these data demonstrate a ) placental aromatase activity does not appear to increase as pregnancy progresses towards parturition , b ) the bovine placenta is able to convert c21 steroids to oestrogens , and c ) induction of enzymes for converting pregnenolone or related substrates to oestrogens may be involved in the pre-partum rise in oestrogen levels .
C0032961
pregnancy
C0014939
oestrogen