双胎妊娠妇女适宜孕期增重及其与妊娠结局的关系

Gestational weight gain in twin pregnancies and its association with maternal and neonatal outcomes

目的探讨双胎妊娠妇女适宜孕期增重及其与妊娠结局的关系。方法本研究为回顾性研究。研究对象为2012年1月1日至2015年6月30日在上海交通大学医学院附属国际和平妇幼保健院分娩的双胎妊娠孕妇。先选择妊娠结局良好，且无妊娠合并症或并发症的孕妇711例，计算其孕期增重，将这些孕妇的孕期增重的P25-～P75定为适宜孕期增重范围。在此基础上，选择足月双胎、无妊娠合并症的孕妇504例，分析孕期增重范围与妊娠结局的关系。采用t检验、方差分析或x2检验对数据进行统计学分析。结果（1）初步确定双胎足月妊娠孕妇（37孕周）的适宜增重范围为15．3～21．4kg。体重过低[体重指数（body mass index，BMI）〈18．5]、正常体重（≥18．5～〈25．0）和超重肥胖（≥25．0）双胎孕妇孕期增重[M（P25～P75）]分别为18．5（15．8-22．2）、18．3（15．3～21.3）和18．1（14．9～21．5）kg，3组差异无统计学意义（F=0．121，P=0．886）。（2）对504例根据前述适宜孕期增重范围分为增重过低组（低于推荐范围下限）137例，增重正常组（孕期增重在推荐范围内）238例和增重过高组（孕期增重高于推荐范围上限）129例。分析发现，随孕期增重水平增加，新生儿出生体重明显增大『分别为（2626．1±225．8）、（2680．1±237．9）和（2751．9±257．1）g，F=9．189，P〈0．011；双胎出生体重均≥2500g的孕妇所占比例略呈上升趋势，但差异无统计学意义[3组分别为51．1％（70／137）、60．5％（144／238）和64.3％（83／129），x2=5．279，P=0．071]。孕期增重过低组、正常组及过高组相比，妊娠期糖尿病的发病风险呈下降趋势f分别为31．4％（43／137）、14．7％（35／238）和9．3％（12／129），x2=25．144，P〈0．01]，而妊娠期高血压疾病（包括妊娠期高血压和子痫前期）的发病风险差异无统计学意义。504例足月双胎妊娠孕妇中，妊娠期糖尿病患者90例（17．8％），其孕前平均BMI为22．5±2．8，高于非患病孕妇的21．2±2．9（t=3．735，P〈0．01）；妊娠期高血压疾病（包括子痫前期和妊娠期高血压）患者共67例（13．3％），其孕前平均BMI为22．4±2．8，高于未患病孕妇的21．3±2．9（t=2．767，P=0．006）。结论孕前BMI对孕期增重的影响不明显。孕期增重达到或超过推荐的适宜增重范围，且在一定范围内时，能够有效提高新生儿出生体重，且未见增加妊娠期并发症（包括妊娠期糖尿病、妊娠期高血压和子痫前期）的发生风险。

Objective To investigate the optimal gestational weight gain （GWG） in twin pregnancies and to analyze the impact of GWG on pregnant outcomes. Methods A retrospective cohort study of twin pregnancies was conducted on women who gave birth in International Peace Maternity and Child Health Hospital, Shanghai Jiaotong University School of Medicine from January 1, 2012 to the June 30, 2015. An optimal range of GWG was calculated based on the amount of weight gain in 711 subjects who gave birth to normal twins and with uncomplicated pregnancy. Another 504 twin pregnant women without gestational complications were recruited for further analysis of the relationship between GWG and gestational outcomes. T-test, analysis of variance and Chi-square test were used for statistical analysis. Results （1） The optimal range of GWG for full-term twin-pregnancy was 15.3-21.4 kg. In those with low body mass index （BMI, 〈18.5）, normal BM1 （≥ 18.5-〈25.0） and overweight/obesity （≥ 25.0）, the GWG [M（P25-P75）] were 18.5 （15.8-22.2）, 18.3 （15.3 21.3） and 18.1 （14.9-21.5） kg, respectively. There was no significant difference in GWG among those groups （F=0.121, P=0.886）. （2） According to the optimal GWG mentioned above, we divided the 504 cases into three groups, including lower GWG group （less than the optimal GWG, n=137）, normal GWG group （in the GWG range, n=238） and higher GWG group （more than the optimal GWG, n=129）. The neonatal birth weights in the three groups were （2 626.1 ±225.8）, （2 680.1±237.9） and （2 751.9±257.1） g （F=9.189, P〈0.01）, respectively, indicating that neonatal birth weight was increased by increasing GWG. The proportion of both twins with birth weights of more than 2 500 g was slightly increased, but there was no significant difference among the three groups [51.1% （70/137）, 60.5% （144/238） and 64.3% （83/129）, respectively, X2=5.279, P=0.071]. The incidence of gestational diabetes mellitus （GDM） was reduced along with increased GWG [31.4% （43/137）, 14.7% （35/238） and 9.3% （12/129）, respectively, x2=25.144, P〈0.01 ], while the incidence of hypertensive disorders in pregnancy （HDP, including gestational hypertension and preeclampsia） in the three groups showed no significant difference. There were 90 cases （17.8%） of GDM in the 504 cases with a pre-pregnancy BMI of 22.5±2.8, which was higher than that of the non-GDM cases （21.2± 2.9）, （t=3.735, P〈0.01）. Among the 504 cases, there were 67 cases （13.3%） of HDP （including gestational hypertension and preeclampsia） with a pre-pregnancy BMI of 22.4± 2.8, which was higher than that of the non-HDP patients （21.3±2.9, t=2.767, P=0.006）. Conclusions The pre-pregnancy BMI has little influence on GWG in twin pregnancies. Increasing GWG to the recommended optimal range or above, and within a certain range, could promote an increase in neonatal birth weight without adding the risks of gestational complications, such as gestational diabetes mellitus, gestational hypertension and preeclampsia.