Monochorionic Triplet Gestation after in Vitro Fertilization

Transabdominal ultrasound (US) at 35-day posttransfer showed monochorionic triplets, each with a heartbeat [Figure 1]a.{Figure 1} The first and second pregnancy trimesters proceeded smoothly, but one fetus demonstrated intrauterine distress at 33 weeks of gestation, and three normal baby boys were born at the 33rd week of gestation by cesarean section. [3],[4] Although the mechanisms whereby assisted reproductive technology increases the incidence of MZT remain unclear, an increased incidence of monozygotic multiple pregnancies has been associated with advanced maternal age, ovulation induction, certain IVF culture conditions and prolonged culture, zona pellucida (ZP) micromanipulation such as intracytoplasmic sperm injection, assisted hatching, and FET. [5] The mechanisms may involve hardening of the ZP as a consequence of extended exposure to the culture medium, leading to the development of multifetal plates during blastocyst hatching; an effect of the culture medium on the junctions of the inner cell mass, leading to monochorionic multiple gestations; or manipulation of the ZP triggering splitting of the blastocyst and formation of MZTs through the hole in the ZP during blastocyst expansion.