In the Victorian era, fertility rates increased in every decade until 1901, when the rates started evening out. There were several reasons for this. One is biological: with improving living standards, a higher proportion of women were biologically able to have children. Another possible explanation is social. In the 19th century, the marriage rate increased, and people were getting married at a very young age until the end of the century, when the average age of marriage started to increase again slowly. The reasons why people got married younger and more frequently are uncertain. One theory is that greater prosperity allowed people to finance marriage and new households earlier than previously possible. With more births within marriage, it seems inevitable that marriage rates and birth rates would rise together.