Spay / Neuter your pets.

You can purchase low cost spay/neuter certificates that can used at participating Birmingham Area vets through these resources.
Make sure to contact your vet to confirm they accept the certificates and if any extra costs are associated with fixing your pet. 

Alabama Animal Adoption Society
http://www.animaladoption.org/services/certificates.cfm

There is also a low cost spay/neuter clinic in Birmingham. 
http://www.alabamaspayneuterclinic.com/

Friends of Cats and Dogs Foundation
http://fcdf.org/content/spay-neuter-program