Here is the Collect for the Mass for this day’s feast, the Immaculate Conception, in the 2002MR.
Deus, qui per immaculatam Virginis Conceptionem
dignum Filio tuo habitaculum praeparasti,
quaesumus, ut, qui ex morte eiusdem Filii tui praevisa,
eam ab omni labe praeservasti,
nos quoque mundos, eius intercessione,
ad te pervenire concedas.
Per eundem Christum Dominum nostrum. Amen.
The corrected version of the Roman Missal prepared in 2008:
O God, who by the Immaculate Conception of the Blessed Virgin
prepared a worthy dwelling for your Son,
grant, we pray,
that, as you preserved her from every stain
by virtue of the Death of your Son, which you foresaw,
so, through her intercession,
we, too, may be cleansed and admitted to your presence.
Here is the…
you prepared the Virgin Mary
to be the worthy mother of your Son.
You let her share beforehand
in the salvation Christ would bring by his death,
and kept her sinless from the first moment of her conception.
Help us by her prayers
to live in your presence without sin.