Either of these can trigger the onset of labor and so-called true labor contractions.

它们都可以引起分娩的开始及所谓的真临产。

The first stage starts with true labor contractions and ends when the cervix is completely effaced and dilated.

第一产程从真性宫缩开始，到宫颈管完全消失，宫口完全扩张结束。

Once they start, true labor contractions progress in frequency, duration, and intensity, and they can feel like waves that build up to a peak intensity and then gradually decrease.

一旦开始，真性宫缩渐频，持续时间渐长，强度增强，而且她们可以感觉像是波积累达峰值后强度逐渐减小。