How do ‘Birth Days ’ give opportunities for resistance?

Birth Days are solely attended by women – the Wives, Aunts and the Handmaids, except for the doctors and Angel escorts. They are the perfect opportunity for the women to congregate without suspicion and discuss the things they'd not be able to talk about under any other circumstance.

Example: Offred is surrounded by the handmaids and wives; she begins to think about her experiences in the red center and how she was able to watch an "unwomen documentary." This documentary showed the antifeminist movement and her mother as part of it. The handmaids are brainwashed by the aunts in a most biased way; they only show them or read to them what they want. Many of the movies watched in Gilead are pornographic and abusive videos of women being hurt or cut into pieces.......... these are then contrasted with the feminist movement to change the way the handmaids think.