You can take 12 weeks off for the birth of a child.The employeeif protected by FMLA, is entitled to have their benefits maintained during the leave. In addition, the employer can ask for the employee to provide a fitness-for-duty certification prior to returning to work. An employee will not be able to demonstrate discriminatory animus if the employer has a legitimate non-FMLA reason for terminating the employee.
Sounds like your employer is walking a fine line, but they are providing you a non-pretextual reason for elminating you citing it as a downturn in the economy. It does have the appearance of inappropriate actions by your employer due to the timing of the termination.
By the way, if you think this was due to sexual discrimination based on your pregnancy, I would at least recommend filing a claim with either the IDHR (Illinois Department of Human Rights) and/or the EEOC.
I believe you only have about 180 days from the day of the alleged discrimination to file a claim. That would at keep your options open on your next steps while the IDHE or EEOC investigate your claim.
So I would recommend that you file that ASAP if you think this was due to sexual discrimination based on your pregnancy,
Best of Luck.