"Why not? Jesus wore imperfect clothes, imperfect sandals, ate imperfect food, and lived with imperfect people for 33 years. I think he could probably tolerate 9 months more imperfection to accomplish his goal."
Well said! He is God and came to earth to be one of us! He was tempted in all things but never sinned! He was exposed to injuries like hitting his hand accidentally with a hammer and he sneezed from dust and so forth. His mother was blessed among women not because she was sinless but because she submitted to the perfect will of God. It was a righteous decision. She knew what would be rumored about her pregnancy and still made the decision to suffer whatever happened to her because of her obedience to the will of God. She was not sinless, otherwise the Savior died for nothing because of Mary.
And the suggestion that any human being was sinless diminishes the importance of Jesus's sinlessness and the price he paid for us.