Angiogenic growth factors in maternal and fetal serum in concordant and discordant twin pregnancies.

OBJECTIVE

To assess soluble fms-like tyrosin kinase 1 (sFlt-1), free vascular endothelial growth factor (f-VEGF) and the f-VEGF/sFlt-1 quotient in twin pregnancies, and to determine if they are impaired in discordant twins.

METHODS

Case-control study between 18 discordant and 46 concordant twin pregnancies. Angiogenic growth factors were measured in maternal serum during pregnancy and in umbilical artery and vein at birth.

RESULTS

Discordant twins were more often conceived by assisted reproductive techniques than concordant twins. Maternal plasma f-VEGF was significantly lower in discordant twins (p = 0.04). F-VEGF and f-VEGF/sFlt-1 in the whole sample show a significant higher level in concordant twins. When we analyzed umbilical cord angiogenic factors, the smaller twin had a lower f-VEGF/sFlt-1 quotient (p = 0.01). We found no correlations between maternal or umbilical growth factors and placental or fetal weight. No difference was found in veno-arterial levels of angiogenic factors in each twin; however, there was a significant rise in arterial f-VEGF (p = 0.06) in discordant twins.

CONCLUSION

Mothers of discordant twins have a more anti-angiogenic environment compared to those of concordant twins. We also found an anti-angiogenic environment in the small twin when we compared umbilical vein angiogenic factors against its big co-twin.