First of all, while the Church is consistently teaching us about the damaging effects of contraception, the Church also teaches the necessity of responsible parenting and reproduction. While remaining always open to the providential gift of God, parents must carefully assess if they have the adequate capacity to welcome a new life.
The only 100% guarantee for preventing pregnancy is abstinence. While many today may consider this to be unthinkable and even inhumane, couples have to abstain regularly due to sickness, living conditions, and many other factors, sometimes for long period of time. There are many expressions of love and sex is only one of them; and in fact, being able to say no to sex may at times be the most profound expression of love when it may mean harming the other, the marriage or the family.
Other than that, there is no guarantee, besides the often irreversible methods of chemical contraception and sterilization. I call chemical contraception often irreversible because it does violence to the woman’s hormonal system and causes abortions without the user realizing. Women who use chemical contraception have altered sex drive and may end up with infertility and cancer.
Sterilization, on the other hand, definitively closes the door to life. Conditions that for the present moment prevent a couple from being ready to receive new life may pass. And this couple who may now want to receive new life can no longer do so.
Condoms also have many undesirable effects. Condoms manufacturers often claim 95% or higher effectiveness, but this is the clinical statistics. The statistics in practice is at best mid-80%, or lower for the younger age group. One of the most direct problems with condoms and other mechanical contraception methods is that they place a direct barrier between the couple. While in the very act of sexual embrace, the couple is supposed to be saying yes to unconditional union to each other, this barrier is in direct contradiction to the act, saying that I love you entirely except your fertility, or I give myself completely to you except my fertility.
Perhaps the deeper problem with contraception is that psychologically it creates room for the couple to separate sex from the practice of responsible love. When there is no possibility of having babies, couple tend not to think deeper into the persons involved, the meaning of the sexual act, and the gift of oneself to the other in the one-flesh union. The sexual embrace, which is sacred and beautiful, can easily degenerate into mere mutual gratification and abuse.
The Church, knowing the value of the sexual embrace in the life of a married couple, instead points to the natural cycle of fertility God has already given in the woman’s body. The “natural family planning” methods so called mainly consists of the Billings’ ovulation method and a similar method called Creighton Model developed at Creighton University in Omaha, Nebraska. You can obtain more technical details from woomb.org or consult your local NFP associations and practitioners.
The basic idea is from the discovery of Dr. Billings that by observing the cervical mucus, a woman can accurately predict her cycle ahead of time with a 98% accuracy. Not only that, by regularly charting her cervical mucus, a well-trained practitioner can also deduce with accuracy and precision the hormonal health of the person, and often be able to predict any significant health issue like cancer or abnormal growth in the reproductive system. Moreover, not only can NFP assist the couple in knowing when to best avoid pregnancy, more valuable, it is equally effective in helping them to achieve pregnancy.
And NFP is completely free, apart from the cost of color markers and a board to mark up the calendar.
Some may think it is Catholic contraception. Of course, it could be abused to be so. But what NFP insists is not to avoid pregnancy, since it is at best 98% accurate, always leaving room for God to act. It is rather a lifestyle training the couple to respect God’s gift of the body, and the rhythm of life He placed in the very life of the couple. At the least, it helps the husband to know his wife’s body more intimately. NFP strongly encourages that the husband should participate in some way in the charting process. And before he would come to know the complex hormonal cycles his wife needs to go through every month. This helps the couple to appreciate each other, to be more considerate, compassionate. It also trains the couple to know and be committed more transparently the reason why they need to say no to sex when they need to, and so when it is time to say yes, the embrace can be all the more truthful, passionate and complete.
Lastly, statistics has shown, while marriages across the board have a failure rate over 50%, marriages that practise NFP are five times less likely to end in divorce.