And multiple pregnancies may add to that effect, Segal says.

多胎妊娠的影响则更明显，西格尔说道。

Other risk factors include multiparity or multiple pregnancies and a maternal age over 35 years old.

其它危险因素包括多胎妊娠或者孕妇年龄大于35岁。

However, most clinics seek to minimize the chances of multiple pregnancies, as they are riskier for mothers and babies.

然而， 大多数诊所都试图将多胎妊娠的可能性降到最低，因为多胎妊娠对母亲和婴儿来说风险更大。

In fact, endometrial damage from things like a previous cesarean section, an abortion (which could be induced or spontaneous), uterine surgery, and multiparity or multiple pregnancies can all decrease vascularization and increase the risk of placenta previa.

事实上，类似先前有剖腹产、人工流产、子宫手术或者多胎多次怀孕史等均可造成子宫内膜损伤都有可能影响子宫内膜血管的生成，增加前置胎盘的风险。