Catalyzes the formation of aromatic C18 estrogens from C19 androgens. 3 O2 + 3 reduced [NADPH--hemoprotein reductase] + testosterone = 17beta-estradiol + formate + 4 H(+) + 4 H2O + 3 oxidized [NADPH--hemoprotein reductase] androst-4-ene-3,17-dione + 3 O2 + 3 reduced [NADPH--hemoprotein reductase] = estrone + formate + 4 H(+) + 4 H2O + 3 oxidized [NADPH--hemoprotein reductase] Belongs to the cytochrome P450 family. It is uncertain whether Met-1, Met-8 or Met-23 is the initiator.