英语语法分析

This is called placenta praevia.

这就是所谓的前置胎盘。

Pregnancy; Placenta praevia; Diagnosis; Treatment.

妊娠；前置胎盘；诊断；治疗。

There were not low placenta praevia in these cases.

本组病例中未遇到低置型前置胎盘。