目的：探讨妊娠期间正常双胎妊娠孕妇左心结构、功能及子宫动脉血流参数的变化规律。方法：选择2013年1月—2014年10月在首都医科大学附属北京妇产医院定期检查并分娩双胎妊娠孕妇，于妊娠早中期11~14周、妊娠中期21~26周及妊娠晚期28~34周行常规产前超声检查同时行成人超声心动图检查，随访后筛选入组，对正常双胎妊娠孕妇左心结构、功能及子宫动脉血流参数进行纵向研究，并与单胎孕妇进行组间比较。结果：正常双胎组50例，单胎对照组35例。①双胎组左房舒张末期内径及左室舒张、收缩末期内径随孕期增加而增加，以11~14周至21~26周间变化为著，但各孕期左心结构与单胎孕妇相比差异无统计学意义；②双胎组总血管阻力（TVR）、心输出量（CO）、心率（HR）随孕期增加而改变，以11~14周至21~26周间变化为著，E/E’随孕期增加而增高，以21~26周至28~34周间变化为著；组间比较时双胎组21~26周HR、CO及28~34周舒张压（dBP）较单胎组高；③双胎组双侧子宫动脉平均搏动指数（PI）、阻力指数（RI）、收缩期峰值流速/舒张末期流速（S/D）随孕期增加而降低，双侧子宫动脉舒张早期切迹存在率随孕期增加而降低，以11~14周至21~26周间变化为著；双胎组各孕期双侧子宫动脉平均PI、RI、S/D及11~14周舒张早期切迹存在率较单胎组低（P<0.05）。结论：①双胎妊娠孕妇左心结构内径、心输出量、心率随孕周增加而增长，总血管阻力及子宫动脉血流参数随孕周增加而减低，以早中孕期变化显著，中晚孕期左室充盈压增长迅速；②与单胎孕妇相比，双胎孕妇中孕期心率、心输出量及晚孕期舒张期血压高，各孕期子宫动脉血流参数低，早孕期舒张早期切迹存在率低。

Objective: To longitudinally investigate maternal left cardiac morphology, function and uterine artery resistances in uncomplicated twin gestations. Methods: Women with twin pregnancies, who were examined and delivered in Beijing Obstetrics and Gynecology Hospital between January 2013 to October 2014, were enrolled prospectively and underwent serial fetal ultrasound examination and maternal echocardiography at 11~14 weeks, 21~26 weeks and 28~34 weeks of gestation. Those with any complications were excluded. Left cardiac morphology, function and uterine artery resistances were assessed longitudinally and compared with those obtained at the same gestational age periods in a group of singleton gestations. Results: There were 50 normal twin pregnancies and 35 singleton pregnancies as controls. In twin pregnancies, left atrial end-diastolic dimensions, left ventricular end-diastolic and end-systolic dimensions showed significant increase throughout the pregnancy period, especially between 11~14 weeks and 21~26 weeks, but the difference was not statistically significant between twin pregnancies and control group. Total vascular resistance(TVR), cardiac output(CO) and heart rate(HR) changed throughout the pregnancy period, especially between 11~14 weeks and 21~26 weeks. E/E' increased throughout the pregnancy period and grew rapidly between 21~26 weeks and 28~34 weeks. Compared with singletons, HR and CO were significantly higher at 21~26 week and diastolic blood pressure(dBp) was significantly higher at 28~34 weeks in twins. Bilateral uterine artery mean pulse index(PI), resistance index(RI) and ratio of peak-systolic to end-diastolic blood flow velocities(S/D) decreased significantly in twins throughout the pregnancy period. The existence of early-diastolic notch decreased significantly especially between 11~14 weeks and 21~26 weeks. Bilateral uterine artery mean PI, RI and S/D at each period and the existence of early-diastolic notch at 11~14 weeks were significantly lower in twins than in singletons(P<0.05). Conclusions: In twin pregnancies, left cardiac dimensions, CO and HR showed significant increase. TVR and uterine artery resistances decreased throughout the pregnancy period, especially between the first and second trimester. Left ventricular filling pressure was growing fast between the second and third trimester.Compared with singletons, HR and CO were significantly higher at the second trimester, dBp was significantly higher at the third trimester in twins, and uterine artery resistance was lower at each time period. The existence of early-diastolic notch was lower at the first trimester.