Anecdote: my wife works for a biotech company and her firm has more way more women than men. She does statistical programming and her entire group (I think 4-6 people?) are women. Coming from more conventional engineering companies that always lean overwhelmingly male, I've found this fascinating.
I don't know if it's a feature of biotech specifically or just her company (which offers good maternity leave by the way, and the employees make use of it).