Interspecies reproduction
{{aquote|All Starfleet personnel must obtain authorization from their C.O., as well as clearance from their Medical Officer, before initiating an intimate relationship with an alien species.|Ensign Harry Kim citing Starfleet protocol|2375|The Disease}}Interspecies reproduction' was the coupling of two different species for the purpose of reproduction, which would produce a hybrid offspring. 

Because of the common genetic ancestry throughout the Milky Way Galaxy, by way of the ancient humanoids, many species were able to interbreed with or without the help of genetic technology. ()

There can be unexpected consequences to interspecific relations and, as such, it was a researched topic. Ktarian Doctor Mizan was an expert in interspecies mating practices, known for his "empirical research." () Starfleet Academy had a semester on interspecies protocol, as well as Starfleet's handbook on personal relationships that was three centimeters thick. ()

One should note that there can be certain difficulties involved in reproducing between species, even humanoid, for anatomical reasons; for instance, not all species keeping their genitals in the same place (), or incompatible number of required genitals (), or the embryo not surviving to term due to genetic or physical causes, such as life-threatening birth defects or dangers to the mother during birthing which may require caesarean section or fetal transport to save one or both. Following the birth of the Ktarian / Human hybrid Naomi Wildman, The Doctor noted that "there's no sign of any interspecies abnormalities." ()

Seska believed that Cardassian / Human cross breeding was possible, as she attempted to have Chakotay's child. (She did nevertheless prove that a Cardassian / Kazon hybrid was possible.) () Gilora Rejal made the same assumption when she expressed an interest in reproducing with Miles O'Brien. ()

Q indicated that a Human / Q hybrid was possible, and also stated that  could breed with, or as, any species because of their godlike abilities. (; ) 

Benjamin Sisko briefly assumed that Ilon Tandro was the son of Curzon Dax and Enina Tandro. ()

Although they decided not to, Kes and Neelix seemed to imply it was possible for them to procreate. ()

Klingons and Trill were capable of reproducing with medical help. ()

 Appendices 
 See also 
 Interspecies Protocol

 Background information 
According to the original script of , interbreeding between Humans and the Greek god species was also possible, as Carolyn Palamas got impregnated by Apollo. However, this was cut from the actual episode, but was later used in the Star Trek: New Visions comic Of Woman Born''. 

Ronald D. Moore opined that as a changeling, Odo could not reproduce with solids. 
Sex and reproduction