Isabella and Sofia Walker could certainly expect some special attention when they emerged into the world this Feb. 29, and not just because they were preemies. They're also identical twins – a roughly 1-in-333 probability – and “leaplings” born on a Leap Day, which rings in at just a 1-in-1,500 chance.
Unfortunately the infants are incredibly unique in another way too: besides sharing a single origin egg to become identical twins, they also shared a single amniotic sac and placenta in mom Josefina’s uterus during gestation.
That makes them monoamniotic-monochorionic or “MoMo” twins, a condition that occurs in as few as 1 in 65,000 U.S. pregnancies – and includes heightened risk of deadly complications such as fetal strangulation or malnutrition.
When the girls emerged by Caesarian section at 32 weeks, their umbilical cords indeed showed the beginnings of knotting – but not enough to prevent them from being safe and healthy. Josefina had spent the past 45 days and nights as an inpatient at UC Davis Medical Center so that fetal health experts could keep close watch on her pregnancy and the twins.
At some points her care team observed fetal heart tracings for two hours every two hours, looking for signs of compromise.
“We just feel blessed,” father Greg Walker said after a recent follow-up appointment. “We’re very fortunate to get to this point and be able to have these beautiful little girls. It’s amazing.”
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Helping 'MoMo' twins
The UC Davis Fetal Health Program includes a team of obstetrical, neonatal and other specialists who can establish coordinated treatment plans for high-risk pregnancies such as monoamniotic-monochorionic twins.
In 2015 the hospital was also the Sacramento region’s first to add on-site fetal surgery to its offerings.
Doctors at Josefina’s Stockton-area hospital had referred her to UC Davis, where the UC Davis Fetal Health Program includes a team of obstetrical, neonatal and other specialists who can establish coordinated treatment plans for high-risk pregnancies. In 2015 the hospital was also the Sacramento region’s first to add on-site fetal surgery to its offerings.
UC Davis doctors admitted Josefina on the spot when scans confirmed no signs of a membrane separating the fetuses and their cords. Twenty percent of monoamniotic twins perish from complications of sharing the amniotic sac, such as umbilical cord entanglement. Another common complication, known as twin-to-twin transfusion syndrome, can give one sibling the majority of nourishment at the other’s expense.
“One way I explain MoMo twins to parents is that the placenta is the kitchen and the amniotic sac is the bedroom,” said David Schrimmer, a perinatologist/obstetrician and chief of Maternal-Fetal Medicine at UC Davis who helped care for the Walker twins. Schrimmer is a renowned expert on twins and multiple fetuses, who successfully delivered the first set of healthy, surviving sextuplets in California.
“If you have two people with two kitchens and two bedrooms, everyone will be happy. In this case they have one kitchen and one bedroom and they're sharing everything. In that case no one’s going to be nearly as happy.”
Guarding against the related perils requires careful electronic monitoring fetal of vital signs, blood flow, growth and other factors. For Josefina, that meant frequently interrupted rest and countless, difficult hours sitting still to avoid jostling the twins. Visits to the radiology department for medical imaging became almost akin to “field trips,” since at least they involved physical movement.
“There were times that I almost I thought ‘I can’t do this,’ but it was for the girls,” Josefina said. “I thought about them and stayed positive.”
To pass the time, she organized hundreds of family photos into nearly a dozen albums – and looked forward to the daily visits that Greg paid after days spent trying to focus at work.
“The staff and nurses were so wonderful – they’re so caring and compassionate,” Greg said. “Even the food service and environmental service workers, who don’t provide health care, would stop and talk to us or encourage us.”
Relief in sight
“In this case (the twin fetuses) have one kitchen and one bedroom and they're sharing everything. No one’s going to be nearly as happy.”
— David Schrimmer, M.D., perinatologist/obstetrician and chief of Maternal-Fetal Medicine at UC Davis
Relief, albeit somewhat temporary, came via C-section on the morning of Feb. 29. The infants had reached 32 weeks gestation – allowing them to abandon the dangers of the womb as soon as possible, while also giving them the best chance to thrive outside it.
Isabella emerged first, then Sofia.
“The cry is what got me,” Greg recalled “Getting to hear that first gasp and scream was a huge sigh of relief.”
“I was relieved – we did it and they’re going to be OK!” Josefina added. “They looked good and I was really happy. But I was still scared too, thinking ‘They’re preemies – what happens now?’ ”
The infants soon revealed episodes of sleep apnea, or halted breathing, which ultimately required a nearly one-month stay in UC Davis Children’s Hospital’s Level IV Neonatal Intensive Care Unit (NICU) for monitoring.
Then Josefina was hospitalized again when she suffered a stroke, a risk that some new mothers face because the blood clots more readily around pregnancy (especially after long periods of bed rest). She still experiences headaches, but no other lasting effects so far to date.
Exhausted but happy
Finally Greg and Josefina returned home from the hospital with their rare twins, born on the rarest of days. They were exhausted, nervous and happy.
“It was nice, but even that’s scary, taking them out of the hospital and away from the monitoring,” Greg said. “But each day gets a little better for me as they get bigger and stronger.”
So far the twins’ personalities outside the womb match those displayed inside; Isabella is passive and laid-back, while Sofia stirs and cries (albeit with a tiny smile).
“She’s the one who had to fight for everything in the womb,” Greg said. “So it makes sense.”