初产妇孕前体质指数及孕期体质量增加量与产程中行紧急剖宫产术风险的关系

Relationship between the risk of emergency cesarean section for nullipara with the prepregnancy body mass index or gestational weight gain

目的探讨初产妇孕前体质指数（BMI）、孕期体质量增加量与产程中行紧急剖宫产术风险的关系。方法收集2014年8月1日至2015年9月30日在首都医科大学附属北京妇产医院试产的足月、头先露、单胎初产妇6 908例，根据分娩方式分为阴道分娩组[6 416例（92.88%，6 416/6 908）]和紧急剖宫产组[产程中行紧急剖宫产术；492例（7.12%，492/6 908）]。按孕前BMI分为低体质量孕妇（BMI〈18.5 kg/m2）1 201例（17.39%，1 201/6 908）、正常体质量者（BMI为18.5~24.9 kg/m2）5 043例（73.00%，5 043/6 908）、超重及肥胖者（BMI≥25.0 kg/m2）664例（9.61%，664/6 908）；按孕期总体质量增加量，分为增加不足者[低于美国医学研究院（IOM）标准]1 155例（16.72%，1 155/6 908）、增加适宜者（符合IOM标准）2 978例（43.11%，2 978/6 908）、增加过多者（高于IOM标准）2 775例（40.17%，2 775/6 908）。应用二元logistic回归计算不同孕前BMI和不同孕期体质量增加量的孕妇产程中行紧急剖宫产术的风险。结果（1）阴道分娩组和紧急剖宫产组孕妇临床特征及妊娠结局的比较：紧急剖宫产组孕妇的年龄更大，受教育程度偏低，孕前体质量及孕前BMI更高，孕期体质量增加量更多，妊娠期高血压疾病的发生率和妊娠期糖尿病的发生率更高，分娩孕周更大、男性新生儿的比例更大、新生儿出生体质量更大、大于胎龄儿的比例更高，两组分别比较，差异均有统计学意义（P均〈0.05）。（2）不同孕前BMI孕妇产程中行紧急剖宫产术风险的比较：与孕前正常体质量孕妇比较，孕前超重及肥胖孕妇在产程中行紧急剖宫产术的风险增高（OR=1.98，95%CI为1.54~2.54；aOR=1.66，95%CI为1.27~2.16），孕前低体质量者的风险降低（OR=0.55，95%CI为0.40~0.74；aOR=0.66，95%CI为0.48~0.90）。孕期体质量增加不足和增加过多的孕妇中，与孕前正常体质量者比较，孕前超重及肥胖者产程中行紧急剖宫产术的风险升高（aOR=2.33，95%CI为1.06~5.14；aOR=1.62，95%CI为1.44~2.28），低体质量孕妇的风险均无变化（aOR=0.31，95%CI为0.07~1.32；aOR=0.66，95%CI为0.38~1.12）；孕期体质量增加适宜者中，孕前低体质量、超重及肥胖者产程中行紧急剖宫产术的风险比较，均无显著差异（aOR=0.73，95%CI为0.48~1.10；aOR=1.54，95%CI为0.94~2.54）。（3）不同孕期体质量增加孕妇产程中行紧急剖宫产术的风险比较：孕期体质量的增加量与产程中行紧急剖宫产术的风险呈正相关（aOR=1.03，95%CI为1.01~1.05）；孕期体质量增加过多者产程中行紧急剖宫产术风险，与体质量增加适宜者比较，差异有统计学意义（OR=1.30，95%CI为1.07~1.58）；校正影响因素后，差异无统计学意义（aOR=1.01，95%CI为0.82~1.24）。孕前低体质量、体质量正常、超重及肥胖孕妇中，与体质量增加适宜者比较，孕期体质量增加过多者产程中行紧急剖宫产术风险的差异均无统计学意义（aOR=1.03，95%CI为0.55~1.12；aOR=1.02，95%CI为0.80~1.30；aOR=1.03，95%CI为0.59~1.78）；孕期体质量增加不足者的风险降低（OR=0.62，95%CI为0.45~0.85；aOR=0.64，95%CI为0.46~0.88）。在孕前低体质量和超重及肥胖孕妇中，孕期体质量增加不足者与体质量增加适宜者比较，产程中行紧急剖宫产术风险差异无统计学意义（aOR=0.24，95%CI为0.06~1.01；aOR=0.90，95%CI为0.40~2.04）；在体质量正常孕妇中，与孕期体质量增加适宜者比较，孕期体质量增加不足者的风险下降（aOR=0.65，95%CI为0.45~0.95）。结论孕前超重及肥胖是初产妇产程中行紧急剖宫产术的危险因素，推荐育龄期妇女备孕时将体质量保持在正常范围内。孕期体质量增加量与产程中行紧急剖宫产术的风险相关。孕期体质量增加过多，与产程中行紧急剖宫产术的风险无明显相关性。

