Kaihau Te Rangikakapi Maikara Aporo was born, according to family information, in 1863, probably in the lower Wairarapa Valley. She was the eldest child of Maikara Paranihia and her husband, Hohepa Aporo, who was the younger brother of Piripi Te Maari-o-te-rangi. Through her father she was affiliated to many of the Ngati Kahungunu hapu resident in south Wairarapa, including Ngati Hinewaka, Ngai Tukoko and Rakaiwhakairi. Through her mother, Kaihau was affiliated to Ngati Maniapoto, South Island Ngai Tahu, and Ngati Kauhi hapu of Ngati Kahungunu, resident at Papawai. Later in life Kaihau was to be strongly identified with Ngati Hinewaka hapu of Ngati Kahungunu.
During her youth Kaihau probably lived at Kohunui, near Pirinoa, with her parents and her younger siblings Te Rauhina, Hinetauira, Te Iwingaro, Hohepa and Teoti. She must have received traditional training from older relatives in genealogy and Maori custom, as she was later to be regarded as an expert in these fields. This knowledge became evident when from 1883 Kaihau represented herself and her siblings in the Native Land Court. They owned extensive land holdings at Mangamaunu, north of Kaikoura, and at Pirinoa, Papawai and around the south Wairarapa coast. She was strong-minded, even as a young woman, and appears to have once opposed her father in court concerning land at Papawai.
On 1 November 1881, according to a family Bible, Kaihau married Iraia Te Ama-o-te-rangi Te Whaiti, to whom she was distantly related. Over the next 20 years the couple were to have 13 children, although only three were to have issue: Henare (Harry), Hohaia (Joe) and Te Hioirangi (George). Iraia Te Whaiti became a successful and wealthy farmer. As a result, Kaihau was able to indulge herself and her family with very expensive furniture, clothing and other luxury items. Eventually the family relocated to Te Karearea, a large house in Greytown, where because of their wealth and generosity, Kaihau and Iraia became popular.
During the First World War Kaihau became heavily involved in the patriotic movement in Greytown, and gave a large amount of money to the cause. After Iraia died in the influenza epidemic of 1918, Kaihau assumed a matriarchal role in her family. She continued to live at Te Karearea, and maintained a close interest in the business activities of her three sons, who had inherited Iraia's estate of £36,000. She frequently looked over the accounts of the estates administered by her sons, and had a keen business sense.
In 1923 Kaihau arranged for the erection of a large marble monument to her husband at Ranana, the family cemetery. The monument outlined a number of significant historical events, together with the relevant genealogies, and is evidence of Kaihau's extensive knowledge of south Wairarapa Maori history. On another occasion a number of their genealogical records were lost; Kaihau and her son George subsequently spent much time reconstructing the records for the benefit of future generations.
Kaihau had probably been raised an Anglican, the dominant faith among Wairarapa Maori. In later years, however, she converted to the Ratana faith and in the late 1920s and 1930s regularly hosted large church gatherings at Te Karearea. She took some of her grandchildren to see T. W. Ratana at Papawai when the prophet visited in 1928. At this time Kaihau was a close friend of Niniwa-i-te-rangi, the noted Wairarapa Maori leader who had married Kaihau's brother Teoti Aporo (also known as Tamaihotua Aporo).
Kaihau lived out her life at Te Karearea, fostering her grandchildren and other juvenile relatives. She kept a strict rein on them, even to the extent of arranging their marriages. At the same time, she maintained a keen interest in her various land holdings. Known to local Europeans as 'Mrs Eli', which was taken from the English version of her husband's first name, she was also referred to as Maikara Iraia and Maikara Te Ama. Her descendants knew her as 'Granny Kaihau'. Kaihau was a short, solidly built woman with strong features and a distinctive moko. She had an excellent dress sense, and always maintained an extensive wardrobe.
Kaihau continued to exert a strong influence over her immediate and extended family until her death at Greytown on 19 January 1937. Her son George survived her. She was recognised in her obituary as a 'great chieftainess' and was buried at Ranana, next to her husband, Iraia. Eventually, the descendants of Kaihau, Hinetauira and Teoti gifted land for the Okoura Maori Reserve, which formed the basis of the Kohunui marae.