It can be caused by various factors, including:
1. Sperm Production Issues:
Problems with sperm production are the most common cause. This includes low sperm count (oligospermia), poor sperm motility, abnormal sperm shape (morphology), or no sperm production at all (azoospermia).
2. Blockages:
Blockages in the tubes that transport sperm can prevent sperm from reaching the egg. This can be due to infections, surgeries, or congenital conditions.
3. Hormonal Imbalances:
Hormones play a critical role in sperm production. Imbalances in hormones such as testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) can impact fertility.
4. Genetic Factors:
Certain genetic conditions, like Klinefelter syndrome or Y chromosome microdeletions, can affect sperm production and function.
5. Lifestyle Factors:
Factors such as smoking, excessive alcohol consumption, drug use, obesity, and exposure to toxins can negatively affect sperm quality.
6. Medical Conditions:
Health conditions like diabetes, thyroid disease, and infections (e.g., sexually transmitted infections) can impair fertility. Varicocele, an enlargement of veins within the scrotum, is also a common cause.
7. Medications and Treatments:
Some medications, treatments for cancer (chemotherapy and radiation), and surgeries can impact sperm production and fertility.