Objective
The objective of the study was to assess the infertility patient knowledge of reproductive outcomes affected by obesity.
Study Design
This was a prospective survey study of 150 female infertility patients in an academic medical center. Subjects were administered the Rapid Estimate of Adult Literacy in Medicine–Short Form and a questionnaire on the health risks of obesity, and investigators obtained height and weight measurements.
Results
Subjects’ age ranged from 21 to 45 years (mean 34.8 ± 4.94 SD) and body mass index ranged from 17.9 to 62.9 kg/m 2 (mean 26.5 ± 7.54 SD). The following percentages of women were aware that obesity increases the risk of infertility (82.7%), irregular periods (70.0%), miscarriage (60.7%), cesarean section (48.7%), breast cancer (38.7%), birth defects (29.3%), stillbirth (22.7%), and endometrial cancer (20.7%).
Conclusion
Among women with infertility, there is limited knowledge of reproductive outcomes affected by obesity. Public education is needed to increase awareness. Women undergoing fertility treatment are motivated for reproductive success and may be uniquely receptive to obesity education and weight loss intervention.
Obesity is a health issue of epidemic proportions worldwide and in the United States. The World Health Organization (WHO) defines normal weight as a body mass index (BMI) of 18.5-24.9 kg/m 2 , overweight as a BMI of 25-29.9 kg/m 2 , and obesity as a BMI of 30 kg/m 2 or greater. In 2008, it was estimated that up to 10% of all medical spending in the United States ($147 billion) was attributable to the medical burden of obesity. It is predicted that by the year 2030, there will be 65 million more obese adults in the United States and the resultant medical costs will increase by $48 billion to $66 billion per year.
For Editors’ Commentary, see Contents
Obesity is a particularly important concern in the health of women because 64.1% of women in the United States are overweight or obese. The association between increased weight and cardiometabolic disease is widely recognized, but obesity also plays a significant role in the development of reproductive disorders by increasing the risk of infertility, breast cancer, and endometrial cancer.
Obesity is also associated with a number of pregnancy complications including miscarriage, stillbirth, birth defects, and cesarean section. The effects of maternal obesity extend beyond the pregnancy because there is increasing evidence of an association between maternal obesity during pregnancy and childhood obesity in offspring. Interventions targeting maternal obesity therefore present a unique opportunity to reduce the risk of obesity and related metabolic derangements in future generations.
The population of women seeking care in an infertility clinic is of particular interest because they uniformly present for preconception medical care and are highly motivated. Furthermore, an obesity intervention would be expected to have a positive impact on the ability of these patients to achieve pregnancy and improve their obstetric outcomes. Fertility providers are becoming increasingly aware of the adverse reproductive outcomes associated with obesity and the potential for preconception intervention, resulting in debate over whether access to fertility treatments should be restricted in patients over a certain BMI. The possible societal impact of weight loss intervention prior to pregnancy in this population is significant: according to the Centers for Disease Control and Prevention, 146,244 assisted reproductive technology cycles were performed in the United States during 2009, resulting in the live birth of 60,190 infants.
Although there is abundant public information available on the effect of overweight and obesity on cardiometabolic and reproductive health, there are very few published studies that assess patient understanding and awareness of these risks, particularly as they pertain to women’s reproductive health. While several studies demonstrate the public’s limited knowledge of obesity as it pertains to cancer risk and obstetric outcomes, we found no published studies that examined the knowledge among infertility patients of the relationship between obesity and reproductive health.
The purpose of this study was to assess the knowledge of BMI and the general and reproductive health risks associated with obesity in a cohort of women seeking infertility treatment. We hypothesized that women are aware that excess body weight increases the risk for cardiometabolic diseases such as diabetes and hypertension but are less aware of the effect of excess body weight on reproductive outcomes such as infertility, miscarriage, and endometrial and breast cancer.
Materials and Methods
Subjects
A convenience sample of women seeking care in the Reproductive Endocrinology and Infertility clinic at Northwestern Memorial Hospital was recruited. Women were approached at the time of check-in and offered a card describing the study. All eligible participants were approached sequentially as they presented to the clinic over the course of 13 months, subject to investigator availability. A total of 211 women were approached for participation and 150 agreed to participate (71.1% capture rate). Participation was restricted to English-speaking, nonpregnant women between the ages of 18 and 45 years, with no additional inclusion or exclusion criteria including BMI.
Surveys
Participants completed the Rapid Estimate of Adult Literacy in Medicine–Short Form (REALM-SF), a validated 7-item word recognition test to assess patient health literacy. The REALM-SF was verbally administered to participants by a study investigator in a private setting. The highest possible REALM-SF score is 7, which is equivalent to a high school reading level and implies that a woman will likely be able to read and understand most patient education materials. A REALM-SF score of 4-6 is equivalent to a seventh- to eighth-grade reading level and implies that a woman may struggle with most patient education materials.
