Conversation so far:
Let's start with...what does Former have to do with Serebro?
Despite original indications that Serebro was for a solo singer, it morphed into a group around the former Star Factory participant Elena Temnikova who was paired with two newcomers.
Who have been members of the group Serebro?
Serebro's members have included Marianna Kochurova, Marina Lizorkina, Elena Temnikova, Anastasia Karpova, Dasha Shashina, Polina Favorskaya , Olga Seryabkina, Katya Kischuk, Tatiana Morgunova, Irina Titova, Elizaveta Kornilova
Why did Elena leave Serebro?
On 15 May 2014 the official Serebro website reported that Elena had left the group due to ill health.
Did Polina stay with Serebro for long?
Polina Favorskaya announced she was leaving Serebro in August 2017, but continued performing with them until the end of 2017.

Question: What is Polina's birthdate?
Self-contained rewrite: What is Polina's birthdate from Serebro?