Preplanned Studies: Weight Status and Self-Perception of Weight Among Women of Childbearing Age — China, 2015

In the United Nations population statistics, women of childbearing age were defined as being between 15–49 years old. According to the data of the Sixth Census in 2010, the total number of women who were aged 15–49 years in China was about 380 million. Childbearing is important and it is thus important to identify factors that may influence the ability to give birth to children. Beyond age, several lifestyle-related factors, such as excess body weight, obesity, underweight, smoking, intense sporting activity, alcohol consumption, drug addiction, or abuse of other substances, have an adverse influence on female fertility (1-3). Accuracy of body weight perception is an individual’s perception of their body weight in comparison with actual body weight, and a correct self-perception of body weight status is necessary for optimal weight control. In this report, we aimed to analyze the weight status and self-perception of weight among women of childbearing age in China. The data were obtained from the China National Chronic Diseases and Nutrition Surveillance of Adults (2015). The proportion of normal weight and underweight in women of childbearing age were 54.3% and 5.7% respectively, and the incidence of normal weight and underweight was the highest in the group aged 18–24 years; the rate of overweight and obesity were 28.3% and 11.7%, respectively, and the proportion of overweight and obesity was highest in the group aged 35–49 years. Only 55.6% of women of childbearing age perceived their body weight correctly. Correct evaluation of one’s own weight is necessary for taking weight control measures for healthy weight management. Actions should be taken to improve the cognitive level of weight of women of childbearing age to guide them to correctly manage their own weight.

China National Chronic Diseases and Nutrition Surveillance of Adults was a descriptive and cross-sectional study conducted in 2015 (4). Demographic information, perception of body weight, anthropometric measures [weight, height, and body mass index (BMI)] were assessed. Trained investigators using standardized protocols measured height and weight using standardized equipment. Height was measured with a height meter (TZG type) with a minimum scale of 0.1 cm; weight was measured with an electronic scale (Tanita HD-390) with a minimum scale of 0.1 kg. A total of 43,077 women of childbearing age were included in this study, including 17,782 urban women and 25,295 rural women. Each participant was asked to rate her own body weight category as underweight, normal weight, overweight, or obese before anthropometric measurement. We calculated BMI from measured weight and height, and the women were categorized into 4 groups according to their BMI as follows (according to the Criteria of Weight for Adults of the health industry standard of China, WS/T 428–2013):

Underweight: BMI <18.5 kg/m²

Normal: 18.5≤ BMI <24.0 kg/m²

Overweight: 24≤ BMI <28.0 kg/m²

Obese: BMI ≥28.0 kg/m²

Weighted coefficients accommodated the sampling scheme for unequal probabilities of sample selection and the post-stratification weights, which harmonized the sample structure of the surveillance with that of the Sixth National Population Census in 2010 (5). Prevalence by region (urban and rural), and age were estimated. SAS software (version 9.4, SAS Institute Inc., Cary, USA) was applied for statistical analysis.

General characteristics of the sample are shown in Table 1. We investigated women of childbearing age from urban (41.3%) and rural (58.7%) areas in China and considered 3 age groups: 18–24 years (7.4%), 25–34 years (26.7%) and 35–49 years (65.9%). The mean BMI of Chinese childbearing age women was 23.6 kg/m² (23.3 kg/m² in urban areas and 23.8 kg/m² in rural areas) and increased with the age. Based on objective body weight status, 5.7% were classified as underweight, 54.3% were normal weight, 28.3% were overweight, and 11.7% were obese. The prevalence of underweight decreased with age and was 12.5% among women 18–24 years of age. The prevalence of overweight increased proportionally with increasing age as the groups aged 18–24, 25–34, and 35–49 had rates of 17.1%, 22.9%, and 36.3%, respectively. Similarly, the obese prevalence of women also increased with age, and the prevalence of obese women aged 18–24, 25–34, and 35–49 years were 7.6%, 10.2%, and 14.3%. Within each age group, women residing in rural areas were more likely to be overweight and obese than those in urban areas.

Table 2 shows the consistency of BMI and body weight perception of Chinese women at childbearing age in 2015. Among normal weight women, 28.1% underestimated or overestimated their weight, 8.6% thought they were low weight and 19.5% thought they were overweight or obese. Among underweight women, 55.7% perceived their body weight heavier than their actual body weight, in which 2.1% perceived themselves as overweight or obese. Among overweight and obese women, 42.5% perceived their body weight lighter than their actual body weight, in which 1.9% perceived themselves as underweight.

Table 3 provides the association of BMI and body weight perception. Both permutations were divided into 3 groups: consistency, underestimation, and overestimation; 55.6% women of childbearing age accurately perceived their weight status, 15.8% underestimated their weight status, and 28.6% overestimated their weight status. Women in urban areas were less likely to overestimate their weight than those in rural areas. Women aged 35–49 years were the most likely to overestimate their weight (37.2%), while young women aged 18–24 years were more likely than other ages to underestimate their weight (24.7%).