Women who receive prenatal medical care bear healthier babies and need to spend less on medical care for their children (than do women who do bot receive.)
than 后面完整的句子是than woman bear healthier babies and need to spend less on medical care for their children who do not receive .应为划线部分和前面重复所以用do代替,比较级后面可以倒装,所以do 放在拉women前面,如果你选than who does not receive,那么than who没有先行词