First trimester serum angiogenic/anti-angiogenic status in twin pregnancies: relationship with assisted reproduction technology

BACKGROUND The risk of pre-eclampsia (PE) increases in twin pregnancies, especially when assisted reproduction technologies (ART) are used. The aim of this study was to assess angiogenic/anti-angiogenic factors in maternal serum in the first trimester of twin pregnancies and establish if the mode of conception influences angiogenic status. METHODS This prospective study enrolled women with twin (n = 61) and singleton (n = 50) pregnancies. Dichorionic twin pregnancies were divided into two groups according to their mode of conception. Singleton pregnancies were used as the control group. Soluble fms-like tyrosine kinase (sFlt-1), free placental growth factor (PlGF) and soluble endoglin (sEng) concentrations were measured in the first trimester maternal serum. RESULTS In the first trimester, women with twin pregnancies had higher serum concentrations of the anti-angiogenic factor sFlt-1 than that with singleton pregnancies (3924 ± 250 versus 2426 ± 162 pg/ml, respectively; P < 0.001). Maternal serum PlGF concentrations were lower in singleton pregnancies than those in twin pregnancies (37 ± 3.7 versus 59 ± 5.6, respectively; P < 0.001). Serum concentrations of sFlt-1 were higher in twin pregnancies conceived by ART than those in spontaneous twin pregnancies (4313 ± 389 versus 3522 ± 300 pg/ml, respectively; P < 0.05). No differences between groups were observed for sEng. CONCLUSIONS In the first trimester, twin pregnancies conceived using ART showed a heightened anti-angiogenic status that could explain the increased risk of PE in these cases.