OvaScience, a Cambridge company specializing in fertility treatments, announced Wednesday that it has completed a $37 million Series B financing. The financing was led by General Catalyst. Existing investors, Bessemer Venture Partners and Longwood Fund, were joined by new investors BBT Capital Management Advisors, LLC, Cycad Group, Hunt BioVentures, and RA Capital, among others. OvaScience plans to use the proceeds from the financing to support the development and commercialization of its fertility treatment approaches based on the egg precursor cell discoveries of OvaScience cofounder Jonathan Tilly.