Abiku is a Yoruba word that can be translated as "predestined to death" and refers to the spirit of a child who dies young. It is from (abi) "that which was born" and (iku) "death".
Not only is an Abiku a spirit of a child who dies young (usually considered before puberty or 12 years of age), the belief is that the spirit can return to the same mother multiple times, resulting in multiple short-lived children, or transfer to other mothers.[1] It is the belief that the spirit does not ever plan to "stay put in life" so it is "indifferent to the plight of its mother and her grief."[1][2]
When not residing in a person, the spirits are believed to live in trees, especially the iroko, baobab and silk-cotton species.[1][3] They are seen as dangerous, capable of murder, and especially likely to target children on their thirteenth birthday. They are also thought to sometimes (though rarely) eventually reach adulthood.[1]
Seen through the lens of contemporary biomedicine, the Abiku phenomenon could have been a way of understanding sickle cell carrying.[4]
"Ben Okri's novel The Famished Road is based upon an abiku. Debo Kotun's novel Abiku, a political satire of the Nigerian military oligarchy, is based upon an abiku. Gerald Brom's illustrated novel, The Plucker, depicts a child's toys fighting against an abiku," as described by Pulse. An Abiku Child's return also occurs in the writing of Slovenian Novelist Gabriela Babnik, in her novel Koža iz bombaža. We also see Wole Soyinka's poem 'Abiku' rely heavily on this occurrence. Ayọ̀bámi Adébáyọ̀'s novel Stay With Me has a couple whose children die at infancy.[5][6][7][8][9] And an abiku is the central character in Tobi Ogundiran's short story "The Many Lives of an Abiku".
A review of the oral histories around abiku note that:
"Such accounts (sometimes they are just hasty definitions) often mix facts about àbíkú with facts about ògbánje; represent àbíkú as homogeneous across time and space; fail to distinguish between popular and expert, official and heretical, indigenous and exogenous discourses of àbíkú; assume that the belief in àbíkú has a psychological rather than ontological origin; and hastily appropriate àbíkú to serve as a symbol for present-day, metropolitan concepts and concerns."[10]
10. https://www.cdc.gov/ncbddd/sicklecell/features/scd-related-death-age.html