Implantation: Endometrial and placental protein markers and ovarian steroids in serum during in-vitro fertilization cycles

The objective of this study was to find the earliest time atwhich it was possible to detect clinical pregnancy in an in-vitrofertilization (IVF) treatment cycle supported with human chorionicgonadotrophin (HCG), and also retrospectively to diagnose abnormalovarian- or endometrium-related situations in failure cycles.Serum samples were taken in 41 IVF cycles at frequent intervalsfrom the beginning of ovarian stimulation until menstrual bleedingoccurred or a pregnancy was established. Concentrations of oestradiol,progesterone, placental protein 14 (PP14), pregnancy-specific1-glycoprotein (SP₁), and pregnancy-associated plasma proteinA (PAPP-A) were determined in the serum samples using commerciallyavailable (steroid) or purpose-developed (protein) immunoassays.The cycles were retrospectively distributed into four outcomegroups: (i) fertilization failure (FF, n = 8); (ii) implantationfailure (IF, n = 10); (iii) ‘interaction’ (embryo-endometrium)cycle (IC, n = 14), and (iv) clinical pregnancy (CP, n = 9).The embryo-endometrium interaction was detected by a rise inSP₁ in 23 cycles (70% of embryo transfers) at a time when endogenousHCG was still masked by external support. Early (‘false’)positive SP₁ concentrations were observed in two out of eightand five out of 14 cases in groups FF and IC respectively, butnever amongst the ongoing pregnancies (CP). PAPP-A did not distinguishpregnancy from the other outcomes. The PP14/progesterone ratiowas lower, later in the cycle, in CP than in the other groups.We conclude that, while it is not possible to predict the outcomeof a given IVF cycle earlier than 2 weeks after embryo transfer,the hormonal patterns can be used to detect abnormalities (e.g.endometrial asynchrony) which may be useful for subsequent treatmentcycles in the same patient.