Do placentae of term singleton pregnancies obtained by assisted reproductive technologies differ from those of spontaneously conceived pregnancies?

The study was conducted to investigate the association of placental morphological and histopathological features with term, singleton pregnancies obtained by assisted reproductive technologies (ART). The study group comprised 45 consecutive women with a singleton pregnancy, obtained by ART, who delivered at term. For each subject in the study group, the consecutive, matched-for-age-and-parity woman, with a term singleton, spontaneously conceived pregnancy served as the controls. The placentae of both groups were subject to a detailed morphological and histopathological investigation by one pathologist, who was blinded to specimen origin. Pregnancy complications, fetal weight and perinatal outcome were similar in both groups. No differences in morphological or histopathological features of the placenta were observed between the groups. Nevertheless, the placentae of the study group showed a borderline, significantly higher placental weight and placental:fetal weight ratio, and placental thickness was significantly higher. Abnormal umbilical cord insertion was significantly more prevalent in the study group. Neither the specific ART method employed, nor the infertility factor affected the results, suggesting that multiple embryo transfers and/or ovulation induction protocols may account for these differences.