The Relationship between Birth Order, Obesity, and Bariatric Surgery: Preliminary Data Analysis

| December 17, 2009 | 0 Comments

by Sabrina Krum, MS; Cynthia Alexander, PsyD; and
Craig Marker, PhD

Ms. Krum is completing her doctoral work at Nova Southeastern University. Dr. Marker is a professor at Nova Southeastern University and the University of Miami. Dr. Alexander, is a psychologist with the Bariatric and Metabolic Institute at Cleveland Clinic Florida, Weston, Florida.

Bariatric Times. 2009;6(12):8–10

Background: This study examines the effect of birth order in a family of four or more on obesity and how birth order may relate to those pursuing bariatric surgery. Methods: Preliminary data analysis was performed on patients who requested bariatric surgery from a hospital in South Florida. Patients who identified that they came from families with four or more children during routine interviews with the staff psychologist during presurgery evaluation were selected. Patients who came from blended families or who were adopted were not included in the study. A total of 82 patients were selected from a database of individuals requesting bariatric surgery for the study. Results: Sixty-three percent of the patients selected for the study were either the oldest or youngest in a family of four or more. A chi-square analysis was conducted, which indicated there was a significant relationship between birth order and the likelihood of opting for bariatric surgery. Conclusion: The results from this study suggest that the oldest or youngest individual in a family of four or more is more likely to pursue bariatric surgery to manage his or her weight. Parenting style, parental resources, and personality factors all may influence the prevalence of obesity and the likelihood of choosing bariatric surgery as a treatment option.

Obesity is a well-documented problem in the United States, with an upsurge in recent years in the numbers of obese individuals. The obesity rate has almost doubled between 1980 and 2004, with approximately 34 percent of adults in the obesity category.[1] Research often cites risk factors such as genetic, metabolic, environmental, and behavioral, which contribute to the problem.[2] Family factors often influence the prevalence of obesity, as children with obese parents will be more likely to be obese as well.[3] However, there is minimal research, especially in the United States, regarding birth order and family size as a potential risk factor.Studies completed in other countries have variable results concerning this topic. The research does not examine the number of siblings or whether one is the oldest or youngest in the family as factors in the risk for becoming obese.

Research often focuses on smaller family sizes when examining the risk for obesity. For example, Koziel and Kolodziej[4] conducted a study in Poland and found that first-born girls in a family of three siblings are at a higher risk for becoming obese.[4] They also found that girls further down in birth order were also more likely to become obese. There was not enough data for larger sibling groups (more than three siblings) to be considered for this study. In a similar study with African-American participants, a first-born child had a higher risk of becoming obese, but the study did not report the number of siblings in a family.[5] In another comparable study conducted in Japan, the results indicated that boys from families of four or more children, boys with no siblings, and boys from two-child families had a greater risk of obesity.[6] This study also examined sibling size in regard to the gender of other siblings. They found that boys with male and female siblings in a family of four or more had an increased risk for becoming obese in comparison with three-child families. In girls, those who were last born in the family with male and female siblings had a higher risk of obesity when compared to the middle-born girls.

A child is more likely to be obese if there are obese family members, and he or she is also more likely to remain obese into adulthood.[7] If one or both parents are obese, the risk for obesity increases in children.[3] There is a lower probability that an adult with obesity will be able to lose and maintain weight loss if he or she has been heavy since childhood.[7] This may lead to more extreme measures to regain control of his or her weight, such as pursuing bariatric surgery. In the present study, the relation of birth order in a family of four or more children was investigated in patients pursuing bariatric surgery. This investigation was prompted by the number of patients volunteering information that they were the oldest or youngest sibling in their family, while in an interview with the staff psychologist.

Subjects. Subjects for the analysis were drawn from a database of patients requesting bariatric surgery from a hospital in South Florida. The participants were first screened by the surgeon to ensure that they were good candidates for the surgery. In order to be considered for bariatric surgery, a patient needs to have a body mass index (BMI) above 35, with two additional comorbidities associated with the weight, or have a BMI above 40. The participants spent approximately 75 minutes in an interview with the staff clinical psychologist to gather information about their background, physical and mental health issues, and motivation to have bariatric surgery. Over a six-month time period an additional question specifically asking about family size and birth order was added to the assessment. One-hundred and thirty four charts that had four or more children in the family were identified; however, 52 of those patients came from blended families or were adopted and were not used in the study. In total, 82 charts of patients that came from a family of four or more children were identified and examined. Twenty of the patients were men and 62 of the patients were women. The sibling cohorts ranged from four to 18 children in a family.

Results. Fifty-two of the total 82 participants (63%) were the oldest or youngest in a family of four or more. Thirty of the 82 participants (37%) were the middle children in a family of four or more (Table 1). Twenty of the participants were men (24%) and 62 were women (76%). Twenty seven of the 82 participants (33%) came from a family of four children, while 20 participants had five children in their family (24%) (Table 2). One participant had 18 children in his family. To assess the likelihood that the oldest or youngest in a family with four or more children would choose bariatric surgery, a chi-squared analysis was used. There is a decreasing probability (less than 50%) with each additional sibling in a family of four children or more that the oldest or youngest would be overweight and pursue bariatric surgery. The likelihood that the oldest or youngest in the family is seeking bariatric surgery decreases as family size continues to increase. Results of the chi-squared test indicate that there is a significant difference between oldest/youngest and the middle children, chi-square=110.63 (10), p<0.05. The results suggest that birth order in a family of four or more is related to the risk of obesity and the likelihood of choosing to undergo bariatric surgery in order to deal with the problem.

