Jennifer just wanted a sibling for her daughter. Then she discovered she had "secondary infertility".

If you’re looking for advice about options surrounding fertility, pregnancy or counselling, always consult your doctor.

I was on Clomid for a year, trying to get pregnant with my daughter before my then-new fertility doctor ordered a round of tests and suggested an IUI.

It worked the first time out. Phew, I thought. Well, at least we’ll know what to do next time around.

Cut to two years after my girl’s arrival and I’m once again at my fertility doctor’s office, feeling a bit smug with the knowledge that not only do we already know how to deal with my PCOS, but that we could almost set baby No. 2’s birth date.

Secondary infertility had other ideas.

The first, second, then third IUI failed (the fourth one too,) each bringing with it a round of blood tests, injections and office procedures that would lead to prayers, pregnancy sticks and increasing depression as another try tanked.

I was working full-time and parenting a precocious two-year-old whose growth had pushed us out of our tiny apartment to a new place that included a bedroom of her own. My husband and I were happy—and lord knows, kids are expensive, even more so in New York City. Plus, I was in my late 30s.

Maybe fate was telling us something.

And yet, I wanted my girl to have a sibling. My husband has a brother and I have two. For me, having someone to say, "Mum's crazy, right?" or "Want to go in on a present for Dad?" was fundamental.

But maybe also selfish? I knew women who were having trouble getting pregnant for the first time. I had a beautiful healthy baby already. Why should I get two?

It's an internal script that is the special stress of secondary infertility.

First, you’re caught off guard. (I got pregnant before!)

But then, your stress is hidden by the fact that you already have a baby, so few friends assume there's any trouble.

And as an added bonus, you feel a sharp sense of guilt for your desire for more than the healthy baby you already feel lucky enough to have. Indeed, some parents dealing with secondary infertility face criticism for wanting to go to extremes to have more children.

Listen: How do you come to terms with losing a baby? Olympian Libby Trickett shares how she made it through the sadness (post continues after audio...)

I never experienced any criticism, if only because I never talked about it. The only person who knew was my husband, who was living through his own stress as each cycle launched and failed.

Thank goodness for the web. I became addicted to blogs written by women going through the same thing. They didn’t know it, but their essays were my support group.

And so, the cycles kept failing until about a year in, my fertility doctor said it was time to consider IVF, the pricey approach that still doesn’t guarantee success. But before that, we’d try one more IUI.

I had to travel for work during the cycle. I remember packing my injectables in a cooler and taking them with me on my flight. After my team retired for the night, I slipped down to the front desk to get more ice to keep everything cool.

The whole thing was a hassle, but I was nothing if not committed. For while the other rounds had been covered by insurance, this last one was costing us money—and IVF would cost so much more. A difficult conversation was just around the corner for my husband and me.

I came home to an acupuncture appointment. (It had helped with my first pregnancy.) My husband was running late, but I just couldn’t miss it, so I lay on the table with my toddler on my chest as the needles went in. To his credit, the acupuncturist just rolled with it and my girl enjoyed my best storytelling.

Weeks later, the pregnancy stick showed positive. I cried and my husband may have too.

I held my breath at the fertility doctor a few days later as I waited for him to confirm the news, then walked on eggshells for three months as I waited for the go-ahead to return to my regular OB-GYN.

When my sleepy baby arrived, I knew right away that he was the missing member of our family—and 10 years later, with middle school looming, I can’t imagine what we’d be without him.

It had taken a lot to get him here, but we're always so glad he came.