Is "Knocked Up" a Knock-Off?

Canadian author, Rebecca Eckler, is claiming one of the best romantic comedies of the summer (one movie that I have actually had a chance to see) was stolen from her book of the same name, “Knocked-up.”  It looks like she is in for an uphill battle since her main contentions are:

• the cover of her book and the cover of the screenplay are similar;
• the main character gets pregnant after celebrating; and,
• the father is a Jewish Canadian.

I guess the real question is whether this is just another a knock-off of the Da Vince Code lawsuit.