ObjectiveTo investigate the risk of emergency cesarean section during labor with the pre-pregnancy body mass index or gestational weight gain.MethodsA total of 6 908 healthy nullipara with singleton pregnancy and cephalic presentation who was in term labor in Beijing Obstetrics and Gynecology Hospital from August 1st, 2014 to September 30th, 2015 were recruited. They were divided into two groups, the vaginal delivery group （92.88%, 6 416/6 908） and the emergency cesarean section group （7.12%, 492/6 908）. According to WHO body mass index （BMI） classification criteria and the pre-pregnancy BMI, the 6 908 women were divided into three groups, the underweight group（BMI〈18.5 kg/m2; 17.39%, 1 201/6 908）, the normal weight group（18.5-24.9 kg/m2; 73.00%, 5 043/6 908）, the overweight and obese group （≥ 25.0 kg/m2; 9.61%, 664/6 908）. According to the guidelines of Institute of Medicine （IOM） , they were divided into three groups, the inadequate gestational weight gain （GWG） group （16.72%, 1 155/6 908）, the appropriate GWG group （43.11%, 2 978/6 908）, the excessive GWG group （40.17%, 2 775/6 908）. Unadjusted and adjusted odds ratio （OR） and confidence interval （CI） of the risk of emergency cesarean section were calculated by bivariate logistic regression.Results（1） Comparing to the vaginal delivery group, women in the emergency cesarean section group were older, with a lower education level. Their prepregnancy BMI was higer and had more gestational weight gain. They had higher morbidity of pregnancy induced hypertension and gestational diabetes mellitus. Comparing to the vaginal delivery group, the neonates in the emergency cesarean section group were elder in gestational week, with higher birth weight. More male infants and large for gestation age infants were seen in the emergency cesarean section group （all P〈0.05） . （2） Overweight and obesity were associated with the increased risk of emergency cesarean section for nullipara, with the unadjusted OR of 1.98 （95%CI： 1.54-2.54）, adjusted OR （aOR） of 1.66 （95%CI： 1.27-2.16）. In the inadequate GWG group and the excessive GWG group, overweight and obese women had increased risk of emergency cesarean section, with adjusted OR of 2.33 （95%CI： 1.06-5.14） and 1.62 （95%CI： 1.44-2.28）, respectively. In the appropriate GWG group, there was no significant difference in the risk of emergency cesarean section between the overweight and obese women and the normal weight women, with aOR of 1.54 （95%CI： 0.94-2.54）. The underweight group was associated with decreased risk of emergency cesarean section （OR=0.55, 95%CI： 0.40-0.74; aOR=0.66, 95%CI： 0.48-0.90）. While no significant difference in the risk of emergency cesarean section was found between the underweight women, the overweight and obese women, with the aOR of 0.31 （95%CI： 0.07-1.32）, 0.73 （95%CI： 0.48-1.10）, 0.66 （95%CI： 0.38-1.12）, respectively. （3） Absolute value of gestational weight gain was associated with the increased risk of emergency cesarean section, （aOR=1.03, 95%CI： 1.01-1.05）. GWG above IOM giudelines did not independently affect the risk of emergency cesarean section （OR=1.30, 95%CI： 1.07-1.58; aOR=1.01, 95%CI： 0.82-1.24）. In the underweight group, the normal weight group and the overweight or obese group, the excessive GWG women and the appropriate GWG women had no significant difference in the risk of emergency cesarean section （aOR=1.03, 95%CI： 0.55-1.12; aOR=1.02, 95%CI： 0.80-1.30; aOR=1.03, 95%CI： 0.59-1.78） , respectively. GWG below IOM giudelines was associated with decreased risk of emergency cesarean section （OR=0.62, 95%CI： 0.45-0.85; aOR=0.64, 95%CI： 0.46-0.88）. In the underweight group and the overweight or obese group, there was no significant difference in the emergency cesarean section risk between the inadequate GWG women and the appropriate GWG within women （aOR= 0.24, 95%CI： 0.06-1.01; aOR= 0.90, 95%CI： 0.40-2.04） . In the normal weight group, the inadequate GWG women had lower risk of emergency cesarean section （aOR=0.65, 95%CI： 0.45-0.95）. ConclusionsOverweight and obese women have increased risk of emergency cesarean section. The prepregnancy BMI is supposed to be an appropriate level. Absolute value of gestational weight gain is associated with increased risk of emergency cesarean section. There is no correlation between the excessive GWG and the risk of emergency cesarean section.