ECTOPIC PREGNANCY AFTER IN-VITRO FERTILIZATION IS CHARACTERIZED BY DELAYED IMPLANTATION BUT A NORMAL INCREASE OF SERUM HUMAN CHORIONIC-GONADOTROPIN AND ITS SUBUNITS

We studied the dynamics of serum human chorionic gonadotrophin (HCG) a nd its free alpha (HCG alpha) and beta (HCG beta) subunits in 49 early pregnancies achieved by in-vitro fertilization (IVF) and embryo trans fer. Of the 49 early pregnancies, nine were normal singleton pregnanci es, 11 were twin pregnancies, 11 were ectopic, eight ended in a clinic al (spontaneous) abortion and 10 ended in a preclinical abortion, The HCG, HCG alpha and HCG beta concentrations in serum were measured on d ays 12, 19 and 26 after embryo transfer, Most ectopic pregnancies coul d be distinguished from singleton (and twin) pregnancies on the basis of low HCG concentrations by 12 days after embryo transfer, but clinic al abortions could not be distinguished from singleton pregnancies, In general, the measurement of HCG alpha and HCG beta and the molar rati os of the various forms provided only marginal additional value to tha t obtained from HCG, but on days 19 and 26 after embryo transfer HCG a lpha was the most sensitive indicator of a normal pregnancy after IVF and embryo transfer. We conclude that in ectopic pregnancies the conce ntrations of HCG, HCG alpha and HCG beta increase as expected but 1,5 days later than in normal pregnancies, This appears to be the result o f a delay in implantation.