Subjects then completed a questionnaire on the health risks of obesity developed by the investigators based on current literature and terminology from the WHO. A hard copy of the questionnaire ( Appendix , Supplementary Figure ) was distributed directly to patients who consented to participate. Demographic factors including age, race, education level, and annual household income were collected. The questionnaire assessed 3 principal components: self-perception of height and weight; knowledge of BMI; and knowledge of the effects of obesity on general, cardiometabolic, and reproductive health outcomes.
Participants’ knowledge of the relationship between excess weight and various health outcomes was assessed by asking, “Does excess body weight (weighing more than you should) increase the risk of the conditions listed below?” Response choices included “yes,” “no,” and “not sure.” Conditions not associated with obesity, such as eczema, lactose intolerance, and tuberculosis, were added as distractors. Participants who responded “yes” (that excess weight increased the risk of the condition) were considered as having knowledge that obesity is associated with an increased risk of that condition.
Survey results were entered into a database . Data entry was confirmed by random review of 20% of the entered surveys by one of the investigators (M.E.B.).
Clinical measurements
Height was measured in inches with a scale-mounted stadiometer. Weight was measured in pounds with a balance-beam scale. Measured height and weight were converted to metric units and used to calculate participants’ BMI. The BMI of each participant was calculated from measured height and weight as well as from self-reported height and weight. Participants were categorized into BMI groups based on the WHO classifications using their measured BMI. Self-reported height, weight, and BMI were compared with measured values.
Institutional review board status
This prospective study was reviewed and approved by the Northwestern University Institutional Review Board. Written informed consent was required and obtained from all of the study participants.
Statistical analysis
A sample size of 96 surveys was calculated to be sufficient to result in survey responses having a 95% confidence interval of ± 10%. All demographic and clinical measurements are reported as mean ± SD. The χ 2 test was used to determine the interaction between the demographic variables and patients’ knowledge of the effect of obesity on specific conditions as well as the interaction between patient BMI classification and demographic variables. Pearson’s correlation was used to determine the association between the self-reported vs actual weight and height. A P < .05 was considered to be statistically significant. All statistical analyses were performed in SPSS (PASW version 18) software (SPSS Inc, Chicago. IL).
Results
Demographics
A total of 150 women (71.1% of the 211 who were initially approached) completed the study. Detailed demographic data are summarized in the Table . The study population ranged in age from 21 to 45 years (mean 34.8 ± 4.94 years), and 54.7% of study participants identified themselves as white and 26.7% as black. Most of the participants (86.6%) had at least 4 years of college education and 54% of participants reported a total annual household income of greater than $100,000. Almost all of participants (96.0%) had a REALM-SF score of 7. The BMI of study participants ranged from 17.9 to 62.9 kg/m 2 (mean 26.5 ± 7.54 kg/m 2 ). Fifty-four percent of the subjects had a normal BMI, 19.3% were overweight, and 24% were obese.
| Demographic | Value | |
|---|---|---|
| Age, y b | 21–45 | 34.8 (4.94) |
| BMI, kg/m 2 b | 17.9–62.9 | 26.5 (7.54) |
| BMI category, prevalence % | ||
| Underweight (BMI <18.5 kg/m 2 ) | 2.7 | |
| Normal range (BMI 18.5–24.9 kg/m 2 ) | 54.0 | |
| Overweight (BMI 25.0–29.9 kg/m 2 ) | 19.3 | |
| Obese class I (BMI 30.0–34.9 kg/m 2 ) | 10.7 | |
| Obese class II (BMI 35.0–39.9 kg/m 2 ) | 7.3 | |
| Obese class III (BMI >40.0 kg/m 2 ) | 6.0 | |
| Race, prevalence % | ||
| White | 54.7 | |
| Black | 26.7 | |
| Hispanic | 6.7 | |
| Asian | 8.7 | |
| Other | 3.3 | |
| Education level, prevalence % | ||
| Eighth grade or less | 0.7 | |
| High school or GED | 2.7 | |
| Some college | 10.0 | |
| 4 year college degree | 41.3 | |
| Master’s degree | 36.0 | |
| Doctoral degree | 9.3 | |
| Annual household income, prevalence % | ||
| <$10,000 | 0.0 | |
| $10,000 to <$25,000 | 3.3 | |
| $25,000 to <$50,000 | 7.3 | |
| $50,000 to <$75,000 | 20.7 | |
| $75,000 to <$100,000 | 13.3 | |
| $100,000 to <$150,000 | 19.3 | |
| >$150,000 | 34.7 | |
| REALM-SF score, prevalence % | ||
| 5 | 1.3 | |
| 6 | 2.7 | |
| 7 | 96.0 | |
a Demographic data were collected for all 150 participants. REALM-SF scores were available for 149 participants because 1 participant refused to complete the assessment;
Correlation of BMI classification with demographics
There was a statistically significant correlation between being overweight and race ( P = .031) and between being obese and race ( P = .029), with white subjects less likely to be overweight or obese. A statistically significant correlation was found between being overweight and income ( P = .003) and between being obese and income ( P < .001), with subjects who earned a total annual income of greater than $100,000 less likely to be overweight or obese. A statistically significant correlation was found between being obese and education ( P = .003), with subjects having at least 4 years of college education less likely to be obese.
