Delayed luteo-placental shift of progesterone production in IVF pregnancy

Objective: To observe absolute and relative levels of progesterone, 17 alph a-hydroxyprogesterone (17-OHP) and human chorionic gonadotrophin (hCG) in i n vitro fertilization (IVF) pregnancies after withdrawal of luteal support. Method: Single blood samples were obtained from 41 pregnant women followin g IVF treatment and 43 normal pregnant women at various weeks gestation wit hin the first trimester. Progesterone, 17-OHP and hCG were measured by immu noassay. Results: Serum levels of progesterone, but not of hCG, in IVF preg nancies were significantly greater than in normal pregnancies up to 8 weeks post-conception, despite discontinuing luteal support 2 weeks after concep tion. The ratio of progesterone to 17-OHP, a predominantly ovarian product, in normal pregnancies rose between 4 and 9 weeks but did not change over t he same period in IVF pregnancies. Conclusion: The luteal contribution to m aternal serum levers of progesterone is much higher in IVF pregnancies comp ared with normal pregnancies. This is sustained throughout the first trimes ter without the need for luteal support and obscures the placental contribu tion of progesterone for much longer than in normal pregnancies. Progestero ne or hCG supplements may therefore be unnecessary in IVF pregnancy. (C) 20 00 International Federation of Gynecology and Obstetrics.