When Mercury, the planet of communication and intellect goes retrograde, it appears to move in reverse in the sky. This creates a shift in energies that can affect our ability to receive and convey information effectively. When retrograde Mercury is in the 1st house in Sagittarius sign, it indicates that you have a strong desire to explore new ideas and gain knowledge, but the communication may be hindered during this time. 

Some possible effects of retrograde Mercury in 1st house in Sagittarius sign are:

1. Difficulty in expressing yourself clearly: You may find it challenging to articulate your thoughts and ideas, which can cause frustration and misunderstandings.

2. Delays and miscommunications: You may experience delays in receiving information, and miscommunications can lead to confusion and mistakes.

3. Revisiting old ideas: Mercury retrograde can be a time to revisit old plans and ideas and refine them with a new perspective.

4. Slowing down: Retrograde Mercury in 1st house can cause you to slow down and take extra time to think before acting, allowing you to make more informed decisions.

Overall, retrograde Mercury in the 1st house in Sagittarius sign can be a time of introspection and reflection. It's important to be patient and take time to communicate clearly and effectively during this period.

retrograde Mercury rules 7th and 10th house is in 1st house in Sagittarius