Mono mono twins occur about once in every 10,000 pregnancies, but a second set in one week has been born at the same Ohio hospital. The rare “monoamniotic” babies share a single placenta and amniotic sac while in the womb. Akron General Hospital’s director of maternal and fetal medicine Dr. John Stewart said the odds of two sets of mono mono twins being born at the same hospital is probably as high as one in 10 million.
The second set of twins, born May 15 to 24-year-old Amanda Arnold, are baby girls weighing less than four pounds each. JaNiya and Amaya McCall were born at 32 weeks gestation by Caesarean section and taken to the Neonatal Intensive Care Unit (NICU) at Akron Children’s Hospital where they will remain for several weeks while they grow bigger and stronger. Stewart says that mono mono twins are typically scheduled for early delivery between 32 and 34 weeks to avoid complications such as entanglement in each other’s umbilical cords, which cuts off the supply of blood to each other. Arnold had been on bed rest at the hospital for a month before the delivery so that the babies’ blood supply could be closely monitored.
JaNiya and Amaya were born just one week after Sarah Thistlethwaite gave birth at the same Ohio hospital to mono mono girls Jenna and Jillian, who caught attention not only because of the rarity of their birth, but because they were born holding hands. Jenna weighed 4 pounds, 2 ounces, Jillian weighed 3 pounds, 13 ounces. The babies were on ventilators for about a week after their birth, which was also by Caesarean section.
Mono mono twins like the two sets born last week in Ohio are a variation on identical twins. Unlike fraternal twins, which result from two eggs fertilized by two sperm, identical twins come from one egg from the mother which is fertilized by one sperm from the father, forming an embryo that splits into two fetuses early in development. Normally the identical twins share a placenta, but have two separate amniotic sacs, leading to what are called monochorionic diamniotic (mono di) twins. Monochorionic monoamniotic, or mono mono twins, come from an embryo that splits after the formation of the amniotic sac, resulting in a shared sac as well as a shared placenta. This happens in about 1 percent of identical twins.
Ultrasound usually picks up the unusual mono mono condition, and mothers diagnosed by a regular ultrasound machine are typically referred to a high-risk specialist for a higher quality ultrasound to confirm it. Besides originating in a rare form of development, the Ohio babies are exceptional for surviving high-risk pregnancies with many possible health hazards that can be life threatening. In addition to cord entanglement, mono mono twins are at risk for birth defects, premature birth, and twin-to-twin transfusion syndrome (TTTS) which occurs when one twin gets the majority of nourishment in the womb. The fetuses in a mono mono twin pregnancy have a mortality rate of about 50 percent.
As in the most recent Ohio twin birth to Amanda Arnold, mothers pregnant with mono mono twins typically enter the hospital after the 28th week of pregnancy for constant monitoring, which can substantially lower the risk of fetal death. JaNiya, Amaya, Jenna, and Jillian, are four babies who have beaten very high odds to make their dramatic entrances into the world.
By Beth A. Balen