To make room, hormones called progesterone and relaxin signal muscles to loosen.

为了腾出空间，被称为孕酮和松弛素的激素会对肌肉发出放松的信号。

Pregnant women produce a hormone called " relaxin, " which makes the pelvis more flexible. That's good for childbirth.

怀孕的女人体内会分泌一种被称作“松弛素”的荷尔蒙，松弛素会使女性的骨盆变得更灵活。这有助于分娩。

Its job done, however, relaxin lingers in female bodies for up to a year, when softer ligaments make new mothers more prone to injury, as Jessica Ennis-Hill, an Olympic champion heptathlete, discovered in training after giving birth in 2014.

然而，正如杰西卡·恩尼斯-希尔（奥运会七项全能冠军）于2014年分娩后在训练中发现的那样，松弛素在女性体内会持续起作用长达一年之久，这时较软的韧带会使新妈妈们更容易受伤。