In Tale of Genji, his wife dies of an eclamsic seizure, or perhaps a pulmonary emboli, a few days post partum. The description of Aoi and her early labor suggests Preeclampsia but after childbirth she seemed weak but healthy so Genji went back to work, and then she died a sudden death.
other diaries mention childbirth:
in Sarashima diary, her sister died in childbirth.
On the moon-birth of the Rice-Sprout month my sister died after giving birth to a child. From childhood, even a stranger's death had touched my heart deeply. This time I lamented, filled with speechless pity and sorrow. While mother and the others were with the dead, I lay with the memory-awakening children one on either side of me. The moonlight found its way through the cracks of the roof [perhaps of their temporary dwelling] and illumined the face of the baby. The sight gave my heart so deep a pang that I covered its face with my sleeve, and drew the other child closer to my side, mothering the unfortunate.
and other diaries mention childbirth:
and in Murasaki's diary, there is a description of the empress having a baby.
All day long she lay ill at ease. Men cried at the top of their voices to scare away evil spirits. There assembled not only the priests who had been summoned here for these months, but also itinerant monks who were brought from every mountain and temple. Their prayers would reach to the Buddhas of the three worlds. All the soothsayers in the world were summoned. Eight million gods seemed to be listening with ears erect for their Shinto prayers. Messengers ran off to order sutra-reciting at various temples; thus the night was passed. On the east side of the screen [placed around the Queen's bed] there assembled the ladies of the Court. On the west side there were lying the Queen's substitutes possessed with [or who were enticing] the evil spirits.[17] Each was lying surrounded by a pair of folding screens. The joints of the screens were curtained and priests were appointed to cry sutras there. On the south side there sat in many rows abbots and other dignitaries of the priesthood, who prayed and swore till their voices grew hoarse, as if they were bringing down the living form of Fudo.[18] The space between the north room and the dais [on which was the Queen's bed] was very narrow, yet when I thought of it afterwards I counted more than forty persons who were standing there. They could not move at all, and grew so dizzy that they could remember nothing. The people [i.e. the ladies-in-waiting and maids-of-honour] now coming from home could not enter the main apartment at all. There was no place for their flowing robes and long sleeves. Certain older women wept secretly. Eleventh day. At dawn the north sliding doors were taken away to throw the two rooms together. The Queen was moved towards the veranda. As there was no time to hang misu, she was surrounded by kichō. The Reverend Gyocho and the other priests performed incantations. The Reverend Ingen recited the prayer written by the Lord Prime Minister on the previous day adding some grave vows of his own. His words were infinitely august and hopeful. The Prime Minister joining in the prayer, we felt more assured of a fortunate delivery. Yet there was still lingering anxiety which made us very sad, and many eyes were filled with tears. We said, "Tears are not suitable to this occasion," but we could not help crying. They said that Her Majesty suffered more because the rooms were too crowded, so the people were ordered to the south and east rooms. After this there remained in the Royal Apartment only the more important personages. The Prime Minister, Lady Sanuki, and Lady Saisho were within the [Royal] screen. The honoured priest of Ninna Temple and the court priest of Mii Temple were summoned within. The Prime Minister gave various commands, and his voice overpowered those of the priests. There were also Ladies Dainagon, Koshosho, Miya-no-Naishi, Nakatsukasa-no-Kimi, Tayu-no-Myobu, Daishikibu-no-Omoto, Tono-no-Senji—these last were venerable ladies of experience, but even they were bewildered with good reason. I am yet a novice, and I felt with all my heart that the occasion was serious. Also, in the place a little behind, outside the curtain, there were the nurses of the Princesses Naishi-no-Kami and Nakatsukasa, of the Queen's sister Shōnagon, and of her younger sister Koshikibu. These nurses forced their way into the narrow passage behind the two screens and there walked back and forth, so that none could pass that way. There were many other persons bustling about, but I could not distinguish them. The Prime Minister's son, Lieutenant-General Saisho, Major-General Masamichi of the Fourth Rank, not to speak of Lieutenant-General Tsunefusa, of the Left Bodyguard, and Miya-no-Tayu, who had not known Her Majesty familiarly, all looked over her screen for some time. They showed eyes swollen up with weeping [over her sufferings], forgetting the shame of it. On their heads rice[19] was scattered white as snow. Their rumpled clothes must have been unseemly, but we could only think of those things afterward. A part of the Queen's head was shaved.[20] I was greatly astonished and very sorry to see it, but she was delivered peacefully. The after-birth was delayed, and all priests crowded to the south balcony, under the eaves of the magnificent main building, while those on the bridge recited sutras more passionately, often kneeling.,,As the after-birth came, it was fearful to hear the jealously swearing voices of the evil spirits. Shinzo-Azari took charge of Lady Ben-no-Kurodo; Sōyo took charge of Hyoé-no-Kurodo; a priest Hojuji took charge of Ukon-no-Kurodo;[22] Chiso Azari took charge of Lady Miya-no-Naishi.,
