What are the reasons for the delay of one week without menstruation?

Patient's question:

Patient: My girlfriend
20 years old
Last month, my girlfriend also had her period delayed by a week, arriving on the 21st.
This month, on the 27th, we used a pregnancy test and it was negative.
We have been using condoms consistently this month, and each time we checked, there was no breakage.
But she still hasn’t gotten her period. Could it be due to weather changes?
She is very afraid of cold.

Doctor's answer:

Irregular menstruation has many causes, which are typically classified into two major categories in clinical practice: one is functional, such as irregular menstruation caused by endocrine dysfunction; the other is organic, such as conditions like pelvic inflammatory disease, endometritis, and endometriosis, which can also lead to irregular menstruation.
Go to the hospital for a check-up and take medication as prescribed. In your daily diet, consume more foods that boost qi and blood, or traditional Chinese medicine herbs for regulating menstruation, such as Angelica sinensis (Danggui), Astragalus membranaceus (Huangqi), and Leonurus cardiaca (Yimucao). Drink plenty of water, eat less spicy and irritating foods, pay attention to a balanced diet, and exercise more.
Wishing you good health.