The 37-year-old patient had already given birth to a set of fraternal twin boys after an in vitro fertilization procedure three years ago. But she and her husband wanted just one more child, so they underwent a single embryo transfer. At the initial ultrasound, they received shocking news—not one, but three embryos appeared brightly on the screen, identical triplets sharing a single placenta.

Such monochorionic pregnancies not only have the risks that come with any multiple gestation, such as a higher chance of premature birth, gestational diabetes, pre-eclampsia and anemia, but also their own specific risks, including problems that result from having a commingled blood supply on the placenta, such as twin-to-twin transfusion syndrome.

Aware of some of these risks after their earlier twins, the couple contacted the Johns Hopkins Multiple Gestation Clinic, says clinic director and maternal-fetal medicine specialist Linda Szymanski. “They were initially interested in reducing the pregnancy,” she explains.

With the clinic’s close relationship with the Johns Hopkins Center for Fetal Therapy, Szymanski arranged for the couple to be seen at nine weeks gestation by fetal therapy colleagues Ahmet Baschat and Jena Miller. After performing another ultrasound to evaluate the fetuses’ orientations, sizes and connections to the placenta, the team recommended that the patient continue the pregnancy. “A reduction would require an invasive procedure unique to monochorionic multiples that could be dangerous to the whole pregnancy,” says Miller. “We all decided to keep a close eye out for any complication that might arise.”

Every two weeks, the patient came for regular prenatal care appointments at Johns Hopkins, seeing either maternal-fetal medicine or fetal therapy specialists—or sometimes both—at each visit. “That way, we could screen, monitor and treat any complications that arose at the same time with the expertise of both groups,” Baschat says. “That type of comprehensive care exists at few centers anywhere in the world.”

The pregnancy proceeded smoothly until 23 weeks, when the patient contracted influenza, which landed her in the hospital for a few days, but eventually had a full recovery. But then, at 26 weeks, her care team noticed a few abnormal findings on an ultrasound that had the potential to be more serious and long lasting. One fetus’ sac had started to expand, showing an increase in amniotic fluid that suggested increasing blood volume. Eventually, through Doppler that tracked blood flow, the doctors diagnosed the fetuses with twin anemia polycythemia sequence (TAPS), a form of twin-to-twin transfusion syndrome. TAPS occurs when small caliber arteriovenous anastomoses join, allowing unequal blood flow among fetuses.

At 26 weeks, the fetuses had a reasonable chance of viability outside the womb, but they were also vulnerable to complications that can arise from prematurity. The only treatment for TAPS is fetal laser surgery to close off and separate the blood vessels—a potentially risky proposition for a triplet pregnancy. “Making the right decision was agonizing for the entire team, the patient and her family,” Szymanski says.

In the end, however, the consensus was to move ahead, with Baschat and Miller performing the surgery. As the fetuses recovered in the days afterward, repeated ultrasounds showed that it was a success. Blood volume among the triplets gradually normalized. At 34 weeks, on the same birthday as their older twin siblings, the babies—three boys—were delivered jointly by Szymanski and Miller, born healthy, with nearly identical weights and blood counts.

“At every turn, the patient and her family knew that they had an entire team caring for them,” Szymanski says. “It’s the kind of care we strive to deliver to every patient who comes through our doors.”