After giving birth you have iregular period but this time it is late too much for two weeks and the pregnancy test negative what could be reason be?

Possible reasons why your period is late despite a negative pregnancy test:

1. Ovulation Variation: Irregular periods are common after giving birth, and ovulation may not occur regularly for several months. This can lead to delayed periods or irregular cycles.

2. Breastfeeding: If you are breastfeeding, prolactin levels can remain high, which can suppress ovulation and delay menstruation.

3. Birth Control: If you are using birth control, such as hormonal contraceptives, they can affect your menstrual cycle and cause irregularities.

4. Stress: Physical or emotional stress can disrupt your menstrual cycle and cause delayed periods.

5. Thyroid Issues: Thyroid problems, such as hypothyroidism or hyperthyroidism, can affect your menstrual cycle.

6. PCOS: Polycystic Ovary Syndrome (PCOS) is a hormonal disorder that can lead to irregular periods, infrequent ovulation, and delayed menstruation.

7. Perimenopause: If you are approaching menopause, you may experience irregular periods and changes in your menstrual cycle.

8. Certain Medications: Some medications, such as antidepressants, antipsychotics, and chemotherapy drugs, can affect your menstrual cycle.

9. Uterine Abnormalities: In rare cases, uterine abnormalities, such as polyps or fibroids, can cause irregular bleeding or delayed periods.

It's important to consult a healthcare provider if your period is significantly delayed (more than two weeks), as some of the underlying causes may require medical evaluation or treatment.