Examining Crotch Lengths at the Trochanterion Plane by Using 3D Body Scanning To Suggest Considerations for Improving Sizing of Absorbent Underwear Panels and Pads

Abstract

Introduction: Women's underwear garments typically include a crotch panel, which is an extra layer of fabric attached inside of the garment, taking the shape of the perineal region and extending over the orifices to absorb or wick moisture away from that area (LaBat & Ryan, 2019). Therefore, this panel, or other absorbent products such as hygienic pads that are attached to this panel to take in urine leakage and vaginal or period discharge should be properly sized based on the size of the body to provide comfort to the wearer (LaBat & Ryan, 2019). Previous studies found that age, BMI, and race were important factors for developing fitted patterns at the crotch area (Song & Ashdown, 2011). In a comparative study of trouser patternmaking methods, it was found that front and back crotch lengths and crotch width should be increased with aging to provide comfort (Lim & Cassidy, 2017). The same study examined the crotch length differences between Asian and Western women and found significantly longer crotch length in the Asian cohort. Anthropometric data related to underwear sizing and fit for women is very limited, and information on optimum positioning of the crotch panel from anterior to posterior planes is not available. Due to the limited number of studies about the size of crotch length, the main purposes of the present study were to better understand (1) the sizing of women's underwear as well as commercial hygienic pads (i.e. sanitary pads and panty liners), and (2) the correlations between the length of crotch panel among women with varying age, size, BMI, hip measurements, and race.Methods: A multi-method approach was used to address the goals of this study. Upon receiving an IRB approval, a Qualtrics survey was conducted via Amazon MTurk to better understand female consumers' experiences with commercial hygienic pads. Participants self-reported their panty sizes, weight, and height, and hygienic pad sizes. To measure crotch lengths, a total of 544 3D body scans of North American women (aged 18-45) from CAESAR database were used. Trochanterion was determined as the body landmark to set a baseline when extracting the measurements. To extract data related to crotch length at the trochanterion plane, and anterior to posterior depth, profile silhouettes were captured from the CEASAR database. Adobe Illustrator was used to connect the front and back side lines. FreeCAD was used to get absolute crotch coordinates, which were used to detect and measure front, back, and total crotch's lengths in Adobe Illustrator. Seven body measurements (i.e., height, front and back curve lengths, total curve length, anterior-posterior length, max-hip girth, and depth) were compared based on participants' BMI, race, and age to analyze the correlations among the variables. Descriptive statistical analyses, regressions, ANOVA and Pearson's correlation tests at 95% confidence level were conducted in SPSS 25. Results: One hundred and seventy useable survey responses were collected from women aged 18 years and older. Most of the particip...