Raleigh, N.C. — To get the shots or not to get the shots – that's the dilemma many parents face when they suspect their child is at risk of developing problems from immunizations.

A little more than 99 percent of children get their recommended immunizations in North Carolina. Fewer than 1 percent of parents opt out for religious or medical reasons.

However, there are indications that one in every 150 babies born in this country will develop autism, and some parents say they believe there's a link to vaccines, so they're reluctant to have their children immunized.

From the start, Chris and Kelly Steffens closely tracked their oldest daughter's development. Marly, 5, was born seven weeks premature. They followed their doctor's advice, including vaccinations.

At age 2 she was diagnosed with autism, characterized by social difficulties, language abnormalities, narrow interests and ritualistic behavior.

"My husband and I kind of suspected vaccines may have something to do with it," Kelly Steffens said.

That was why they watched their second daughter, Skylar, now 22 months old, more closely as she got her shots.

Similar behaviors popped up, especially after her third dose of DTaP vaccine, or diphtheria, tetanus and acellular pertussis, when she was 12 months old.

"I decided right then and there that there was going to be no more vaccines," Kelly Steffens said.

"Unfortunately, some of the signs and symptom of autism do tend to show up around the time that children are receiving some shots," said David Laxton, communications director with the North Carolina Autism Society.

Suspicions surround thimerosal, a mercury-based preservative once used in many vaccines, but it hasn't been available for children under 6 since 2003. Still, research continues to show no link to autism.

"Despite the fact these vaccines no longer contain thimerosal, actually the rates of autism have continued going up," said Dr. David Weber, a UNC infectious disease specialist.

He says the benefits of immunization far outweigh the risk. In fact, immunization is listed as one of the 10 greatest health achievements of the 20th century.

"We've eliminated polio from North and South America. We've gone from 20,000 cases of congenital rubella – a horrible disease – just to a single case. [And] 800,000 cases of measles to under 100 cases in the U.S.," Weber said.

But the Steffenses said they still believe their girls are at risk from something in the vaccines.

"[Marly] was premature. Her immune system was not fully developed as it was. These children are getting 24 immunizations or more before they're 24 months old," Kelly Steffens said.

Laxton, with the NC Autism Society, concedes studies show thimerosal might not be the cause, but the advocacy group supports parents' desire to work with pediatricians and their schools.

The state requires full immunization as children enter kindergarten.

"See what options are for maybe spacing things out and putting them on a different schedule," Laxton said.

The Steffenses said they might consider immunizations in the future, but not in combination vaccines, just one immunization at a time.

"Spread them out and watch them carefully and see how they do," Kelly Steffens said.

The Steffenses said a gluten-free diet and special developmental therapy have helped their daughters.

“[Skylar’s] really doing great. She's very verbal. She's very social,” Kelly Steffens said.

Public school systems in the state accept both religious objections to vaccination and genuine medical reasons. For medical concerns, the parents take a form from the school nurse to their child's pediatrician.

The form requires the doctor to check boxes on the forms that apply, such as a specific medical allergy or other medical contraindications. If the reason is not listed on the form, the doctor needs to write about it in detail.

You can obtain a full recommended schedule for immunizations from the Centers for Disease Control and Prevention. More information is available about the Autism Society of North Carolina, too.