Sorry, but I don't see how this is relevant to what the other person said. Important or not, if you're too tired for sex then wtf are you going to do with an infant?
To add, often it’s these parents (potential grandparents to be) who pressure their children to have children to continue the line. It goes beyond what people are used to in the US, ie “when are you guys gonna have kids?” No, it’s more, “hey, hurry up, you owe me grandkids now, that’s why I helped you with mortgage, now get to work and deliver!”
One Chinese I talked to said there are two reasons that can play into this pressure. First reason is that the grandparents probably had the same situation themselves, they were raised by their grandparents, so now they have a urge to take the parent role themselves since they never were that close when their own children grew up. Second is the age aspect, they want to do this before they get to old and tired.
In India, a husband and wife both earning tech salary will get a full time maid for a while who may cost Rs15000 of a Rs60000 combined income, rent another 15000. Woman will spend maternity leave at her parents home, 4 paid, 2 unpaid. Either set of parents will take long vacations, even from India to US, to raise infant or toddler grandchildren, especially if they are retired.
There are cultures which shudder at couples who have to take care of an infant alone or elderly parents who live without their chidlren.