生不了孩子可以用英语表达为 "unable to have children"。
这个表达方式来源于英语中 "have children" 的常用表达方式，表示 "生育、拥有子女" 的意思。
例句：
She was unable to have children due to a medical condition. (由于一个医学状况，她生不了孩子。)
He was unable to have children because of a low sperm count. (他生不了孩子，因为精子数量低。)
They were unable to have children and decided to adopt. (他们生不了孩子，所以决定收养。)