探讨孕妇孕前体重指数(body mass index，BMI)和孕期体重增长与新生儿体重的关系。

2006年7月1日至2007年6月30日，2734例于四川大学华西第二医院住院分娩且病历资料完整孕妇，按孕前体重指数分组。体重指数<16.75 kg/m²，纳入低BMI组(n＝51)，体重指数为(16.75～23.71)kg/m²纳入正常BMI组(n＝2 330)，体重指数>23.71 kg/m²，纳入高BMI组(n＝353)。根据四川大学华西第二医院推荐的孕期适宜体重增长模式，将孕期体重增长分为三类：体重增长<13.13 kg，体重增长为(13.13～20.25)kg和体重增长≥20.25 kg。将正常BMI组与高BMI组孕妇分别按体重增长进一步分为三个亚组，分析孕妇孕前体重指数和孕期体重增长与新生儿体重的关系。

低BMI组、正常BMI组和高BMI组孕妇孕前体重指数与新生儿体重的相关系数(r)分别为0.128(P>0.05)，0.138(P<0.01)和0.126(P<0.05)。低BMI组、正常BMI组和高BMI组孕妇孕期体重增加与新生儿体重的相关系数分别为0.629(P<0.001)，0.236(P<0.001)和0.195(P<0.001)。正常BMI组孕妇孕期体重增加<13.13 kg亚组1与正常BMI组体重增加为(13.13～20.25)kg亚组1比较，巨大儿发生的OR＝0.617，95%CI：0.424～0.864(P<0.01)。正常BMI组孕妇孕期体重增加>20.25 kg亚组1与体重增加为(13.13～20.25)kg亚组1比较，巨大儿发生的OR＝1.622，95%CI：1.116～2.356(P<0.01)。正常BMI组中，各体重增长亚组比较，低体重儿发生率差异无显著意义(P>0.05)。高BMI组中，各体重增长亚组比较，低体重儿、巨大儿发生率差异无显著意义(P>0.05)。

孕妇孕前体重指数及孕期体重增加与新生儿出生体重呈正相关。为降低巨大儿发生率，正常体重指数组孕期体重增加不宜超过20.25 kg。

To analyze the relationship among pre-pregnancy body mass index(BMI), gestational weight gain and birth weight.

From July 2006 to June 2007, 2734 pregnant women who delivered in the department of Obstetrics and Gynecology, West China Second Hospital of Sichuan University were enrolled in this study. They were divided into low BMI group(BMI<16.75 kg/m^2, n=51), normal BMI group(BMI: (16.75~23.71) kg/m^2, n=2330) and high BMI group(BMI>23.71 kg/m^2, n=353) based on the pre-pregnancy body mass index. In normal BMI group, patients were further divided into 3 subgroups according to the gestational weight gain, <13.13 kg group, (13.13~20.25) kg group and >20.25 kg group. The relationship among pre-pregnancy body mass index, gestational weight gain and birth weight in each group were analyzed.

The correlation coefficient(r) of body mass index to birth weight in low BMI group, normal BMI group and high BMI group was 0.128(P>0.05), 0.138(P<0.01) and 0.126(P<0.05), respectively. And the correlation coefficient of gestational weight gain in each group to birth weight were 0.629(P<0.001), 0.236(P<0.001) and 0.195(P<0.001), respectively. In normal BMI group, the incidence of macrosomia in women with gestational weight gain<13.13 kg was lower than that of women with gestational weight gain between 13.13 kg and 20.25 kg(OR=0.617, 95%CI: 0.424~0.864, P<0.05). Compared with women with gestational weight gain between 13.13 kg and 20.25 kg, the incidence of macrosomia of women with gestational weight gain more than 20.25 kg was much higher(OR=1.622, 95%CI: 1.116~2.356; P<0.05). The association between the incidence of low birth weight and gestational weight gain in normal BMI group and high BMI group had no significance (P>0.05), so did the association between the incidence of muaorosomia and gestational weight gain in high BMI group (P>0.05).

Pre-pregnancy body mass index and gestational weight gain had a positive correlation to birth weight. In order to decrease the incidence of macrosomia, gestational weight gain should be limited below 20.25 kg.