income growth. statistics new zealand reported that the nation's fertility rate in 2017 was 1.81, the lowest on record. although the total number of births went up, the birth rate went down because of country's larger population thanks to high levels of immigration. new zealand's fertility rate remained more or less stable between the late 1970s and the late 2010s. younger women were driving the birth rate down, with those between the ages of 15 and 29 having the lowest birth rates on record. in 2017, new zealand teenagers had one half the number of babies of 2008, and under a quarter of 1972. meanwhile, women above the age of 30 were having more children. between the late 2000s and late 2010s, an average of 60,308 babies were born in new zealand. south america brazil's fertility rate has fallen from 6.3 in 1960 to 1.7 in 2020. for this reason, the nation's population is projected to decline by the end of the twenty-first century. according to a 2012 study, soap operas featuring small families have contributed to the growing acceptance of having just a few children in a predominantly catholic country. however, brazil continues to have relatively high rates of adolescent pregnancies, and the government is working to address this problem. notes also see how income affects human mating. more broadly, contemporary human females are evolving to reach menarche earlier and menopause later compared to their ancestral counterparts. see human evolution from the early modern period to present.