Pope St. Innocent I, in 417, Synod of Milevis : “The idea that infants can be granted the rewards of eternal life even without the grace of baptism is utterly foolish” (Denzinger 219).
Pope Innocent III,
who asserted that those dying with only original sin on their souls will suffer " "no other pain, whether from material fire or from the worm of conscience,
except the pain of being deprived forever of the vision of God” (Corp. Juris, Decret. l. III, tit. xlii, c. iii – Majores). (Denzinger 410)
John XXII, Nequaquam sine dolere, Nov 21, 1321:
“…the souls…of those who die in mortal sin, or with only original sin descend immediately into hell; however, to
be punished with different penalties and in different places.” (Denzinger 493a)
Pope Pius VI, Auctorem Fidei, Aug. 28, 1794,
“Baptism” section 3:
"The doctrine which rejects as a Pelagian fable,
that place of the lower regions (which the faithful generally designate by the name of the limbo of the children) in which the souls of those departing with the sole guilt of original sin are punished with the punishment of the condemned, exclusive of the punishment of fire, just as if, by this very fact, that these who remove the punishment of fire introduced that middle place and state free of guilt and of punishment between the kingdom of God and eternal damnation, such as that about which the Pelagians idly talk,
–[this Jansonist theory]–false rash injurious to Catholic schools." [Denzinger 1526]
Pius XII-Allocution to midwives, October 29, 1951.
“An act of love is sufficient for the adult to obtain sanctifying grace and to supply the lack of baptism;** to the still unborn or newly born this way is not open.**”
The Holy Office in 1958 (now the Congregation for the Doctrine of the Faith) provided as follows:
“The practice has arisen in some places of delaying the conferring of Baptism for so-called reasons of convenience or of a liturgical nature–**a practice favored by some opinions, lacking solid foundation, concerning the eternal salvation of infants who die without Baptism…**Therefore this Supreme Congregation, with the approval of the Holy Father, warns the faithful that infants are to be baptized as soon as possible. . . . Pastors and preachers are exhorted to urge the fulfillment of this obligation.”
The provincial Council of Cologne:
“Faith teaches us that infants, since they are **not capable of this desire, are excluded from the kingdom of heaven if they die **[unbaptized].” (Collectio Lacensis, V. 320)
PS:
The Holy Innocents were martyrs for Jesus Himself. They died in his place therefore are martyrs .
Even so Jewish boys are circumcised at 8 days and received sanctifying grace. More than likely God in his providence would have allowed no births 8 or 9 days before Herod’s slaughter.
“We must say, therefore, that grace was bestowed in circumcision”
Summa
newadvent.org/summa/4070.htm