Evidence that difference in size of fraternal twins may originate during early gestation: a case report.

Abstract

We describe a woman who conceived by in vitro fertilization (IVF) and embryo transfer (ET). Transvaginal ultrasound demonstrated at least 1 week's difference in size of twin gestations from 1 month post-transfer of embryos to delivery. Differences in sac size, crown-rump length, and gestational growth are discussed, as are implications of ultrasound in early pregnancy.