Shannon,
Washington law requires that your employer hold your job and provide certain benefits. The Washington Human Rights Commission issued regulations, which state:
(4) Leave policies.

(a) An employer shall provide a woman a leave of absence for the period of time that she is sick or temporarily disabled because of pregnancy or childbirth. Employers must treat a woman on pregnancy related leave the same as other employees on leave for sickness or other temporary disabilities. For example:

(i) If an employer provides paid leave for sickness, or other temporary disabilities, the employer should provide paid leave for pregnancy related sickness or disabilities; ...

(iv) If the employer permits extensions of leave time (e.g., use of vacation or leave without pay) for sickness or other temporary disabilities, the employer should permit such extensions for pregnancy related sickness or disabilities.

(b) There may be circumstances when the application of the employer's general leave policy to pregnancy or childbirth will not afford equal opportunity for women and men. One circumstance would be where the employer allows no leave for any sickness or other disability by any employee, or so little leave time that a pregnant woman must terminate employment. Because such a leave policy has a disparate impact on women, it is an unfair practice, unless the policy is justified by business necessity.

(c) An employer shall allow a woman to return to the same job, or a similar job of at least the same pay, if she has taken a leave of absence only for the actual period of disability relating to pregnancy or childbirth. Refusal to do so must be justified by adequate facts concerning business necessity.