"All the inhabitants of the palace" includes Kaṁsa. When everyone lamented, Kaṁsa joined in compassion, thinking that perhaps because of drugs or some other external means, Devakīhad undergone this abortion. The real story of what happened after Yogamāyā attracted the child of Devakī into the womb of Rohiṇī in the seventh month of Rohiṇī's pregnancy is described as follows in the Hari-vaṁśa. At midnight, while Rohiṇī was deeply sleeping, she experienced, as if in a dream, that she had undergone a miscarriage. After some time, when she awoke, she saw that this had indeed happened, and she was in great anxiety. But Yogamāyā then informed her, "O auspicious lady, your child is now being replaced. I am attracting a child from the womb of Devakī, and therefore your child will be known as Saṅkarṣaṇa."
(Srimad Bhagavatam----10:2:15----purport).

The Lord did not need to live within the womb of Devakī, for His presence within the core of her heart was sufficient to carry Him. One is here forbidden to think that Kṛṣṇa was begotten by Vasudeva within the womb of Devakī and that she carried the child within her womb.
When Vasudeva was sustaining the form of the Supreme Personality of Godhead within his heart, he appeared just like the glowing sun, whose shining rays are always unbearable and scorching to the common man. The form of the Lord situated in the pure, unalloyed heart of Vasudeva is not different from the original form of Kṛṣṇa. The appearance of the form of Kṛṣṇa anywhere, and specifically within the heart, is called dhāma. Dhāma refers not only to Kṛṣṇa's form, but to His name, His form, His quality and His paraphernalia. Everything becomes manifest simultaneously.
Thus the eternal form of the Supreme Personality of Godhead with full potencies was transferred from the mind of Vasudeva to the mind of Devakī, exactly as the setting sun's rays are transferred to the full moon rising in the east.
(Srimad Bhagavatam----10:2:18----purport).

Kṛṣṇa, the Supreme Personality of Godhead, entered the body of Devakī from the body of Vasudeva. He was beyond the conditions of the ordinary living entity. When Kṛṣṇa is there, it is to be understood that all His plenary expansions, such as Nārāyaṇa, and incarnations like Lord Nṛsiṁha and Varāha, are with Him, and they are not subject to the conditions of material existence. In this way, Devakī became the residence of the Supreme Personality of Godhead, who is one without a second and the cause of all creation. Devakī became the residence of the Absolute Truth, but because she was within the house of Kaṁsa, she looked just like a suppressed fire, or like misused education. When fire is covered by the walls of a pot or is kept in a jug, the illuminating rays of the fire cannot be very much appreciated. Similarly, misused knowledge, which does not benefit the people in general, is not very much appreciated. So Devakīwas kept within the prison walls of Kaṁsa's palace, and no one could see her transcendental beauty, which resulted from her conceiving the Supreme Personality of Godhead.
(Srimad Bhagavatam----10:2:18----purport).

According to Vedic principles, a woman, a brāhmaṇa, an old man, a child and a cow should never be killed. It appears that Kaṁsa, although a great enemy of the Supreme Personality of Godhead, was aware of the Vedic culture and conscious of the fact that the soul transmigrates from one body to another and that one suffers in the next life according to the karmas of this life. Therefore he was afraid of killing Devakī, since she was a woman, she was his sister, and she was pregnant. A kṣatriya becomes famous by performing heroic acts. But what would be heroic about killing a woman who, while confined in his custody, was under his shelter? Therefore, he did not want to act drastically by killing Devakī. Kaṁsa's enemy was within Devakī's womb, but killing an enemy in such a nescient state would not be an exhibition of prowess. According to kṣatriya rules, an enemy should be fought face to face and with proper weapons. Then if the enemy is killed, the victor becomes famous. Kaṁsa very conscientiously deliberated upon these facts and therefore refrained from killing Devakī, although he was completely confident that his enemy had already appeared within her womb.
(Srimad Bhagavatam----10:2:21----purport).

