The large families of the past often caused the death of women, worn out by childbearing. Many women had one child while still nursing the previous one (it's a misconception that nursing prevents pregnancy). Men usually lived longer, remarried, and had more than one set of children. I've done family history studies of my ancestors and the following article rings true (and we are most definitely not Utah Mormons):

Having a large number of children is bad for parents' health--particularly that of mothers, a study suggests. US researchers looked at 21,000 couples living in Utah between 1860 and 1985, who bore a total of 174,000 children.

It was found the more children couples had, the worse their health and the more likely they were to die early.

The Proceedings of the National Academy of Science study is historical, but the experts say it helps explain both the menopause and modern family planning.

In other species, the high physical costs of bearing and raising offspring explain why having as many offspring as possible is not ideal - even though it might appear to be the most successful way of continuing the species' existence.

Research had not concluded whether or not the same was true for human reproduction....[as if a formal study were needed; ask any mother!]

They found that the couples had an average of eight children each, but family size ranged from one to 14 or more children.

The data showed that the more children a couple produced, the higher their risk of early death.

The situation was worst for women, because they were affected by the physical costs of bearing the children [not to mention at the same time raising the younger ones and doing the hard physical labor of the household and garden].

Fathers' mortality risk increased the more children they had, but never exceeded that of mothers.

The team looked at deaths after the last child was born and found mothers were also more likely than fathers to die after the last child was born.

They found 1,414 women died within a year of the last child's birth, and another 988 by the time the child was five.

In comparison, 613 men died in the first year after their last child was born, with another 1,083 dying within five years.

And the larger the family, the more likely children were to die before the age of 18, particularly if they were among the youngest.

Consider that many of these women started childbearing in their mid-teens, which meant that many of them died by their mid-30's. I saw women in India like that; by 40 they were old--wrinkled and worn out, bent and exhausted. The average life span for a woman was 45.

Menopause, unique to humans, is speculated to be the mechanism by which human women were able to stop bearing children and live long enough to raise them to adulthood and then help the next generation bear and parent the following generation.

Hooray for menopause!