Origin of first trimester 17-hydroxyprogesterone levels as determined in pregnancies by donor oocyte fertilization

The study presented herein measured 17-hydroxyprogesterone (17-OHP) levels in women with ovarian failure who conceived by transfer of embryos which resulted from donor oocytes fertilization. A significant increase in 17-OHP during the first trimester was seen compared to baseline nonpregnant levels. The 17-OHP levels increased from a baseline average of 47.7 +/- 9.7 ng/dl to a first-trimester average of 175.8 +/- 80.6 ng/dl in the donor oocytes recipients vs. 63.0 +/- 38.0 ng/dl baseline to 295.0 +/- 83.9 ng/dl first-trimester in the control group. Initially these data may appear to contradict previous findings demonstrating a lack of 17-OHP secretion by the first-trimester placenta. However, by comparing the first-trimester progesterone (P) levels of normal pregnant women, and also measuring 17-OHP in patients with natural menopause and surgical menopause given exogenous P we concluded the following about the origin of first-trimester sera 17-OHP levels: hydroxylation of P to 17-OHP by the ovaries, some secretion by the first trimester placenta; and also increased adrenal conversion of P to 17-OHP. Contributing to the total serum 17-OHP level is the fact that there is cross-reactivity with P to 17-OHP.