The safety of any beauty procedure during pregnancy, including nano brows, largely depends on a few factors such as the type of pigments used, the cleanliness of the salon, and the individual's health and pregnancy condition.

Nano brows, or nano needling, is a semi-permanent makeup procedure that uses a nano needle to draw individual hair strokes into the skin to create natural-looking brows. The pigments used in this process are typically mineral-based, which are considered safe for most people. However, the safety of these pigments during pregnancy is not extensively studied.

One of the potential risks associated with nano brows during pregnancy is the risk of infection. This can happen if the salon does not maintain proper hygiene standards or if the skin does not heal properly post-procedure. Infections can potentially harm both the mother and the baby.

Another concern is the body's response to stress. Pregnancy alters the body's immune system and response to stress, which may affect the healing process after the procedure.

Lastly, hormonal changes during pregnancy can affect skin pigmentation, potentially altering the results of the procedure.

Given these factors, it is generally recommended to postpone any non-essential beauty procedures, including nano brows, until after pregnancy. However, if you still wish to proceed, it's crucial to discuss it with your healthcare provider and ensure the salon follows strict hygiene standards.