Found in the spellings of Atkinson, Aitchison, Acheson, Aicheson, and Aitcheson, it is as a patronymic form of the medieval male given name Atkin or Adkin, itself a double diminutive of the Hebrew name 'Adam', meaning 'red earth'.
But for natural conception, age rarely keeps women from getting pregnant until they are over 40. Even in their early 40s, though, most women are still able to get pregnant, especially if they use ovulation prediction.
A woman who becomes pregnant at age 35 has a risk of 1 in 365 of having a baby with Down's Syndrome. That risk increases to 1 in 100 with a woman 40 years of age and approximately to 1 in 40 for women 45 years of age.