When I took my son to kindergarten, I had to face a hard reality. He's my last kid, and this is the last time I'll do this.

• I had a tough recovery after giving birth to my son, and he's my last child.
• It was tough for me to drop him off at kindergarten.
• Letting go of my kids and watching them grow up is difficult, even though it's necessary.

I thought I was ready for my son to go to kindergarten, as I've done this before. Six years ago, I already went through my first drop-off at elementary school with my daughter.

But the morning I walked my son to the open double doors of his new school and hugged him goodbye, it felt different. As I watched him wander down the hall between his two best friends, holding their hands, I realized he was the last one. It felt final.

For 10 years, my husband and I struggled with infertility and loss. We had my daughter after several rounds of fertility treatment with IVF. But it was not until the end of our journey that I realized we may only have one baby.

When we decided to try again less than two years later, it wasn't at all what we expected. We had several failed transfers and four recurrent pregnancy losses in a row. Just before we turned to surrogacy, I had my last IVF transfer, and this time, it worked.

My body knew how to grow a baby again, and that following year, my son was born. I was grateful. He was my lucky one, my last chance before someone else had to carry my baby, and it could have turned out much differently.

Recovery from my son's birth was difficult

Unfortunately, in the weeks that followed, I was met with more complications. Similar to when I had his sister in my first delivery, I had another postpartum hemorrhage (PPH), and this time, I almost died from blood loss. The World Health Organization states that PPH is the leading cause of maternal mortality, and it accounts for 70,000 maternal deaths each year.

The following days in the hospital were grueling, spending nights away from my newborn. My body ached to hold and feed him again, and I prayed I'd be OK. I recognized I was lucky, both to be alive and a mom again. It wasn't until a month after he was born, when I received an unexpected letter from my OB/GYN, that I realized my luck had run out.

At first, I was angry reading those words. "It's best if you do not try to have any more children," my doctor wrote. It was infuriating and devastating. I couldn't believe she would tell me this news via mail and not with a phone call or with an office visit.

But as the days passed, I understood better why she'd said it. My body had been through more than any person should ever have to endure. She explained numerous ways another pregnancy could be not only high-risk but fatal for me. My body could barely handle having two babies after years of struggling to become a mother. Trying to carry a third baby would be unthinkable.

Those first few weeks at home, I spent every second with my son. I stared at him for hours, stroking his soft, pale cheeks and checking to make sure he was breathing in the middle of the night. I did all the things I could to take care of him, but it felt harder this time. I became anemic, feeling lightheaded and unstable. My body struggled to recover; the bleeding was incessant, and I could barely walk. My husband helped until I could do it on my own.

When I finally gained strength, I went for my first stroller walk with my son. Similar to when I left the house for the first time with my daughter, it felt as though a piece of me was being ripped away, never to be put back again. He was out in the world, his own person, and my last baby.

I had to let go of him a little more each day, just as I'd done with my daughter. As a stay-at-home mom running my own business, I paused work for a few months. We snuggled as I nursed him in the mornings and then spent afternoons at the park. This cycle repeated each day, as though we were in a dreamlike state.

It wasn't until he went off to preschool that he didn't need me as much anymore. I was proud of him for becoming more independent and loved that we still had our quality time together. It was a perfect balance for what we both needed at the time. In the afternoons, we'd share a snack together, do naptime, and then go for a walk or scooter ride. It was our comfortable routine, and my whole life felt like it had finally come together.

This new phase is a difficult reminder

Another year passed, and we enrolled him in kindergarten, but I didn't expect it would be like a punch to the gut. It wasn't just about saying goodbye to him at the front door of school until pick-up time, it was a difficult reminder of what I could no longer have — carrying another baby. I'd no longer be able to swaddle another baby in my arms, caressing little fingers and toes.

Instead, we enter this new phase of life, where he'll be in school all day, growing and learning without me — just as my daughter has done. Letting go is difficult, more than I expected it to be.

Just before we left that morning, I drew a heart inside his hand and mine, a reminder that I was with him. No matter how far he goes, he can press it anytime he needs me. He smiled as we walked to the entrance, squeezing my hand before he left my side. It's a harsh reality, the abrupt ending of one phase, moving to the next.

Although it hurts to know this was my last kindergarten drop-off, I'm learning to do things on my own again. I'd forgotten what it feels like to put myself first. Perhaps this freedom means we're both growing as individuals. I guess that means I must be doing something right.