Balarama

With a view to manifest Himself quickly, Lord Krishna, instructed His Yogamaya to take away and establish the seventh child at another place. If Lord Krishna had not given such an instruction to Yogamaya, then the seventh child would have taken birth in the prison only, and, Kamsa would have tried to kill this seventh child and for this purpose, when he touches this child, Kamsa would have been destroyed instantaneously. Lord Krishna thought, that if the events take place in this manner, then the Lord will not be given an opportunity to take revenge on Kamsa and this, also, will delay Lord's manifestation. Hence, He gave the order to His Yogamaya.

The entire world came to know, the result of the task undertaken by Yogamaya, on the instructions of Lord Krishna viz. the secret establishment of the foetus in mother Rohini after being lifted from mother Devaki. The entire city was kept, by Yogamaya, in such a stupor and sleep, that none knew about this secret operation. Hence, when they heard about this, the people were surprised. The people thought that mother Devaki's pregnancy was aborted. The pregnancy, at that time was about 5 to 6 months' duration, when Yogamaya had completed the task of this transfer. The people, when they came to know about the abortion, thought that this heinous act, was perpetrated by the demoniac followers of Kamsa.

— From Sri Subodhini, Verse: 10.2.5 and 10.2.16, Commentary on Çrémad-Bhägavatam (Bhägavata Puräëa) by Sri Vallabhacharya, Translated in English by Shri T. Ramanan