First of all Tim, what a blessing that you have received the gift of seven children and have been faithfully practicing NFP for so long. As your question indicates, you and your wife both appear to approach the gift of fertility with much faith and trust in God and deep prayer.
My suggestions to your question are the following. Keep praying! Prayer is always essential in any discernment process. Continue to discuss this issue between yourselves in a spirit of trust and openness. Thanks be to God, your wife is in good health. I would encourage your wife to see her doctor to see if there are any real health concerns of which she should be aware. (If the doctor even hints at birth control or sterilization as possible remedies, kindly smile, thank him or her, and run out of there as fast as you can and find a new doctor who shares your Gospel values.) Also, although you have practiced NFP for many years, some formal training, especially in the moral and spiritual aspects of NFP, could be very helpful. I recommend finding a certified NFP trainer that is particularly knowledgeable about the health risks for women in their mid-forties. I am sure that CANFP can help you locate someone in your area.
Since your wife has been “wondering out loud” that perhaps you should try to have another baby, you should both take that into consideration in your prayer and discernment. Are you wondering the same thing? Your natural (physical and spiritual) yearnings, part of the gift of how God has created you male and female, will also help guide you in this process. However, our physical and spiritual desires must always be guided by reason and enlightened by grace. And God will always have a say in this anyway. Perhaps your desire to have another child is not His will; perhaps it is. So even if you optimize your chances to conceive, there are no guarantees. The one thing that NFP ensures, practiced of course according to God’s design and according to the mind of the Church, is that the married couple does nothing to intentionally thwart God’s will.
As regards your question about practicing continence during fertile periods, Humanae Vitae states in paragraph 16, “If, then, there are serious motives to space out births, which derive from the physical or psychological conditions of husband and wife, or from external conditions, the Church teaches that it is then licit to take into account the natural rhythms immanent in the generative functions, for the use of marriage in infecund periods only, and in this way to regulate births without offending the moral principles which have been recalled earlier”[in this Encyclical].
In your specific situation, if there were to emerge definite health risks for your wife, you would be morally justified in have recourse only to infertile periods. Also, depending on the ages and needs of your seven children, the energy level and health of your wife, and your duties (vocation) in home schooling, you may discern that you have legitimate serious motives and that conceiving another child may not be desirous at this time. These factors can and may fluctuate, causing you to revise your previous decisions. Remember, the Church calls parents to responsible parenthood, which both implies all aspects of fertility and being able to provide for the moral and physical wellbeing of themselves and of their current children. A helpful guiding principle to ensure that your recourse to infertile periods does not arise from any selfish motives at all, it would be advisable (and spiritually enriching) to practice periodic abstinence during both fertile and infertile periods.
Father Samuel W. Ward
Pastor
St. Raymond’s
Downey, California