Chelsea is 35 years old; which is, I believe, used to be the threshold age of pregnancy for Downs’ syndrome births.
http://www.medhelp.org/search?query=down%27s+syndrome+pregnancy+at+35+risks
Yes, 35 was the measure, yet I’ve met younger and older mothers of down syndrome children. I know a family whose first child had downs and the younger 4 didn’t. So while it seems age plays a factor, it certainly isn’t the only factor.
The fact that she is an inbred hillbilly might matter.