孕前BMI与妊娠期增重对大于胎龄儿发生风险的独立及联合效应

The Independent and Joint Effects of Pre-Pregnancy BMI and Gestational Weight Gain on the Risk of Large-for-Gestational-Age Infants

摘要: 目的：探讨孕前体质指数(BMI)与妊娠期增重(GWG)对大于胎龄儿(LGA)发生风险的独立影响及联合效应，为制定精准的孕前及孕期体重管理策略提供参考。方法：回顾性收集2021年~2022年在安徽医科大学第二附属医院妇产科1124例足月单胎分娩孕妇的临床资料。根据中国标准将孕前BMI分为低体重、正常体重、超重和肥胖4组，参照IOM指南将GWG分为不足、适宜和过度3组，并形成11个联合组(将低体重孕妇的“增重不足”与“增重适宜”组合并为“低体重 + 未过度增重”组)。采用Cochran-Armitage趋势性检验分析变化趋势，应用多因素Logistic回归模型校正孕妇年龄、孕周及妊娠并发症等混杂因素，分析孕前BMI、GWG单独及联合暴露与LGA风险的关联。结果：LGA总发生率为16.1% (181/1124)。趋势检验显示，LGA发生率随孕前BMI等级(Z = 5.55, P < 0.001)及GWG程度(Z = 4.86, P < 0.001)升高而显著上升。多因素分析显示，孕前肥胖(OR = 3.036, 95% CI: 1.636~5.634)和GWG过度(OR = 1.936, 95% CI: 1.335~2.807)是LGA独立危险因素。联合分析显示(以正常体重 + 增重适宜组为参照)，肥胖 + 增重过度组LGA发生风险最高(OR = 6.11, 95% CI: 2.78~13.44)，肥胖 + 增重适宜组风险亦显著升高(OR = 5.30, 95% CI: 1.40~20.03)。而两者联合的相乘交互作用分析无统计学意义(似然比χ² = 7.784, df = 6, P = 0.254)。结论：孕前肥胖和妊娠期增重过度是LGA的独立危险因素，二者联合是风险呈现显著的协同作用趋势，建议以孕前BMI为起点，实施全程化、分层化的体重管理策略。

Abstract: Objective: To investigate the independent and joint effects of pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) on the risk of large-for-gestational-age (LGA) infants, providing references for formulating precise pre-pregnancy and prenatal weight management strategies. Methods: Clinical data of 1124 women with term singleton deliveries in the Department of Obstetrics and Gynecology of the Second Affiliated Hospital of Anhui Medical University from 2021 to 2022 were retrospectively collected. Pre-pregnancy BMI was categorized into underweight, normal weight, overweight, and obesity groups according to Chinese standards. GWG was classified into inadequate, adequate, and excessive groups based on the IOM guidelines. Eleven combined groups were formed (merging “inadequate GWG” and “adequate GWG” for underweight women into an “underweight + non-excessive GWG” group). The Cochran-Armitage trend test was used to analyze trends. Multivariate logistic regression models were applied to adjust for confounding factors such as maternal age, gestational age, and pregnancy complications, analyzing the associations of pre-pregnancy BMI and GWG (both individually and in combination) with LGA risk. Results: The overall incidence of LGA was 16.1% (181/1124). Trend tests showed that the incidence of LGA increased significantly with higher pre-pregnancy BMI categories (Z = 5.55, P < 0.001) and greater GWG levels (Z = 4.86, P < 0.001). Multivariate analysis revealed that pre-pregnancy obesity (OR = 3.036, 95% CI: 1.636~5.634) and excessive GWG (OR = 1.936, 95% CI: 1.335~2.807) were independent risk factors for LGA. Joint analysis (using the normal weight + appropriate GWG group as reference) showed that the obesity + excessive GWG group had the highest risk of LGA (OR = 6.11, 95% CI: 2.78~13.44), and the obesity + appropriate GWG group also had significantly increased risk (OR = 5.30, 95% CI: 1.40~20.03). However, the multiplicative interaction analysis between the two factors showed no statistical significance (likelihood ratio χ² = 7.784, df = 6, P = 0.254). Conclusion: Pre-pregnancy obesity and excessive gestational weight gain are independent risk factors for LGA, and their combination shows a significant synergistic trend in increasing LGA risk. It is recommended to implement comprehensive, stratified weight management strategies starting from pre-pregnancy BMI assessment.