She was apparently the first: <a href="http:&#x2F;&#x2F;www.workingmother.com&#x2F;most-powerful-moms&#x2F;marissa-mayer-becomes-first-pregnant-ceo-fortune-500-company" rel="nofollow">http:&#x2F;&#x2F;www.workingmother.com&#x2F;most-powerful-moms&#x2F;marissa-maye...</a>