[Association and interaction of pre-pregnant body mass index and gestational weight gain of women on neonatal birthweight].

Objective: To investigate the association between maternal pre-pregnant body mass index and gestational weight gain, as well as their interaction on neonatal birthweight. Methods: We built a cohort in Anqing Municipal Hospital from January 2014 to March 2015, enrolling pregnant women who decided to give birth in this hospital. All women were asked to fill a questionnaire for basic information collection. Medical information of both pregnant women and their newborns were obtained through electronic medical record. Chi-square analysis, multinomial logistic regression, multiplicative and additive interaction methods were used to analyze the association between pre-pregnant body mass index and gestational weight gain as well as their interactions on birth weight of the neonates. Results: A total of 2 881 pregnant women were included in this study. Of the 2 881 newborns, 359 (12.46%) were small for gestational age (SGA) and 273 (9.48%) were large for gestational age (LGA). After adjusting the possible confounding factors, results from the multinomial logistic regression showed that pre-pregnancy underweight women were more possible to deliver SGA (aRR=1.33, 95%CI: 1.02-1.73). If the gestational weight gain was below the recommended criteria, the risk of SGA (aRR=1.64, 95%CI: 1.23-2.19) might increase. Pre-pregnancy overweight/obese could increase the risk of being LGA (aRR=1.86, 95%CI: 1.33-2.60). Maternal gestational weight gain above the recommendation level was associated with higher rates of LGA (aRR=2.03, 95%CI: 1.49-2.78). Results from the interaction analysis showed that there appeared no significant interaction between pre-pregnancy BMI and gestational weight on birthweight. Conclusion: Pre-pregnancy body mass index and gestational weight gain were independently associated with neonatal birthweight while pre-pregnancy BMI and gestational weight gain did not present interaction on birthweight.目的： 研究孕妇孕前BMI和孕期增重对新生儿出生体重的影响及其交互作用。 方法： 应用队列研究方法，选取2014年1月至2015年3月在安徽省安庆市立医院住院分娩的孕妇进行问卷调查，收集孕妇基本情况，并通过医院电子病历信息系统获取孕妇及新生儿信息。采用χ(2)检验、多分类logistic回归、相乘模型和相加模型分析孕妇孕前BMI、孕期增重及其交互作用与新生儿出生体重的关系。 结果： 共纳入单胎活产孕妇2 881例，其中小于胎龄儿359例（12.46%），大于胎龄儿273例（9.48%）。多分类logistic回归分析显示，控制可能的混杂因素后，孕前体重过低（aRR=1.33，95%CI：1.02~1.73）与孕期增重不足（aRR=1.64，95%CI：1.23~2.19）可增加小于胎龄儿发生风险，孕前超重/肥胖（aRR=1.86，95%CI：1.33~2.60）与孕期增重过多（aRR=2.03，95%CI：1.49~2.78）可增加大于胎龄儿发生风险；交互作用分析显示，未发现二者对新生儿出生体重存在交互作用。 结论： 母亲孕前体重和孕期增重与新生儿出生体重相关，但未发现二者之间的交互作用。.