Mother Devakī, being fully transcendental, sac-cid-ānanda, does not belong to this material world. Thus the Supreme Personality of Godhead appeared with four hands, as if born from her womb. Upon seeing the Lord in that Viṣṇu form, Vasudeva was struck with wonder, and in transcendental happiness he and Devakī mentally gave ten thousand cows in charity to the brāhmaṇas. Vasudeva then offered prayers to the Lord, addressing Him as the Supreme Person, Parabrahman, the Supersoul, who is beyond duality and who is internally and externally all-pervading. The Lord, the cause of all causes, is beyond material existence, although He is the creator of this material world. When He enters this world as Paramātmā, He is all-pervading (aṇḍāntara-stha-paramāṇu-cayāntara-stham (Bs. 5.35)), yet He is transcendentally situated. For the creation, maintenance and annihilation of this material world, the Lord appears as the guṇa-avatāras-Brahmā, Viṣṇu and Maheśvara. Thus Vasudeva offered prayers full of meaning to the Supreme Personality of Godhead. Devakī followed her husband by offering prayers describing the transcendental nature of the Lord. Fearing Kaṁsa and desiring that the Lord not be understood by atheistic and materialistic nondevotees, she prayed that the Lord withdraw His transcendental four-armed form and appear like an ordinary child with two hands.
(Srimad Bhagavatam----10:3--summary).

Because Devakī was an unalloyed devotee, she could understand that the same Lord Viṣṇu had appeared as her son. Therefore, after the prayers of Vasudeva,Devakī offered her prayers. She was very frightened because of her brother's atrocities. Devakī said, "My dear Lord, Your eternal forms, like Nārāyaṇa, Lord Rāma, Śeṣa, Varāha, Nṛsiṁha, Vāmana, Baladeva, and millions of similar incarnations emanating from Viṣṇu, are described in the Vedic literature as original. You are original because all Your forms as incarnations are outside of this material creation. Your form was existing before this cosmic manifestation was created. Your forms are eternal and all-pervading. They are self-effulgent, changeless and uncontaminated by the material qualities. Such eternal forms are ever-cognizant and full of bliss; they are situated in transcendental goodness and are always engaged in different pastimes. You are not limited to a particular form only; all such transcendental, eternal forms are self-sufficient. I can understand that You are the Supreme Lord Viṣṇu."
(Srimad Bhagavatam----10:3:24----purport).

The Supreme Personality of Godhead chooses a mother and father from whom to take birth again and again. The Lord took birth originally from Sutapā and Pṛśni, then from Kaśyapa and Aditi, and again from the same father and mother, Vasudeva and Devakī. "In other appearances also," the Lord said, "I took the form of an ordinary child just to become your son so that we could reciprocate eternal love." Jīva Gosvāmī has explained this verse in his Kṛṣṇa-sandarbha, Ninety-sixth Chapter, where he notes that in text 37 the Lord says, amunā vapuṣa, meaning "by this same form." In other words, the Lord told Devakī, "This time I have appeared in My original form as Śrī Kṛṣṇa." Śrīla Jīva Gosvāmī says that the other forms were partial expansions of the Lord's original form, but because of the intense love developed by Pṛśni and Sutapā, the Lord appeared from Devakī and Vasudeva in His full opulence as Śrī Kṛṣṇa. In this verse the Lord confirms, "I am the same Supreme Personality of Godhead, but I appear in full opulence as Śrī Kṛṣṇa." This is the purport of the words tenaiva vapuṣā. When the Lord mentioned the birth of Pṛśnigarbha, He did not say tenaiva vapuṣā, but He assured Devakī that in the third birth the Supreme Personality of Godhead Kṛṣṇa had appeared, not His partial expansion.
(Srimad Bhagavatam----10:3:43----purport).

Nanda Mahārāja and Vasudeva were intimate friends, and so were their wives, Yaśodā and Devakī. Although their names were different, they were practically nondifferent personalities. The only difference is that Devakī was able to understand that the Supreme Personality of Godhead had been born to her and had now changed into Kṛṣṇa, whereas Yaśodā was not able to understand what kind of child had been born to her. Yaśodā was such an advanced devotee that she never regarded Kṛṣṇa as the Supreme Personality of Godhead, but simply loved Him as her own child. Devakī, however, knew from the very beginning that although Kṛṣṇa was her son, He was the Supreme Personality of Godhead.
(Srimad Bhagavatam----10:3:53----purport).