The Cathechism states this in regards to fornification:
“
2353 Fornication is carnal union between an unmarried man and an unmarried woman. It is gravely contrary to the dignity of persons and of human sexuality which is naturally ordered to the good of spouses and the generation and education of children. Moreover, it is a grave scandal when there is corruption of the young.”
And about the gift of life it states this:
"
2378 A child is not something
owed to one, but is a
gift . The “supreme gift of marriage” is a human person. A child may not be considered a piece of property, an idea to which an alleged “right to a child” would lead. In this area, only the child possesses genuine rights: the right “to be the fruit of the specific act of the conjugal love of his parents,” and “the right to be respected as a person from the moment of his conception.”
Concerning contraception it states this:
"
2370 Periodic continence, that is, the methods of birth regulation based on self-observation and the use of infertile periods, is in conformity with the objective criteria of morality. These methods respect the bodies of the spouses, encourage tenderness between them, and favor the education of an authentic freedom. In contrast, “every action which, whether in anticipation of the conjugal act, or in its accomplishment, or in the development of its natural consequences, proposes, whether as an end or as a means, to render procreation impossible” is intrinsically evil:
Thus the innate language that expresses the total reciprocal self-giving of husband and wife is overlaid, through contraception, by an objectively contradictory language, namely, that of not giving oneself totally to the other. This leads not only to a positive refusal to be open to life but also to a falsification of the inner truth of conjugal love, which is called upon to give itself in personal totality…. The difference, both anthropological and moral, between contraception and recourse to the rhythm of the cycle… involves in the final analysis two irreconcilable concepts of the human person and of human sexuality."
“
1653 The fruitfulness of conjugal love extends to the fruits of the moral, spiritual, and supernatural life that parents hand on to their children by education. Parents are the principal and first educators of their children. In this sense the fundamental task of marriage and family is to be at the service of life.”
“
1654 Spouses to whom God has not granted children can nevertheless have a conjugal life full of meaning, in both human and Christian terms. Their marriage can radiate a fruitfulness of charity, of hospitality, and of sacrifice.”
So basically no, as a guideline it´s more or less never okay to use contraception. In very few cases there might be pastoral reasons for using contraception (non-abortive ones) but those situations and exceptions are to be made by a priest only.
If you are interested in knowing more, please take a look at Humanae Vitae by Pope Paul VI:
http://w2.vatican.va/content/paul-v...ments/hf_p-vi_enc_25071968_humanae-vitae.html