Author(s): Wenstrom KD, Syrop CH, Hammitt DG, Van Voorhis BJ
OBJECTIVE: To determine the incidence of monochorionic twinning in pregnancies resulting from assisted reproduction technologies (ARTs).
METHODS: We reviewed our experience with 218 ART pregnancies achieved over 3 years. All patients underwent transvaginal ultrasound 26 and 36 days after oocyte retrieval. The presence of two yolk sacs or two fetal poles within one sac suggested monochorionicity, and was confirmed by follow-up ultrasound and placental pathology. The various ARTs were compared to determine if any method had an increased incidence of monochorionicity compared to any other method. Statistical analysis was performed employing Chi Square analysis.
RESULTS: The incidence of monochorionicity in all gestations was 3.2% (8 times background rate); among multiple gestations it was 9.8%. The rates of monochorionicity for each ART appeared similar.
CONCLUSION: The incidence of monochorionic twinning is increased in pregnancies resulting from ART. Careful ultrasound evaluation of such pregnancies for monochorionicity is strongly recommended, both for planning of prenatal care and when considering a multifetal pregnancy reduction procedure.