The Apostolic Constitutions (4th century) instruct that children are to receive communion after the various orders of clergy and consecrated laity and before the general congregation.
The reason given for the non-necessity of infant communion was articulated by the Council of Trent: The same holy council teaches that little children who have not attained the use of reason are not by any necessity bound to the sacramental communion of the Eucharist; for having been regenerated by the laver of baptism and thereby incorporated with Christ, they cannot at that age lose the grace of the sons of God already acquired.
In the Orthodox practice, the consecrated bread and wine are placed together in the chalice, and the priest administers communion with a small spoon.
There is no theological (or epistemological) reason for withholding the bread from infants; it is merely the practical concern of not giving solid food to those not ready for it.
[4] Martin Luther's Table Talk recorded his thoughts on the subject: It was asked, did the Hussites well in administering the sacrament to young children, on the allegation that the graces of God apply equally to all human creatures?
Dr. Luther replied: they were undoubtedly wrong, since young children need not the communion for their salvation; but still the innovation could not be regarded as a sin of the Hussites, since St Cyprian, long ago, set them the example.
Many Mainline Protestants practice open communion, in which the bread and wine/juice is offered to the people without discrimination of age or denominational status.
In recent years, the Eastern practice of paedocommunion has gained considerable attention in the West, including among some conservative Protestants.
Notable conservative Protestants in favor of the practice are Peter Leithart, Robert S. Rayburn, R. C. Sproul, Jr., Douglas Wilson, Rousas John Rushdoony, James B. Jordan, Gary North, and Steve Wilkins.