In the current study, birth order showed a significant relationship with the frequency of obesity in the patients who were the oldest or youngest in a family of four or more and the likelihood to pursue surgery in order to manage their weight. However, further examination needs to be done in order to provide more evidence to support this data, as this finding has been reported inconsistently in research. Our results add to the current literature regarding the possible risk factor for obesity. To help us understand why there was a significance in our results, a literature review was completed.

Parental supervision and modeling. The significance of our results may be explained numerous ways by examination of existing research. Lack of parental resources may increase the likelihood of becoming obese.[4] For example, as family size grows with each child, the economic situation and resources within the family may decline, leaving fewer resources for proper nutrition. This may greatly affect lower income families, as prices for food and resources tend to be higher in lower income neighborhoods, making it more difficult for families to afford healthy food.[8] There may be decreasing parental supervision with each later-born child as family size increases.[4,7] The parent may have less time to monitor the children and what they may or may not be eating.

Since children tend to model their behavior after their parents, it is possible that if the parents have unhealthy eating habits, the children will develop their own poor-eating practices. Food preferences are often formed in childhood from what is stored in the home and from what others in the family eat.[7] This suggests that familiarity accounts for a significant portion of one’s preference, and that a child will develop a preference to eat what is unhealthy if that is what is found in the home.[7] If the parent is obese and has poor eating habits, this may increase the child’s risk of obesity due to modeling the parent’s behaviors.[3] Interestingly, children who have at least one parent with obesity are more likely to have a preference for higher-fat foods.[9] Furthermore, if the oldest sibling is obese, the younger siblings may model their eating and exercise habits after that of their older sibling.[7] The oldest sibling may act as a role model for his or her younger siblings, setting an example that they may follow.[10] Therefore, if a child grows up in a larger family where the oldest sibling is seen more as a parent, the older sibling may have a large influence over eating habits of his or her younger siblings.

Parenting style. Research shows that parenting style may also influence the likelihood of obesity in children. Research shows that permissive and neglectful parents are more likely to have a higher risk of raising an overweight child.[11] In particular, with permissive and neglectful parents, there may be an increased availability of fattening foods in the home, with less restriction on the children as to what they are allowed to eat.[12] Parents, who are strict and involved in their child’s life (authoritative parenting style) may place more restrictions on what their child eats, limiting the intake of the unhealthy foods, while increasing the availability of healthier substitutes.[12–13]

Parenting style may affect children engaging in physical activity as well. Children of authoritative parents have reported participating in more physical activities, while involving themselves in a lesser amount of sedentary behaviors.[11,14] Research suggests that the availability of family resources greatly influences the level of physical activity, as parents that are able to transport and pay for community sports organizations have children that may be more physically active.[14] This suggests that parenting style is not only linked to eating habits but also to the development of physical activity patterns in children.

Socioeconomic status. There is some evidence that if the family is considered to be in the low socioeconomic status (SES) category, which was identified by examining family income level, occupational status, and education level, there is a greater likelihood that the child’s diet will consist of foods higher in fat and the child will develop less healthy eating patterns.[15] Due to limited finances, parents may buy less healthy, cheaper foods instead of fresh fruits and vegetables, which tend to have a higher cost.[11] Therefore, foods higher in saturated fats may be found in the home environment.[11,15]

Personality. Many of the aforementioned factors may affect the rate of obesity; however, personality factors based on birth order may impact the decision to seek assistance in losing the weight. Some studies show that individuals who are the oldest in a family of three or more are described as dominant, serious, and motivated to achieve.[16–17] They may also be seen as leaders, as they tend to influence their siblings’ behavior.[10,18] Individuals who are the youngest in a family tend to be seen as carefree, persuasive, outgoing, and pampered, and the middle children are often perceived as nonconfrontational, noncompetitive, introverted, and insecure.17–19 The characteristics of the oldest and youngest child seem to be more active in nature in comparison to the middle child. These personality characteristics may influence desire to pursue surgery to manage weight.

Limitations. The results from this sample helped to show that there may be a connection between birth order and people seeking bariatric surgery, but these results are not conclusive. Various limitations surfaced during this study. First, participants who had step- or half-siblings or were adopted were not included in the study. Second, within our sample of participants, the weight status of the middle children in their family was not asked. Lastly, the literature on this subject is limited. Not only is there limited research regarding this topic, but the studies that have been published have variable results. With the publication of this study, hopefully awareness will increase and will create a desire to duplicate these results through a larger, controlled trial in order to provide more research on the topic.

In summary, this study helps to expand the research concerning those that seek bariatric surgery for help managing their weight. Genetic and environmental characteristics are risk factors for obesity, but parental and sibling factors may also influence the prevalence of obesity and the choice to choose bariatric surgery to manage weight. The results from this study indicate that there may be a connection between birth order and individuals seeking bariatric surgery. The connection leads us to believe that the parenting style and parental resources may have an effect on establishing food preferences and availability of the food with children in the home. The different parenting styles may encourage or discourage a child from eating healthy versus nonhealthy foods and their engagement in physical activity. Additionally, personality factors based on one’s birth order may affect the desire to proactively ask for help with managing obesity by seeking surgery. With further inquiry into this topic, and identifying potential risk factors, it may be possible to design interventions to decrease the prevalence of obesity.

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