Reproduction

Biological reproduction is the process by which new, individual organisms are produced. Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction.

San 'Shyuum reproduction
San 'Shyuum are known to have both male and female genders, and give live birth. Their reproduction is a strictly controlled affair though, considering the extremely limited gene pool, and individuals with undesirable genomes are added to the Roll of Celibates and forbidden to produce offspring to prevent negative recessive traits from entering the San 'Shyuum gene pool. This does not prevent them from engaging in intercourse, however, and concubines are kept by high-ranking Prophets for this purpose. Illegal reproduction can result in the death of the unwanted child and sterilization of the guilty parent, even for a Hierarch.

Huragok reproduction
Huragok are the most unusual members of the Covenant, particularly in terms of reproduction. They lack genders as understood by other species - instead, two or even three Huragok work in unison to create a child, born of equal parts of the parents, sharing some memories and personality traits. While not true biological reproduction, the Huragok being artificial in origin and relying in microscopic nano-machinery to create new individuals, it still results in the creation of a new life.

Unggoy reproduction
The only known facts about Unggoy reproductive habits are that there are indeed two genders, male and female, and that they reproduce prodigiously, bearing a huge number of progeny. Exactly what means the species uses is never elaborated upon.

Yanme'e reproduction
Due to the Yanme'e insectoid bodies and use of Queens and Hives, it can be assumed that there is a dominant class within Hives. Like Ants, it may be that Yanme'e Queens produce fertile and infertile descendants. The infertile desendants would be used as Workers and Soldiers, whilst the fertile Yanme'e would be used to create more hives and keep the Yanme'e species going.

Sangheili reproduction
Sangheili are an oviparous species, laying eggs rather than giving live birth, and incubate their recently-hatched young in tank-like pods. Though nothing else is known about their direct methods of reproduction, apart from the fact that Sangheili have no external reproductive organs. This does not rule out the possibility of Sangheili possessing internal sex organs, however. This may also be an attempt to keep the game from getting "Nudity" in its ESRB rating. In the Halo Legends anime short The Duel, Han 'Chavamee, a female Sangheili, appears to have breasts similar to those of humans, possibly suggesting that they nurse their young. It is indeed possible that the organs are used in the same manner, though it should be noted that a visual similarity does not imply a functional similarity. Likewise, their inclusion may simply have been an artistic liberty, intended to allow the audience to identify with her more, rather than a canonical depiction.

Lekgolo reproduction
The sexual habits of Lekgolo, and by an extension Mgalekgolo, are not referenced in any canon material, and thus most details are based upon assumptions. Despite their being aliens, their appearance is approximately worm-like and as such it is assumed that they reproduce in the same manner as worms, asexually. It is known that each Mgalekgolo is formed from a single colony splitting in two, their dorsal spikes being the remnants of the last connections between the two parts of the colony, but this is not true reproduction in a biological sense, instead being the separation of two consciousnesses from one.

Jiralhanae reproduction
Jiralhanae have not been elaborated on in detail regarding the sexual habits of the two differing genders, and as such most assumptions made about their reproductive cycle is made through their physical appearance. Jiralhanae bear a striking resemblance to mammals which, apart from monotremes, are oviviparous, bearing live young. As such, they would likely have external reproductive organs, mate through external physical means, and give birth to live children.