关于more...than...用法

题目

关于more...than...用法
more...than...结构表示“比……多”时,
more后面的内容是否要和than后面的平行?
主要是麻烦看一下这句句子,结构怎么看?
According to public health officials,in 1998 Massachusetts became the first state in which more babies were born to women over the age of thirty than under it.
脑子有点混,忽然看不明白这句句子.感觉more和than后内容不平行诶～
句子感觉than后面是省略了什么,但一般不是只能省略助动词吗?

答案

这句话的意思是：
据官方显示,1998年马塞诸塞成了第一个30岁以上的产妇比30岁以下的产妇多的州.（反映马塞诸塞州高龄产妇的问题）.
其实后面有省略了,如果不省略的话应该是这样吧：
...more babies were born to women over the age of thirty than babies were born to women under the age of thirty.