Tertullian, On the Soul 39
All that is conferred on the soul at birth the same one who envied at the beginning now also overshadows and warps, so that these gifts are neither looked to of themselves nor administered as they ought. [ALMOST NO SOUL WITHOUT A DEMON.] For to nearly no human will an evil spirit not cling, snatching souls even from the very door of birth — or invited by that whole superstition of the childbed. So all are born with idolatry as midwife, while even the wombs are still bound with bands made at the idols, and their offspring are pledged to demons.
Hence also the apostle said that the unbelieving husband is sanctified through the wife, and the unbelieving wife through the brother — otherwise your children would be unclean, but as it is they are holy — wanting the children of the faithful to be understood as marked for holiness and therefore also for salvation, that by this pledge of hope he might protect the marriages he had judged should be kept. Otherwise he remembered the Lord's definition: unless one is born of water and Spirit, he will not enter the kingdom of God — that is, he will not be holy.
Latin
[1] Quae omnia natiuitus animae conlata idem, qui in primordio inuidit, nunc quoque obumbrat atque deprauat, quominus aut ultro prospiciantur aut qua oportet administrentur. [NVLLAM FERE ANIMAM SINE DAEMONIO ESSE.] Cui enim hominum non adhaerebit spiritus nequam ab ipsa etiam ianua natiuitatis animas aucupabundus, uel qua inuitatus tota illa puerperii superstitione?
[2] Ita omnes idololatria obstetrice nascuntur, dum ipsi adhuc uteri infulis apud idola confectis redimiti genimina sua daemoniorum candidata profitentur, dum in partu Lucinae et Dianae eiulatur, dum per totam hebdomadem Iunoni mensa proponitur, dum ultima die Fata Scribunda aduocantur, dum prima etiam constitutio infantis super terram Statinae deae sacrum est. [3] Quis non exinde aut totum filii caput reatui uouet aut aliquem excipit crinem aut totum nouacula prosecat aut sacrificio obligat aut sacro obsignat, pro gentica, pro auita, pro publica aut priuata deuotione? Sic igitur et Socraten puerum adhuc spiritus daemonicus inuenit; sic et omnibus genii deputantur, quod daemonum nomen est. Adeo nulla ferme natiuitas munda est, utique ethnicorum. [4] Hinc enim et apostolus ex sanctificato alterutro sexu sanctos procreari ait, tam ex seminis praerogatiua quam ex institutionis disciplina. Ceterum, inquit, immundi nascerentur, quasi designatos tamen sanctitatis ac per hoc etiam salutis intellegi uolens fidelium filios, ut huius spei pignore matrimoniis, quae retinenda censuerat, patrocinaretur. Alioquin meminerat dominicae definitionis: nisi quis nascetur ex aqua et spiritu, non inibit in regnum dei, id est, non erit sanctus.