Having a large family could increase a woman's risk of having Alzheimer's by 70 percent.

New research has shown that women who give birth more than five times may be 70 percent more likely to develop Alzheimer's disease in later life. The study of more than 3,500 women in South Korea and Greece showed that pregnancy with childbirth might be associated with the condition. CNN reports that the study considered the health conditions of women over the age of 60 with the average participant age being 71. The women without Alzheimer's who had given birth five or more times also scored lower on the cognitive test than those who had given birth to fewer children. Study author Dr. Ki Woong Kim said that incomplete pregnancy was also associated with a lower risk of the disease developing. They said:

"Based on previous research, we expected that pregnancy with childbirth may be associated with the risk of Alzheimer's disease. "However we were quite surprised that incomplete pregnancy was associated with the lower risk of Alzheimer's, which we did not expect at the beginning of our research."

Women over the age of 60 are twice as likely to develop Alzheimer's over breast cancer. And while the reason why giving birth appears to increase this risk even further is yet to be confirmed, Kim thinks he has an ides why it happens. He said" "Because most incomplete pregnancies occur in the first trimester of pregnancy, it is possible that the modestly raised levels of estrogen in the first trimester of pregnancy are within the optimal range for reducing the risk of Alzheimer's disease." Many other things can also change during pregnancy, such as diet, level of exercise, and mental health. Differences in culture could also be a factor.