What is an optimal number of children?
Researchers have looked at whether the more children a mother has, the better she does with both them and themselves in terms of stress. But there are large uncertainties about how many children a woman should have in relation to her own reproductive health.
Also, mothers in extremely high-risk groups may have reason to avoid trying for more children if trying would risk harming them.
A 1998 study in the UK found that the reproductive fertility of women who were effectively hypertensive were so significantly reduced that they were unlikely to conceive. If some women are so genetically predisposed that they might never conceive, then this hypothesis appears to apply.
It is thought that other groups have lower levels of metabolic variability. Therefore they might be more likely to also suffer undiagnosed illness and disability in later life.
Predicting likely success is hard, but reducing maternal risk is important if you want to boost offspring performance in educational achievement, creativity, social interaction and other abilities.