Additive effect of factors related to assisted conception on the reduction of maternal serum pregnancy-associated plasma protein A concentrations and the increased false-positive rates in first-trimester Down syndrome screening

1. Bellver, J.
2. Casanova, C.
3. Garrido, N.
4. Lara, C.
5. Remohí, J.
6. Pellicer, A.
7. Serra, V.