1. Low Sperm Count (Oligospermia): Insufficient sperm production or problems with sperm quality can reduce the chances of fertilization.

2. Poor Sperm Motility: Sperm motility refers to the ability of sperm to move effectively. Reduced motility can impair sperm's ability to reach and fertilize the egg.

3. Abnormal Sperm Morphology: Sperm with abnormal shape or structure may have difficulty penetrating the egg, leading to infertility.

4. Varicocele: A varicocele is an enlargement of the veins within the scrotum, which can affect sperm production and quality.

5. Obstructions: Blockages in the reproductive tract, such as vas deferens or ejaculatory duct obstruction, can prevent sperm from reaching the semen.

6. Hormonal Imbalances: Hormonal imbalances, including low testosterone levels or problems with the hypothalamus or pituitary gland, can affect sperm production.

7. Genetic Factors: Genetic abnormalities or conditions such as Klinefelter syndrome can impact fertility by affecting sperm production or function. Understanding the underlying causes of infertility is crucial for developing appropriate treatment plans and addressing any underlying issues that may be contributing to difficulties in conceiving.