SB 3.3.17

uttarāyāṁ dhṛtaḥ pūror
 vaṁśaḥ sādhv-abhimanyunā
sa vai drauṇy-astra-sampluṣṭaḥ
 punar bhagavatā dhṛtaḥ
Synonyms: 
uttarāyām — unto Uttarā; dhṛtaḥ — conceived; pūroḥ — of Pūru; vaṁśaḥ — descendant; sādhu-abhimanyunā — by the hero Abhimanyu; saḥ — he; vai — certainly; drauṇi-astra — by the weapon of Drauṇi, the son of Droṇa; sampluṣṭaḥ — being burnt; punaḥ — again, for the second time; bhagavatā — by the Personality of Godhead; dhṛtaḥ — was protected.
Translation: 
The embryo of Pūru’s descendant begotten by the great hero Abhimanyu in the womb of Uttarā, his wife, was burnt by the weapon of the son of Droṇa, but later he was again protected by the Lord.
Purport: 

The embryonic body of Parīkṣit which was in formation after Uttarā’s pregnancy by Abhimanyu, the great hero, was burned by the brahmāstra of Aśvatthāmā, but a second body was given by the Lord within the womb, and thus the descendant of Pūru was saved. This incident is the direct proof that the body and the living entity, the spiritual spark, are different. When the living entity takes shelter in the womb of a woman through the injection of the semen of a man, there is an emulsification of the man’s and woman’s discharges, and thus a body is formed the size of a pea, gradually developing into a complete body. But if the developing embryo is destroyed in some way or other, the living entity has to take shelter in another body or in the womb of another woman. The particular living entity who was selected to be the descendant of Mahārāja Pūru, or the Pāṇḍavas, was not an ordinary living entity, and by the superior will of the Lord he was destined to be the successor to Mahārāja Yudhiṣṭhira. Therefore, when Aśvatthāmā destroyed the embryo of Mahārāja Parīkṣit, the Lord, by His own internal potency, entered into the womb of Uttarā by His plenary portion just to give audience to the would-be Mahārāja Parīkṣit, who was in great danger. By His appearance within the womb, the Lord encouraged the child and gave him complete protection in a new body by His omnipotency. By His power of omnipresence He was present both inside and outside of Uttarā and other members of the Pāṇḍava family.