THE ASSOCIATION BETWEEN MILK CONSUMPTION DURING CHILDHOOD AND PRECOCIOUS MENARCHE
Menarche, the last stage of the normal pubertal development in girls, is one of the most significant events in a woman’s life as it signifies that a girl is capable of becoming pregnant from then on. Furthermore, menarche also means that a girl has already faced various physiological and emotional changes that are attributable to secondary sex characteristics. In this regard, the timing of menarche is considered a factor that affects a woman’s health in her later life. Specifically, precocious menarche is known to be associated with various adverse health outcomes in adulthood such as obesity, breast and endometrial cancers, type 2 diabetes, and cardiovascular disease (CVD). Furthermore, with the decrease in the average age of menarche in girls residing in the United States, it is even more imperative to identify risk factors of precocious menarche. Although many studies have identified various factors that promote early onset of menarche, some factors still remain unclear. One such factor is milk consumption during childhood. Few studies have examined the association between milk intake during childhood and precocious menarche, and the results of studies that have examined this potential relationship have been inconsistent. Accordingly, the primary purpose of this study was to determine whether more frequent milk intake between ages 5 and 12 was associated with increased odds of precocious menarche. Self-reported data collected from 4,740 females ages 20 to 49 who participated in the 2005-2014 National Health and Nutrition Examination Survey (NHANES) were used. Weighted multivariate logistic regression was used to compute odds ratios (ORs) and 95% confidence intervals (CIs). In the unadjusted model, women who consumed milk daily and sometimes/varied between the ages of 5 and 12 had decreased odds of precocious menarche as compared to those who never/rarely consumed milk during the same period (daily: OR=0.83, 95% CI: 0.55-1.25 and sometimes/varied: OR=0.81, 95% CI: 0.45-1.47); however, this result was not statistically significant. The result remained relatively unchanged and not statistically significant after adjustment for race/ethnicity, birth cohort, country of birth, and adult body mass index (BMI) (daily: OR=0.82, 95% CI: 0.53-1.27 and sometimes/varied: OR=0.77, 95% CI: 0.42-1.43). Further studies on this topic are needed given that findings have been inconsistent. Specifically, studies with improved measurement of milk consumption by type of milk, i.e., fat level, organic/non-organic product, hormone-treated/non-hormone-treated product, and cow milk/non-cow milk, are desired to better examine the association between milk and precocious menarche.