994.1
Child BMI M 17.95SD 3.06ObeseNot obese
6.693.4
Parent-rated child SDQ score M 7.98SD 5.31Abnormal rangeNormal range
7.1 92.9
Gender MaleFemale
49.750.3
Spent time in NICU YesNo
14.285.8
Fizzy drinks in last 24 hrs NoneOne servingMore than one serving
55.733.211.1
Biscuits/doughnuts/cake/pie/chocolate in last 24 hrs
NoneOne servingMore than one serving
27.354.917.8
Crisps/savoury snacks in last24 hrs
NoneOne servingMore than one serving
44.945.6 9.4
Chips in last 24 hrs NoneOne servingMore than one serving
66.530.9 2.6
Hrs spent watching TV/DVDs in last 24 hrs
More than 3 hoursLess than 3 hours
10.789.2
Exercise over last 2 wks None1-2 days3-5 days6-8 days 9 days
2.5 5.818.019.454.4
Note. M = mean. SD = standard deviation
Table 2. Mother and household characteristics
Variable Prevalence (%)
If born in Ireland YesNo
84.115.9
Education None or primaryLower secondaryUpper secondaryNon degreeDegree Postgrad
6.423.836.715.911.2 6.0
Marital status Married & living with spouseMarried & separatedDivorcedWidowedNever married
76.9 6.5 2.1 1.113.4
Smoked during pregnancy YesNo
28.171.9
Age at data collection M 39SD 5.68 2627-49 50
24.572.4 3.2
Depressive symptomatology YesNo
1.798.3
BMI UnderweightHealthyOverweightObese
1.046.329.418.1
Secondary caregiver BMI UnderweightHealthyOverweightObese
0.122.250.127.6
Household income(net income was adjusted for
household composition using the modified OECD equivalence scale and was represented as 5 quintiles)
Highest2nd
3rd
4th
Lowest
20.020.120.119.920.0
Household composition Single parent 1 or 2 childrenSingle parent 3 childrenCouple 1 or 2 childrenCouple 3 children
7.93.738.550.0
Note. M = mean. SD = standard deviation
Table 3. Logistic regression reporting the association between duration of breastfeeding and an abnormal SDQ after control for potential confounders (n = 6752)
Child Characteristics Sig. OR 95% CIBreastfed duration(Ref cat: never)
.071
10 weeks or less .017 0.69 (0.51-0.94)11-25 weeks .122 0.76 (0.53-1.08)26 weeks or more .380 0.83 (0.56-1.25)Gestation (Ref cat: Late 42 wks) .158On time (37-41 wks) .889 1.02 (0.79-1.31)Somewhat early (33-36) .151 1.31 (0.91-1.91)V.early ( 32 wks) .044 2.06 (1.03-4.19)Birthweight ( 2500g) .743 1.09 (0.65-1.82)If child is obese .000 2.07 (1.50-2.87)Gender (if male) .006 1.35 (1.09-1.66)NICU .313 1.18 (0.86-1.63)Mother CharacteristicsIf Born in Ireland .633 1.08 (0.79-1.48)Education (degree or higher) .044 1.49 (1.01-2.19)Marital status(Ref cat: Married & living with spouse)
.000
Married & separated .005 2.22 (1.28-3.86)Divorced .087 1.69 (0.78-3.67)Widowed .000 8.16 (3.38-19.70)Never married .608 1.11 (0.74-1.68)Smoked during pregnancy .000 1.74 (1.39-2.17)Age (Ref cat: 26) .00127-49 .000 0.64 (0.51-0.82) 50 .817 1.09 (0.53-2.24)Depressive symptomatology .001 2.43 (1.42-4.16)Household CharacteristicsHousehold income (Ref cat: Highest) .0004th .110 1.39 (0.93-2.08)3rd .041 1.51 (1.02-2.24)2nd .032 1.55 (1.04-2.30)Lowest .000 2.42 (1.64-3.59)Household composition(Ref cat: single parent 1 or 2 children)
.143
Single parent 3 children .212 0.74 (0.46-1.19)
