“A Jewish fetus is not considered viable until it graduates from medical school”

American Jewish families have valued education. Brooklyn-born comedian, actress and television host Joan Rivers (1933-2014) was quoted in a Washington (DC) Post profile on June 11, 1986:
 
“When does a Jewish fetus become a viable human being? At the end of medical or law school.”
 
It’s uncertain when Rivers first said the joke, and if she was the first to say it. The joke is a Jewish classic and is usually not credited to any author.
 
“Jewish dropout: A boy who didn’t get his Ph.D.” is a similar joke.
         
 
Wikipedia: Joan Rivers
Joan Alexandra Molinsky (June 8, 1933 – September 4, 2014), widely known as Joan Rivers, was an American comedian, actress, voice actress, writer, producer, and television host noted for her often controversial comedic persona—alternatingly self-deprecating or sharply acerbic, especially toward celebrities and politicians.
 
11 June 1986, Washington (DC) Post, “Rivers, on Her Own And Talking It Up: Irrepressible & Ever Embattled, She Forges Into the Next Chapter” by David Richards, pg. B9, col. 1:
The quips, thousands of them, run from Abortion (“When does a Jewish fetus become a viable human being? At the end of medical or law school”) ...
 
Google Books
The Jewish Riddle Collection:
A Yiddle’s Riddle
By Reb Reeven and Reeve Robert Brenner
New York, NY: Shapolsky Publishers : Distributed by the Carol Pub. Group
1991
Pg. 69:
Q. When is a Jewish fetus considered viable?
 
Google Books
God in the Wilderness:
Rediscovering the Spirituality of the Great Outdoors with the Adventure Rabbi
By Jamie S. Korngold
New York, NY: Three Leaves Press
2007
Pg. 67:
As the joke goes, “When is a Jewish fetus considered viable? When it graduates from medical school.”
 
Twitter 
Fred rosen‏
@Derfdogdreams
When does a Jewish fetus become viable?
When it finishes Medical school.
4:08 PM - 29 Mar 2010
 
Google Books
Instructions Not Included:
A Pediatrician’s Prescription for Raising the Best Kids on the Block
By Irwin H. Berkowitz
BookBaby
2014
Pg. ?:
An old, not-so-politically correct joke asks, “When does a Jewish fetus become viable?” The answer: “After it graduates medical school.”
 
Twitter
Mayor McDuck‏
@mayormcduck
It’s said that a Jewish fetus is viable once it graduates from medical school, but that lets people off the hook of completing residency.
8:31 PM - 1 Jul 2016
   
WABE 90.1 (Atlanta, GA)
Waiting Tables And Failure Led To Brad Zimmerman’s Success
By GABBIE WATTS • May 19, 2017
City Lights with Lois Reitzes
(...)
The old joke is that a Jewish fetus is not considered viable until it graduates from medical school, so Zimmerman said his choice of waiting tables was quite disappointing to his parents.