Preplanned Studies: Unhealthy Eating Behaviors During Pregnancy and Gestational Weight Gain — Huai’an City, Jiangsu Province, China, 2020–2021

Both excessive and inadequate gestational weight gain (GWG) are related to adverse maternal and neonatal health outcomes. Recent studies indicate an escalating trend in the prevalence of excessive GWG in China. One such study, using data from the China Nutrition and Health Surveys, reported that 57% of women had excessive GWG, and 13.7% of women had inadequate GWG (1). Currently, there appears to be a rise in unhealthy eating behaviors (UEBs) among the Chinese youth population such as skipping breakfast, eating fast, or frequently eating away from home. Multiple dietary guidelines globally have emphasized the critical role of avoiding UEBs to optimize GWG (2). However, very few studies have explored the relationship between these UEBs and GWG, particularly in relation to Chinese women and the newly released GWG guidelines from the Chinese Nutrition Society (CNS). The present study utilized data from 8,218 pregnant women in Huai’an City, Jiangsu Province collected between 2020–2021 to estimate the association between UEBs and GWG. The results indicated that 51.7% of women reported one or more UEBs and in addition, 55.8% of women experienced excessive GWG. Both single and multiple UEBs were found to be associated with excessive GWG. These findings underscore the public health necessity and clinical relevance of considering UEBs in the management and intervention of gestational weight, as well as in health education as part of preconception care.

The study sample comprised 27,923 pregnant women who gave birth between July 1, 2020, and June 30, 2021, in Huai’an, Jiangsu Province. The population distribution was approximately equal in terms of rural and urban residents and economic statuses. The per capita gross domestic product in Huai’an paralleled the national average. These individuals’ profiles were logged in the Maternity Information System (MIS), which includes data on basic maternal characteristics, maternal disease history, pregnancy outcomes, and basic neonatal and anthropomorphic characteristics. Of these constituents, 8,218 were solicited to take part in the Grandmothers, Mothers, and Their Children’s Health (GMATCH) inquiry, and their data was incorporated in the present analysis. Comprehensive characteristics for the participating and non-participating individuals are depicted in Supplementary Table S1. This investigation received approval from the Huai’an Maternal and Child Health Care Center Ethics Committee (Approval Number: 2021060), and written informed consent was acquired from all enrollees before the study initiation.

Four eating behaviors were assessed through a self-administered questionnaire. The conditions encompassed: eating fast (less than 15 minutes), eating meals on an irregular basis, eating away from home at least once a week, and skipping breakfast at least once a week. UEBs were classified as eating fast (under 15 minutes) (3), eating three meals irregularly (2), eating away from home at least once weekly (4), and skipping breakfast at least once weekly (4). To ensure adequate sample size, the number of UEBs was categorized into three groups: 0, 1, and at least 2. Pre-pregnancy body mass index (BMI) was computed using self-reported height and weight data prior to pregnancy. BMI ranges were subdivided into underweight (below 18.5 kg/m²), normal weight (between 18.5 and 23.9 kg/m²), overweight (between 24.0 and 27.9 kg/m²), and obese (28 kg/m² or greater) (5). GWG was calculated as the differential between pre-pregnancy weight, as self-reported, and the weight measured prior to delivery. GWG was categorized into three groups — inadequate, appropriate, and excessive — in accordance with CNS guidelines (5).

The relationships between individual and multiple UEBs and GWG were analyzed using logistic regression, presenting odds ratios (ORs) along with a 95% confidence interval (CI). For our reference group, we considered adequate GWG. Factors including maternal age, pre-pregnancy BMI, educational attainment, employment status, family income, geographical residence, physical activity level, parity, eating fast, eating three meals irregularly, eating away from home, and skipping breakfast were accounted for when adjusting the regression models. To test for a linear trend, we modeled UEB categories as a continuous variable. Stratified analyses were undertaken to assess if pre-pregnancy BMI altered the associations between multiple UEBs and GWG. Given the high prevalence of excessive GWG, using logistic regression could potentially lead to overestimated associations, hence suggesting the use of modified Poisson regression as an alternate solution. We implemented a modified Poisson regression to ascertain the relative risk association by categorizing the inadequate and adequate into a non-excessive group, measured against the excessive group. Our computations were performed using SAS (version 9.1, SAS Institute, Cary, NC), and we deemed P-values less than 0.05 to be statistically significant.

Among 8,218 pregnant participants, 55.8%, 38.2%, and 6.0% experienced excessive GWG, adequate GWG, and inadequate GWG, respectively. Out of these, 4,245 women (51.7%) reported one or more UEBs. Within this subgroup, 40.9% reported eating away from home at least one time per week. Among the women with one or more UEBs, 2,466 (58.1%) and 256 (6.0%) demonstrated excessive and inadequate GWG respectively. Women who experienced excessive GWG tended to have an elevated pre-pregnancy weight, increased weight gain during pregnancy, higher total GWG, and were typically normal weight or overweight prior to pregnancy. These women were also likely to exhibit higher education levels, elevated income, rural residency, and frequently engage in UEBs such as eating fast, eating away from home at least one time per week, and skipping breakfast at least one time per week (Table 1).

Compared to women reporting zero UEBs, those with one and two or more UEBs demonstrated an increased likelihood of excessive GWG by 18% (OR=1.18, 95% CI: 1.07–1.30) and 35% (OR=1.35, 95% CI: 1.14–1.59) respectively (P_trend<0.001) (Table 2). Each individual UEB was linked with increased odds of excessive GWG. Notably, eating fast (OR=1.15, 95% CI: 1.00–1.32) and eating away from home (OR=1.13, 95% CI: 1.03–1.25) were associated with excessive GWG even in fully adjusted models.

In the analysis stratified by pre-pregnancy BMI, among women with a normal pre-pregnancy BMI, those reporting ≥2 UEBs showed a significantly larger propensity for excessive GWG (OR=1.53, 95% CI: 1.24–1.90) in the fully adjusted model. Furthermore, overweight women reporting one UEB manifested larger odds of excessive GWG (OR=1.32, 95% CI: 1.06–1.66) (Table 3). The results of the modified Poisson regression were congruous with those of the odds ratio from the logistic regression. Detailed outcomes are presented in the Supplementary Tables S2–S3.