As countries have developed there has been a trend towards smaller family sizes. Why does this happen?
Just to clarify, there are a few ways to subvert the one child policy in China (though I think it's less stringent these days):
1.) is if one has money to pay for an additional child or if one has a certain stature in the community which guarantees some sort of exemption
2.) is for one to give birth to subsequent children in a foreign territory
3.) is through deception (i.e. father moves with child number 1 to a certain province, and mother moves with child number 2 to a different province, pretending to be separated for a while, before reuniting again)
IELTS question, eh? Good luck ^^
Not necessarily, it honestly depends the what religion the family in particular subscribes to along with many other factors. Ever heard of Mormons and the Amish? They predominantly exist in america and tend to be 'fruitful'. Then there are countries like Japan and Sweden where women have been gaining a lot more equality and so prefer to be independent if they can. However, ummarried women over the age of 25 in Japan (and also China) are referred to pejoratively, and so I'm not surprised if the chances of them getting married exponentially decrease from that age onwards. Don't neglect the secular factor either. I believe countries where citizens are mostly secular tend to have fewer married households (i.e. cohabitation has become normal). The same goes for countries where gay marriage is officially recognised (less pressure to keep up heterosexual appearances).. aside from that, I really don't know. In the Philippines, at least amongst the socieoeconomically disadvantaged, contraception is not used very much as it's still viewed as taboo (due to the influence of Catholicism). In certain countries (usually if not exclusively developed ones) where the state provides for single mothers, abuse of the system runs rampant within the lower socioeconomic echelon. I think the whole : developed country therefore smaller family unit vs developing country therefore larger family unit is a false dichotomy. It's a misconception to view this issue in binary terms, especially when you have cases like men from developed countries fathering children during their overseas (foreign service) deployment; arabic/muslim men (not necessarily those who are based in developing countries) with multiple wives; rich east asian men/ (insert nationality of choice here) with multiple wives in different countries/cities. It's a multifaceted topic; though I agree that the traditional, preconceived notion is that of poorer families having more children for longterm economic reasons.
You putted it very straightfoward but there is truth in what you said. Modern ways of birth control allow people to decide when, if and how many children they want. Older generations didn't have that comfort?
Another reason that I think of is that old model of familly has changed (woman stays in home and take care of house and children, while man work). Nowdays girls want to be a succesful businesswomen not a home stayer. Not long ago there was a disscusion in here "Who you want to be in future~" Majority of girls answered: "Boss" none of them answered "full time mother".
Even though it is possible to be a full time mother of 5 children and be a boss at the same time it's pretty unusual.
For China, it's the result of one-child policy. Now it leads a huge problem for the whole sociaty.