NEWS | February 29, 2016

Rare identical twins, sharing an amniotic sac, are born on Leap Year at UC Davis Medical Center


Josefina and Greg Walker, of Stockton, received a special Leap Year gift today – the birth of their identical, monoamniotic twin daughters, Isabella and Sofia, who were delivered this morning at UC Davis Medical Center at 32 weeks gestation.

Photo of Greg Walker
Greg Walker visits with his newborn daughter Sofia in the UC Davis Neonatal Intensive Care Unit.

Isabella and Sofia shared an amniotic sac in their mother’s uterus during gestation, a very rare condition that occurs in about 1 percent of all twin pregnancies in the United States. Monoamniotic twins are always identical, monochorionic (identical twins that share the same placenta) and are often termed monoamniotic-monochoronionic or “MoMo” twins.

"The surgery went very well," said surgical resident Megan Ash, who performed the cesarean section with attending surgeon Alison Breen this morning. "Mom and babies are doing fine."

"We feel blessed," said Gregory Walker, who spent time this afternoon with the babies in the Neonatal Intensive Care Unit at UC Davis Children’s Hospital. "The rarity of this particular type of twins is 1 in 40,000 to 1 in 65,000 births. We feel very special."

Complications of monoamniotic twins include the risk of umbilical cord entanglement and twin-to-twin transfusion syndrome (TTTS), which may cause one twin to receive the majority of nourishment, inhibiting the growth of the other twin. Twenty percent of monoamniotic twins die from complications of sharing the same amniotic sac.

Josefina Walker was transferred to UC Davis Medical Center from her local hospital in Stockton due to the high-risk nature of her pregnancy. She spent the past 45 days in the hospital, being monitored, for cord entanglement and sudden death. Josefina's care team observed the twins' fetal heart rate tracings for two hours, every two hours, for signs of fetal compromise.

UC Davis Medical Center offers a Fetal Health Program, with a dedicated team of obstetrical, neonatal and other specialists who can establish a coordinated treatment plan for high-risk pregnancies to benefit both mother and baby.