50 years ago the average woman had five children; since then the number has halved
In the past people had many more children than today. The number fluctuated over time and there were some differences between countries, but for much of our history, the average woman had at least five children, and often more. Two centuries ago this was true for the US, the UK, Russia, India, China and many other countries for which we have data.
From 1950 onwards we have very good data from the UN Population Division. The chart here shows the average across the world: the global Total Fertility Rate. Up to 1965 the average woman in the world had more than 5 children. Since then we have seen an unprecedented change. The number has halved. Globally, the average per woman is now below 2.5 children.