Pregnancy isn’t considered a disability in the same way that cancer or MS are, but the federal government recognizes that pregnant women can be discriminated against in similar ways and has taken steps to rectify this. Under the Pregnancy Discrimination Act, pregnant women are entitled to accommodations just as disabled employees are. According to the EEOC:
If a woman is temporarily unable to perform her job due to a medical condition related to pregnancy or childbirth, the employer or other covered entity must treat her in the same way as it treats any other temporarily disabled employee. For example, the employer may have to provide light duty, alternative assignments, disability leave, or unpaid leave to pregnant employees if it does so for other temporarily disabled employees.
Employers must treat pregnancy the same way they treat all other disabilities and work with the employee to find reasonable accommodations to allow her to do her job; often they can be as simple as allowing the use of a stool while working in a position where employees are usually required to stand.
Montana does not have a separate law for pregnancy discrimination, including it under sex discrimination instead. It requires the employee be reinstated after maternity leave. According the the Department of Labor,
An employee who has signified her intent to return at the end of a reasonable leave of absence for maternity must be reinstated to her original job or to an equivalent position with equivalent pay and accumulated seniority, retirement, fringe benefits and other service credits.
In addition, Montana has a state law regarding discrimination against breastfeeding women; employers must accommodate breastfeeding and provide a place for it to occur that is not a bathroom. These accommodations make it easier for a qualified employee to continue doing her job, reducing turnover and the associated costs.