The answer to your question will be dependent on the size of your employer. If your employer is Kaiser, you are working for an employer that must follow the rules of the FMLA and CFRA. Under the FMLA, a father is entitled to a 12 week unpaid leave to take care of a newborn, adopted, or sick child. To qualify for this FMLA leave you need to be employed in some government agency or in a private company that has more than 50 employees, you have to have been on the job for a minimum of 12 months, as on the first day of the leave, and you must have completed 1250 work hours over the last twelve months.
However, if you and the mother of the child work in the same company, the organization has the right to limit the FMLA leave to a combined total of 12 weeks between the two employees.
Under the FMLA, you are guaranteed to get your job, or a similar job, back upon your return unless you would have lost your job anyway had you been working instead of on leave.
If your employer is not giving you your rightful leave, you should locate and consult with an experienced employment law attorney to explore your facts and determine your options. I would suggest you look either on this site in the Find a Lawyer section, or go to www.cela.org, the home page for the California Employment Lawyers Association, an organization whose members are dedicated to the representation of employees against their employers.
Good luck to you.
This answer should not be construed to create any attorney-client relationship. Such a relationship can be formed only through the mutual execution of an attorney-client agreement. The answer given is based on the extremely limited facts provided and the proper course of action might change significantly with the introduction of other facts. All who read this answer should not rely on the answer to govern their conduct. Please seek the advice of competent counsel after disclosing all facts to that attorney. This answer is intended for California residents only. The answering party is only licensed to practice in the State of California.
If your employer has at least 50 employees within a 75 mile radius from your workplace and you have worked for at least one year and have worked at least 1250 hours within that year and have not used FMLA leave, you are entitled to 12 weeks of protected leave. If your employer denies your full leave and/or refuses to reinstate you to the same or equivalent job, call an employment law attorney. That would be a violation of your rights under FMLA and the California equivalent: CFRA.