EP18.38: Double serological test values in first trimester screening in spontaneous pregnancies versus assisted reproduction techniques

To analyse the double serological test values in first trimester screening in spontaneous pregnancies versus by assisted reproduction techniques. Cross-sectional study between 2018 and 2023 at three obstetric ultrasound centres. The ultrasounds were performed by experts in maternal-fetal medicine and certified by the Fetal Medicine Foundation. We included patients with first trimester screening (11.5-14 weeks), adjusted risk for trisomy 21 >1:1000, singleton pregnancies, and availability of β-hCG and PAPP-A. An analysis was performed according to the nature of the variables. Significance was considered at p < 0.05 by the Mann Whitney U statistical test. 1899 patients were evaluated, of which 1241 (65.4%) met the inclusion criteria. The mean maternal age was 33.5 ± 4.6 years, and gestational age was 12.0 ± 0.4 weeks. Spontaneous pregnancies accounted for 94.4% (1172/1241) and assisted reproduction techniques for 5.6% (69/1241). The serological values of β-hCG were 29.5 IU/L (IR: 19.5 - 45.8) vs. 37.7 IU/L (IR: 22.6 - 60.2) (p: 0.015), and for PAPP-A it was 2.3 IU/L (IR: 1.5 - 3.6) vs. 1.7 IU/L (IR: 0.97 - 2.6) (p < 0.001), for spontaneous pregnancies and by assisted reproduction techniques, respectively. In our experience, there are statistically significant differences in the serological values of β-hCG and PAPP-A in pregnancies achieved through assisted reproduction techniques compared to spontaneous pregnancies.