For the Puentes, there is no doubt that their twins felt pain at birth.

At birth, they didn’t have the strength to cry or squirm or even grimace, Melissa said. But she soon came to recognize signs of discomfort in their facial muscles, especially in the eyelids. When they were at ease, she said, “their eyelids are smooth and facial muscles are relaxed.” But after surgery their muscles tightened and their eyelids appeared stressed. “It was obvious he was in pain,” she said of one son.

The pain markers went well beyond facial cues. Even routine blood draws or IV insertions could cause measurable reactions.

“You saw a spike in blood pressure and heart rate, and a drop in blood stats and oxygen stats,” Ian said.

The Puentes’ observations of facial expressions and stress measures mirror techniques used by medical professionals to judge pain in premature infants and fetuses in the womb. These “surrogate measures” are needed since a newborn preemie or an unborn fetus cannot express itself, cannot even vocalize or even squirm.