The current study compared triple serum screening results and outcomes in 37 oocyte donation (OD) and 46 self oocyte IVF-conceived singletons of similarly aged women (28.8 +/- 4.4 years and 30.7 +/- 4.5 years respectively). Both groups were followed from their embryo transfer and throughout pregnancy. Although the daily pattern of first-trimester serum beta-human chorionic gonadotrophin (HCG) was similar in both groups, higher mid-gestation HCG serum concentrations were found, i.e. 1.38 and 1.32 multiples of the median (median MoM) for IVF and OD respectively, in comparison with 0.99 median MoM from the same reference laboratory. Only the OD group had significantly increased alpha fetoprotein (AFP) concentrations (1.45 median MoM) (P = 0.002) compared with the reference laboratory. A total of 11% of the IVF and 13% of the OD women were found to be screen positive. In neither group were chromosomal abnormalities detected and no fetal or neonatal deaths were recorded. Seven (15%) of the OD and seven (19%) of the IVF women had an adverse obstetric outcome. Of those cases, six IVF and four OD women had serum HCG > or = 1.2 MoM and five OD women had AFP >1.2 MoM. Therefore, in those pregnancies the high serum HCG concentrations may alert for adverse obstetric outcome rather than indicating a high risk for Down's syndrome fetuses.