I remember the fear that consumed me when I was pregnant with my second child. A relatively new mom to a toddler not yet two years old, I was just getting my groove in this motherhood journey.

I had read a lot of the books. I was starting to find a schedule that was manageable. My little boy was starting to really blossom: walking, first words, a growing personality… these were the days I’d been dreaming of for so long.

And amongst all these factors was an all-encompassing love that filled my whole heart. I never knew such love until I became a mama to this little miracle.

So where, exactly, would I make space in my heart for another living breathing human to enter? Because I believed with every cell in me that my heart was full. No vacancy. Not even a broom closet of space for another person.

Not to mention my brain, which was also at max capacity. It took me almost two years to read this little boy’s facial expressions, the color and texture of his poop, his different cries and now his gurgling jabber. I knew how long naps would last, how much food to make and how much soothing to calm a meltdown. I had it down to a science. How on earth could I keep these plates spinning when another child entered the picture. It all seemed so apocalyptic.

You would not believe what happened when my second child, another darling boy, entered my world. Beyond my greatest fears, my heart did not explode. Aside from my certainty the world would end, my love for my first child did not get moved, erased or compressed.

My heart simply grew.

It was the most natural adjustment in the world. One minute my heart was one size, the next minute—its size had doubled. All my worries were for nothing. My body, my heart and my love knew exactly how and when to shift and expand.

The parenting journey is an exciting, momentous, overwhelming time for first time mothers. And the heart is our strongest muscle for good reason… It will double in size with the birth of a sibling.

If only the brain would do the same. But I can assure you that you do learn to keep the plates spinning. You do learn to incorporate new facial expressions, new schedules, new bedtime routines. It’s a much slower process, guaranteed and a few plates will break in the adjustment. But while our heart is a mom’s strongest muscle, our brain is slightly slower to acclimate.

I’m pretty sure that’s where the expression “mom brain” was derived from. And it’s all par for the course on this motherhood journey.