Understanding male fertility

Male fertility refers to a man's ability to cause pregnancy in a fertile female. It depends on the quantity and quality of sperm, which are produced in the testes and released during ejaculation.

1. 1

   Day 1–74: Spermatogenesis

   Immature cells in the seminiferous tubules of the testes develop into mature sperm cells over 74 days. Hormones, testosterone, FSH, and LH, regulate the whole process. Lifestyle changes made today affect the sperm produced in three months.

2. 2

   Maturation in the epididymis

   After production, sperm travel through the epididymis, a coiled tube behind each testis, where they gain the ability to swim and become capable of fertilisation. This maturation phase takes about 12 days.

3. 3

   Ejaculation: the fertilisation window

   During ejaculation, sperm mix with fluid from the seminal vesicles and prostate to form semen. A healthy ejaculate contains 16 million or more sperm per ml (WHO 2021 reference range). Only one is needed to fertilise an egg, but sperm quality across count, motility, and morphology all affect the odds.

Many factors can affect sperm quality and quantity: • Age, sperm quality gradually declines after age 40 • Lifestyle, smoking, excessive alcohol, recreational drugs, and obesity all reduce fertility • Heat exposure, tight underwear, hot baths, laptops on the lap, and prolonged sitting can raise scrotal temperature • Medical conditions, varicocele, infections, hormonal imbalances, undescended testes • Medications, some prescribed medications can affect sperm production • Stress, chronic stress can affect hormone levels and sexual function • Environmental toxins, exposure to pesticides, heavy metals, and industrial chemicals

In South Asian communities, additional factors may include higher rates of type 2 diabetes and vitamin D deficiency, both of which can affect fertility.

Most male fertility advice is written as if all men are the same, but the evidence does not support that. Research comparing men investigated for infertility has found that men of South Asian heritage can show higher sperm DNA fragmentation, damage to the genetic material inside the sperm, than White European men, a difference a standard semen analysis does not measure. South Asian men also carry a higher background rate of type 2 diabetes and insulin resistance, both of which affect sperm quality over time. None of this is a verdict, and none of it is your fault. It is a reason to test properly rather than assume, and to treat the whole metabolic picture, not just the sperm.

If you and your partner have been trying to conceive for 12 months without success (or 6 months if your partner is over 36), the male-factor workup belongs on the table at the same time as the female-side investigations, not after.