Infertility is defined as the inability of a sexually active, non-contracepting couple to achieve pregnancy within one year. When couples face difficulties conceiving despite having regular unprotected intercourse, they may be diagnosed with infertility.

Infertility can be a challenging issue for couples, both emotionally and medically. It can be due to factors related to one or both partners. 

### Causes of Infertility:

1. **Causes in Women**:
   - **Ovulatory Disorders**: Problems with ovulation are the most common cause of infertility in women. This could be due to conditions like Polycystic Ovary Syndrome (PCOS), premature ovarian failure, or functional hypothalamic amenorrhea (often related to stress, weight issues, or excessive exercise).
   - **Tubal Blockage**: Blockages or damage in the fallopian tubes can prevent sperm from meeting the egg.
   - **Endometriosis**: This condition, where tissue similar to the lining of the uterus grows outside the uterus, can affect fertility.
   - **Uterine or Cervical Abnormalities**: Abnormalities with the opening of the cervix, polyps in the uterus, or the shape of the uterus can affect fertility.
   - **Early Menopause**: Some women experience menopause before the age of 40, leading to infertility.
   - **Pelvic Inflammatory Disease**: An infection of the uterus and fallopian tubes which can cause scarring and impede fertility.
   - **Cancer and Cancer Treatments**: Certain cancers and their treatments, especially radiation and chemotherapy, can impair fertility.

2. **Causes in Men**:
   - **Sperm Disorders**: Low sperm count, poor sperm motility (movement), or abnormalities in sperm morphology (shape) can make it difficult to fertilize an egg.
   - **Erectile Dysfunction**: Difficulty with erection or ejaculation can hinder conception.
   - **Testicular Diseases**: Conditions affecting the testicles, including infections, cancer, and its treatment.
   - **Genetic Disorders**: Conditions like Klinefelter's syndrome, where a man is born with two X chromosomes and one Y chromosome, can affect fertility.
   - **Hormonal Imbalances**: Disorders of the testicles or pituitary gland can lead to hormonal imbalances affecting sperm production.

3. **Unexplained Infertility**: In some cases, despite thorough medical evaluations, the cause of infertility remains unknown.

### Diagnosis:

Both partners typically undergo medical evaluations to diagnose the cause of infertility. This may include:
- **For Women**: Pelvic exams, blood tests (to check hormone levels), ultrasounds, hysterosalpingography (to check fallopian tubes), and laparoscopy.
- **For Men**: Semen analysis, blood tests, ultrasounds, and sometimes genetic testing or biopsies.

### Treatment:

Treatments depend on the cause of infertility, its duration, the age of both partners, and personal preferences. They might include:
- **Medications**: To stimulate ovulation or increase sperm production.
- **Surgery**: To treat conditions like endometriosis, correct blockages, or other reproductive issues.
- **Assisted Reproductive Technologies (ART)**: Procedures like in vitro fertilization (IVF), where an egg is fertilized outside the body and then implanted in the woman's uterus.

### Emotional Aspects:

Infertility can be emotionally challenging for couples, often leading to feelings of inadequacy, depression, or anxiety. Seeking support, whether through counseling, support groups, or close friends and family, is essential for emotional well-being during this period.

It's important to understand that infertility is a medical condition and not a fault or failure of an individual or couple. Advances in reproductive medicine have provided numerous options and hope for many facing infertility issues.