Abstract A80: Parity and obesity in Mexican and Mexican-American women: Findings from the Ella Binational Breast Cancer Study
Authors: Pond Erika , Thompson Patricia , Martínez María E. , Wertheim Betsy C. , Cruz Giovanna , Navarro Adrian D. , Komenaka Ian , Meza Mercedes , Gutiérrez Luis Enrique , Bondy Melissa , Jacobs Elizabeth B. 
Published: June 2012

Background: Obesity rates are increasing rapidly around the globe. Obesity is associated with negative health consequences including increased risk of all-cause mortality and increased breast cancer morbidity. In the U.S., some of the highest rates of obesity are found among Hispanic women. Additionally, factors associated with low socioeconomic status have also been shown to be positively associated with obesity in the U.S., independent of race or ethnicity; higher parity (i.e., three or more full-term births) has also been implicated as a contributing factor. The aim of this study was to evaluate the independent contribution of parity on obesity in a highly parous population of Mexican and Mexican-American women diagnosed with breast cancer.

Methods: Participants are from the Ella Binational Breast Cancer Study, a study of women of Mexican descent who were 18 years of age and older at time of enrollment and who were diagnosed with invasive breast cancer within 24 months of recruitment. Each participant completed an interviewer-administered risk factor questionnaire, provided a blood or saliva sample, and consented to provide tumor tissue and access to medical record data. Obesity was defined as having a body mass index (BMI) ≥30 kg/m2, which was calculated from self-reported height and weight. Parity was defined as the number of full-term live births. Age at interview, age at first full-term pregnancy, level of education, employment, smoking status, menopausal status, age at menarche, and breastfeeding were assessed as potential confounding factors. Among U.S. participants, level of acculturation, interview language and nativity were also evaluated as confounders. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using multinomial logistic regression.

Results: Mean age was higher for U.S. compared to Mexican participants (54.4 ± 12.6 vs. 50.1 ± 12.0). Approximately 51% (n=608) of participants resided in Mexico and 49% (n=579) in the U.S. Among U.S. participants, 54% were born in Mexico and of these, 42% have lived in the U.S. &lt; 10 years. A higher proportion of the U.S. than Mexican women were classified as obese (40.8% vs. 34.5%). Parity was slightly higher among Mexican compared to U.S. women (3.9 ± 2.4 vs. 3.1 ± 1.7 births). We observed a positive association between parity and obesity. In the age-adjusted model, using women with 1–2 live births as the referent group, the OR (95% CI) for women with three full-term births was 1.49 (95% CI, 1.09–2.06). For women with four or more births, the OR (95% CI) was 1.40 (1.02–1.91); Ptrend=0.04. The association was attenuated with the inclusion of education in the model (Ptrend=0.15). When stratified by country of residence at the time of interview, the positive association persisted.

Conclusions: Our results show a significant, positive association between parity and obesity that was not independent of education. Results of our work suggest that both pre and postnatal periods are important adult life periods for health care providers to implement obesity prevention strategies and interventions.

Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):A80.