请问！名词后面接过去分词的用法（非被动）

请大神们帮忙解答一下，看新闻时看到的句子，也是语法问题~

--- Women diagnosed within five years of their last childbirth were almost three times more likely to die than other similary aged breast cancer patients who had not given birth.

--- My friends hadn't known the baby existed.

方案1，非谓语动词，过去分词放名词后面是被动。

Who is the boy that is locked behind the door. 可以变成>> Who is the boy locked behind the door.

但是，能像上述这样变化的，只是在限定修饰从句中。

如果是这种用法，那么第一句原句还原成：woman that is diagnosed within five years ... 解释通顺吗？

                                   第二句还原成： the baby who is existed. 解释不通顺

方案2，非谓语动词，过去分词也可以表示“已经”这种状态。

但是，顺序应该是diagnosed woman，the existed baby。就像a retired man。

所以原句的用法到底是怎样的呢？

请求大家的帮助~！