The average age of mothers in the study was just over 30 years, and the average time of follow up for the children in the study was just over nine years. (sciencedaily.com)
The nursing of this many puppies at the young age of the mothers can cause life ending damage. (dogingtonpost.com)
The mean ± SD age of the mothers was 30 ± 6 years. (jamanetwork.com)