Why isn't Rachel Weisz in the third mummy movie?

It was said by several sources, including TMZ, that Rachel Weisz passed on being in "The Mummy: Tomb of the Dragon Emperor", released August 1, 2008, to spend more time with her son Henry. He was born on May 31, 2006, so at the time it was filmed in 2007 and early 2008, he was only 1 to 2 years old. Henry's father was director Darren Aronofsky, who Weisz was in a relationship with for about 9 years and had been engaged to for 5 years. They never married, but Weisz got married to actor Daniel Craig in 2011.

Tags: rachel weiszmummytomb 
Wednesday, February 01 2012
Source: http://www.imdb.com/title/tt0859163/