A new study published by the American Academy of Pediatrics has found that vaccine refusal by parents is on the rise. Pediatricians who had encountered at least one child patient with parents against vaccinations grew from 74.5 percent to 87 percent between 2006 and 2013. So why do so many parents decide not to vaccinate their children? Special-needs teacher Kristen O’Meara, 40, of Chicago, tells The Post’s Jane Ridley why she was staunchly anti-vax until she had a frightening wake-up call.

Doubling up in pain, my 3-year-old twins, Áine and Lena, screamed out in unison as agonizing cramps raged through their tiny stomachs.

My older daughter, Natasha, then 5, was equally stricken — dehydrated and desperately sick.

All three of my kids had rotavirus, the potentially deadly form of diarrhea that could so easily have been prevented if I’d gotten them vaccinated.

The guilt was overwhelming. But I thanked my lucky stars that they were neither newborn babies nor medically fragile, the type of children rotavirus can snatch from this world in a heartbeat.

At that moment, as my husband, Frank, now 40, and I battled the horrible illness ourselves, I began to doubt the anti-vaccine stance I shared with many of my highly educated friends. I’d been raised in a “crunchy” family that questioned authority and the status quo. So, when Natasha was born in February 2010, I entered motherhood with what I thought was a healthy skepticism regarding vaccination.

Purposely seeking out anti-vax books and websites that cited links between vaccines and rising rates of allergies, asthma and ADHD, I scared myself to death reading the (since debunked) report by Andrew Wakefield about the MMR (measles, mumps, rubella) inoculation causing autism.

And I found a local pediatrician who agreed not to vaccinate Natasha. Two years later, I stuck to my guns and refused all inoculations for my twins.

I got absorbed in the anti-vax culture and secretly thought of myself as being superior to others. Parents who vaccinated didn’t have my special investigative skills. As far as I was concerned, they didn’t stop to question and were just sheep following the herd.

Speaking of herds, I knew that the great reduction in diseases had a good deal to do with clinical vaccinations. I just thought: “Let someone else take on the risks of vaccinating.” It was a very selfish viewpoint because I had the best of both worlds. I knew that my daughters had a low risk of contracting vaccine-preventable diseases — precisely because vaccination is effective. I had faith in herd immunity while questioning its very existence.

Although I wouldn’t admit it — especially to my best friend, who shared my anti-vax stance — I had mixed feelings about that fact.

Then, in March 2015, we were struck by the rotavirus. I’ll never forget the look of fear on my daughters’ faces as they suffered intense pain and diarrhea that lasted for three weeks. I’ve no idea where we picked it up, but the horrific experience proved that, even living in a highly vaccinated population, we were vulnerable. Thankfully, we pulled through with a combination of rest and rehydration.

I thought, ‘Let someone else take on the risks of vaccinating.’ It was a very selfish viewpoint. - Kristen O’Meara

After that, a series of events forced me to reconsider my stance. There was the publicity surrounding the terrible outbreak of measles at Disneyland in California, which got me thinking about my choices. Next, in the spring of 2015, we got a letter from the preschool where I desperately wanted to send the twins. They were no longer admitting children who had not been vaccinated. I’d managed to get Natasha in by signing a religious-exemption letter, even though that wasn’t the real reason. I thought to myself: “Do I really want to spend my life writing these letters — fighting something I’m not even sure I believe in anymore?”

Then I started researching the intentional bias of the anti-vax reports. I wondered what would happen if I looked for confirmation of the efficiency and safety of vaccination. I read several books by Paul Offit, the co-inventor of a lifesaving rotavirus vaccine — who’s an indispensable purveyor of truth — as well as “The Panic Virus,” a logical, comprehensive argument for vaccines by Seth Mnookin.

In June of last year, I finally let go of so much fear. Armed with a new perspective and tons of information, I switched pediatricians and was able to trust that vaccinating my girls was the right thing to do. With my consent, she put them on an aggressive catch-up schedule. They are now fully vaccinated.

Sadly, I lost my best friend over the issue. When I shared with her that I’d changed my mind, there was an instant feeling of tension. Our relationship didn’t immediately end, but it went downhill from there. Perhaps she thought I was judging her.

Now I’m the most confident and proud about my decision I’ve ever been. That’s the reason I wrote to the pro-vax advocacy group Voices for Vaccines, which featured my story on its website. I’m frustrated with the amount of misinformation I encountered when I set out on this journey. But in the end I am thankful, for the sake of Natasha, Áine and Lena, that I was able to reassess my position and accept information that is based on well-established, sound scientific evidence.

If I can make even one anti-vaxxer think twice, speaking out will have been worth it.

Recently, an Australian mother posted a viral video on her 5-week-old baby battling whooping cough, also in an attempt to educate parents on the importance of vaccinations.

Video Source: Facebook/Sandra Tee via Storyful