First trimester biochemical screening for Down's syndrome in singleton pregnancies conceived by assisted reproduction

BACKGROUND: Serum biochemical markers [free beta hCG (f beta hCG); pregnancy-associated plasma protein-A (PAPP-A)] used in first trimester Down's syndrome screening have not been fully investigated in pregnancies achieved by assisted reproduction techniques. We present data on pregnancies conceived by all types of assisted reproduction techniques, including pregnancies following ovum donation (OD) and a large sample by ICSI. METHODS: First trimester Down's syndrome screening was performed in 1054 normal singleton pregnancies: natural conception (n=498), ovulation induction (OS, n=97), IVF (n=47), ICSI (n=222) and OD (n=190). RESULTS: No differences in maternal levels of f beta hCG and PAPP-A, measured by the Kryptor system, appeared between naturally conceived pregnancies (n=498) and those obtained with assisted reproduction techniques (n=556). Several differences were apparent when comparing f beta hCG levels between different technologies but PAPP-A levels only differed between OS and IVF pregnancies (P < 0.05). In a further small study, no differences were observed using frozen embryos (n=37), preimplantation genetic diagnosis (n=53) or sperm from testicular biopsy (n=21). CONCLUSIONS: Data accumulated so far suggest that first trimester biochemical markers either do not need any adjustments (e.g. in pregnancies obtained after OS and ICSI), or have very little impact (e.g. IVF pregnancies) or no impact (e.g. OD pregnancies) on the false positive rates.