Since, therefore, openly departing from the uninterrupted Christian tradition some recently have judged it possible solemnly to declare another doctrine regarding this question, the Catholic Church, ... in order that she may preserve the chastity of the nuptial union from being defiled by this foul stain, ... proclaims anew: any use whatsoever of matrimony exercised in such a way that the act is deliberately frustrated in its natural power to generate life is an offence against the law of God and of nature, and those who indulge in such are branded with the guilt of a grave sin. - Pope Pius XI, Casti conubii
Re: the comment of Pope Pius XI, it sounds to me as if he is condemning NFP, Maeve.