BMI knowledge
When asked, “What percentage of women in the United States do you think weigh more than they should?” only 36.2% of subjects correctly identified the range of 61–80% ( Figure 1 , A). Of the 150 participants, 145 (96.7%) had heard of the term “BMI.” Of these, 42 (29%) thought they knew their own BMI, and 17 (40.4%) of these women correctly knew their own BMI within ± 1 kg/m 2 ( Figure 1 , B). Therefore, only 11.3% of all participants actually knew their own BMI. When asked “Which BMI range is considered ideal?” only 47.3% were able to identify the correct range of 18.5–24.9 kg/m 2 ( Figure 1 , C).
Validity of self-report
We asked participants to self-report their current height (in inches) and weight (in pounds), after which height and weight were measured by study personnel. There was high correlation between self-reported and actual weight (R 2 = 0.99 and P < .0001; Figure 2 , A) and height (R 2 = 0.91 and P < .0001; Figure 2 , B).
Self-perception of current weight
We asked, “When you think about your current weight, do you consider yourself underweight, normal weight, overweight, or very overweight?” Of those who were actually underweight (n = 4), 2 (50%) identified themselves as underweight and 2 (50%) as normal weight. Of those who were actually normal weight (n = 109), 69 (63.3%) identified themselves as normal weight, 2 (1.8%) as underweight, and 38 (34.8%) as overweight. Of those who were actually overweight (n = 16), 14 (87.5%) thought they were overweight and 2 (12.5%) thought they were very overweight. Of those who were actually obese (n = 20), 14 (70%) thought they were very overweight and 6 (30%) thought they were overweight.
Knowledge of the effects of obesity on general health and cardiometabolic and reproductive outcomes
Figure 3 shows the percentages of women who were aware that obesity increases the risk of the following: high blood pressure (94.7%); diabetes (93.3%); heart disease (92.7%); high cholesterol (92.0%); and arthritis (49.3%). Figure 3 also shows the percentages of women who were aware that obesity increases the risk of the following: infertility (82.7%); irregular periods (70.0%); miscarriage (60.7%); cesarean section (48.7%); breast cancer (38.7%); birth defects (29.3%); stillbirth (22.7%); and endometrial cancer (20.7%). Women incorrectly thought that obesity increases the risk of the following: early menopause (37.6%); osteoporosis (35.8%); iron deficiency anemia (19.3%); eczema (12.8%); cystic fibrosis (12.2%); lactose intolerance (10.8%); and tuberculosis (6.0%).
Correlation of demographics and BMI with knowledge of the health effects of obesity
We found a statistically significant correlation between education and knowledge of the effect of obesity on the risk of diabetes ( P = .039), hypertension ( P = .019), infertility ( P = .003), and breast cancer ( P = .017), with higher educational level associated with correct response. No statistically significant correlation was found between race or income and knowledge of the effect of obesity on any of the health outcomes.
We found no statistically significant correlation between being overweight or obese and having knowledge of any of the health outcomes (general, cardiometabolic, or reproductive) affected by obesity.
Results
Demographics
A total of 150 women (71.1% of the 211 who were initially approached) completed the study. Detailed demographic data are summarized in the Table . The study population ranged in age from 21 to 45 years (mean 34.8 ± 4.94 years), and 54.7% of study participants identified themselves as white and 26.7% as black. Most of the participants (86.6%) had at least 4 years of college education and 54% of participants reported a total annual household income of greater than $100,000. Almost all of participants (96.0%) had a REALM-SF score of 7. The BMI of study participants ranged from 17.9 to 62.9 kg/m 2 (mean 26.5 ± 7.54 kg/m 2 ). Fifty-four percent of the subjects had a normal BMI, 19.3% were overweight, and 24% were obese.
