When I went for my first ultrasound, two sacs were clearly visible on the screen. In one sac, it was possible to detect a heartbeat, while the other was blurry and indistinct. "It happens sometimes," the technician explained, "that one twin implants a few days before the other. You need to come back in two weeks for another ultrasound." She smiled as we left, assuring us not to worry, wishing us "Mazal tov, mazel tov."

We would go from the parents of two children to the parents of fourOver the next two weeks, my husband and I slowly overcame our shock, and began to eagerly anticipate the arrival of twins. Overnight, our family would double in size. We would go from the parents of two children to the parents of four children in a single bound.

Unspoken between us, yet mutually shared, was the feeling that this felt just right. Having lost a baby at six months of pregnancy a year and a half earlier, there had always been the sense that something was missing, and now, what was missing would be restored.

We brainstormed about names. We began to check out ads for double strollers. Our family would no longer fit into a single taxi cab, we realized. We discussed whether we would tell our families, or just surprise them with the news when the time came.

My husband joked that he would call his parents and announce, "It's a boy." Then he would hang up, and ring back a few moments later. "It's a boy," he would announce again. "You told us already," they would respond. "I know. It's another one."

Happily contemplating the way our family was now growing on the fast track, I didn't honestly consider the second ultrasound as anything more than a technicality.

In the meantime, I learned all I could about the fetal development of twins on the internet. One thing I learned took my breath away. It was called the Vanishing Twin Syndrome, and as its name implies, it refers to the demise and subsequent disappearance of one twin. Just reading about it filled me with foreboding, but I chased the dread away, chiding myself for being too nervous.

Yet, two weeks later, my foreboding was confirmed. "I'm sorry," the same technician now informed me. "The second sac doesn't have a heartbeat and has not developed since the last ultrasound." In an instant, our twins became a single baby. Despite the brief time I had known about the twin, I mourned its passing. Where there had been life, there was no longer life.

A week later, late at night, I began to bleed. "Oh G‑d," I prayed. "Don't let me lose this baby. Write it in the Book of Life." I called my husband. "Stop whatever you are doing, and start praying," I told him. "I'm bleeding." The next morning, I went for my third ultrasound in just ten weeks. My baby lay curled up contentedly, and even performed a few acrobatics for its audience. I was reassured by seeing the steady heartbeat, the life form now the size of my thumb.

Even when there is seemingly nothing to do, there is always a final card to playThe second sac was still there, but it was smaller now. "The bleeding is probably the second sac breaking up," the technician informed me. She sent me to the doctor. "There is no way to tell, but let's hope the technician is right. In the meantime, rest and come back next week. If you start bleeding more heavily, go to the hospital."

My husband and I walked out of her office with a new prescription for medication, but no guarantees. There was nothing to do but wait. Yet, for a Jew, even when there is seemingly nothing to do, there is always a final card to play. That's a clear sign to turn to the Source.

That week, the books of life and death lay open. Yom Kippur was just two days away. The rabbi I consulted advised me to stay in bed all day, and fast. He gave me specific instructions on what medical symptoms would be considered grounds for breaking the fast.

I rested in bed while I fasted and prayed, standing up only for one of the most intense and powerful prayers, the silent Amidah prayer. As the day drew to a close, I gathered my strength and took my older children to the synagogue for the last wrenching minutes of prayer.

As the gates of prayer were slowly closing, the praying intensified, culminating in a final passionate declaration of G‑d's oneness. "Hashem hu ha'Elokim," the congregation called out, declaring that the G‑d of kindness and the G‑d of judgment are one.

Into this spiraling arc of prayer, I cast my own heartfelt prayer that this tiny life, the sole survivor of what were almost twins, would develop to grow healthy and strong, and we would merit this new addition to our family.

Yom Kippur ended with a certain sense of relief. I knew that I had been heard, that I had done my best. I had completed the fast, and though I was physically weak for the next few days, I felt spiritually strong and connected. During the intermediary days of Sukkot, about two weeks later, I returned for another ultrasound. Everything was fine.

And it was. I had made peace with the twin that wasn't meant to be, and could open my heart to the little survivor, who had fought alongside me, and who had merited to be written into the Book of Life.