Intuitively, we assume that as a person's social status increases, so too do their options for breeding, and thus we assume they are more likely to breed. This is somewhat true of men, but not so of women.
A study by Hopcroft (2015) found a negative correlation with personal income, intelligence and education (measures of social status) and the number of offspring a woman has. However, this study was conducted within contemporary U.S,(https://www.sciencedirect.com/science/article/pii/S1090513814001330), but there does seem to be a worldwide pattern. If we take countries not exactly known for having high personal income, education or women's rights, such as Niger and Somalia, we can see that their fertility rates are 7.2 and 6.3, whereas the U.S. sits at 1.8, and other 1st World Countries, such as Australia and the U.K, sit at almost identical rates.
Perhaps an explanation for this is women's hypergamy. Hypergamy is a necessary tool for women, given their role in reproduction. Moreover, men can take 30 seconds to fulfil their part in sexual reproduction, whereas a woman takes 9 months to fulfil hers. Thus, since a woman's capacity to breed is far more restricted, she needs to be choosier in her partners. So, in relation to this article, as a woman increases her social status, her potential breeding partners decreases also, because she doesn't want to trade down, given her hypergamy (that would be an evolutionary bad decision). This is not to say that women are "gold diggers" (as this stupid Wikipedia article says: https://en.wikipedia.org/wiki/Hypergamy), but rather they have been programmed, through evolution, to feel this way.
Another explanation, not one which is mutually exclusive to the above, is that women in poorer countries feel it necessary to breed more, given the likelihood of infant mortality. Again, to use data as illustration, Niger and Somalia have infant mortality rates of 48 and 80 per 1000, whereas the U.S., Australia and the U.K. all have infant mortality rates of under 10, and Australia has 3 (https://data.worldbank.org/indicator/SP.DYN.IMRT.IN?year_high_desc=false).
