3 forming a mathematical complement. sine and cosine are complementary functions. 4 (Maths, logic) (of a pair of sets, functions, etc.) mutually exclusive and exhaustive, each being the complement of the other. 5 (of genes) producing an effect in association with other genes. 6 involving or using the treatments and techniques of complementary medicine.
We know that fertility does decline. We know that after the age of 30, there is a drop in testosterone of 1 percent a year. Testosterone is the energy, the hormone that you need to make good-quality sperm.
How lower testosterone levels affect men as they age. The effects of gradually lowering testosterone levels as men grow older have received increasing attention in recent years, leading to a term known as late-onset hypogonadism.