Couple 1 or 2 children .272 1.31 (0.81-2.15)Couple 3 children .133 1.45 (0.91-2.38)Ref cat = Reference category
Table 4. Logistic regression reporting the association between breastfeeding as a dichotomous variable and an abnormal SDQ after control for potential confounders (n = 6752)Child Characteristics Sig. OR 95% CIBreastfed .011 0.74 (0.58-0.93)Gestation (Ref cat: Late 42 wks) .156On time (37-41 wks) .869 1.02 (0.80-1.31)Somewhat early (33-36) .150 1.31 (0.91-1.91)V.early ( 32 wks) .042 2.07 (1.03-4.19)Birthweight ( 2500g) .743 1.09 (0.65-1.82)If child is obese .000 2.06 (1.49-2.85)Gender (if male) .006 1.34 (1.09-1.66)NICU .577 1.18 (0.85-1.62)Mother CharacteristicsIf Born in Ireland .706 1.06 (0.78-1.45)Education (degree or higher) .050 1.47 (1.00-2.16)Marital status(Ref cat: Married & living with spouse)
.000
Married & separated .004 2.24 (1.29-3.89)Divorced .177 1.71 (0.79-3.71)Widowed .000 8.18 (3.39-19.76)Never married .584 1.12 (0.74-1.69)Smoked during pregnancy .000 1.73 (1.38-2.16)Age (Ref cat: 26) .00127-49 .000 0.65 (0.51-0.83) 50 .796 1.10 (0.51-2.26)Depressive symptomatology .001 2.43 (1.42-4.15)Household CharacteristicsHousehold income (Ref cat: Highest) .0004th .110 1.39 (0.93-2.07)3rd .042 1.51 (1.02-2.23)2nd .032 1.55 (1.04-2.31)Lowest .000 2.42 (1.64-3.59)Household composition(Ref cat: single parent 1 or 2 children)
.137
Single parent 3 children .225 0.74 (0.46-1.20)
Couple 1 or 2 children .258 1.32 (0.81-2.15)Couple 3 children .120 1.47 (0.91-2.38)Ref cat = Reference category
Table 5. Logistic regression reporting the association between breastfeeding duration obesity after control for potential confounders (n = 7308)
Child Characteristics Sig. OR 95% CIBreastfed duration(Ref cat: never)
.004
Less than 10 weeks .833 0.97 (0.75-1.26)11-25 weeks .013 0.64 (0.45-0.91)26 weeks or more .003 0.52 (0.34-0.81)Gender (if male) .004 0.74 (0.61-0.91)NICU .804 1.04 (0.77-1.41)Birthweight ( 2500g) .102 1.49 (0.92-2.41)Gestation Period(Ref cat: Late 42 wks)
.038
On time (37-41 wks) .343 0.72 (0.36-1.42)Early (33-36) .105 0.58 (0.30-1.12)V.early ( 32 wks) .045 0.52 (0.27-0.99)Fizzy drinks daily .873 1.03 (0.75-1.40)Biscuits daily .351 0.88 (0.67-1.40)Crisps daily .032 0.65 (0.43-0.96)Chips daily .186 0.57 (0.25-1.31)Watches 3 hrs TV .095 1.20 (0.97-1.48)Exercise over the last 2 wks ( Ref cat: None)
.000
1 to 2 days .224 0.72 (0.48-1.22)3 to 5 days .004 0.50 (0.31-0.80)6 to 8 days .000 0.37 (0.23-0.60) 9 days) .000 0.25 (0.16-0.40)Mother CharacteristicsAge (Ref cat: 26) .33827-49 .646 0.95 (0.76-1.19) 50 .210 1.53 (0.79-2.96)Born in Ireland .126 0.81 (0.61-1.06)Smoked during pregnancy .013 1.32 (1.06-1.63)Education (degree or higher) .003 1.79 (1.22-2.62)Mother’s BMI .000 2.77 (2.24-3.43)Household CharacteristicsHousehold income (Ref cat: Highest) .5594th .180 1.27 (0.90-1.80)3rd .383 1.17 (0.82-1.66)2nd .239 1.24 (0.87-1.76)Lowest .073 1.39 (0.97-1.99)Household composition(Ref cat: Single parent 1 or 2 children)
.001
Single parent 3 children .413 1.20 (0.77-1.87)
Couple 1 or 2 children .755 0.95 (0.67-1.34)Couple 3 children .016 0.66 (0.47-0.92)Secondary caregiver’s BMI .000 2.14 (1.71-2.67)Ref cat = Reference category