Fertility effect or "supporting effect?" -Quantity of children and parental health

Using the Chinese Longitudinal Healthy Longevity Survey, we try to identify the effect that quantity of children has on the health statuses of elderly parents. After dealing with a potential endogeneity problem using instrumental variable estimation, we find no significant long-arm "fertility effect," but do find a positive" supporting effect" of the quantity of children on parental health. That is, giving birth to more children has no significant effect, but the availability of additional children in old age has a beneficial effect on health during that time. Further investigation yields a more significant effect on mothers than on fathers, and a more pronounced effect on cognitive health than on physical health, as measured by occurrences of hypertension.