A baby is born every six seconds in the United States. Just minutes after the umbilical chord is severed and the thick coating of amniotic fluid is wiped from their red and purple splotched skin, these infants are given their very first shot, a vaccine for hepatitis B.

It’s true that immunizations like this one have saved thousands of lives since the very first mass inoculations just after World War II, but a growing concern regarding the possible side effects of new vaccines like hepatitis B has mounted in recent years. Many parents are convinced that there may be a link between thimerosal, the mercury-based preservative found in some vaccines, and autism. This has led to a nationwide rise in unvaccinated children.

Though the federal government and the Centers for Disease Control and Prevention (CDC) have denied any scientific correlation between vaccines and autism, Dr. Mady Hornig, from the Mailman School of Public Health, Columbia University, and other critics point to evidence that suggests otherwise. One such statistic, and probably the biggest motivating factor in why many new parents are reconsidering immunizing their children, is that autism cases have increased substantially in past few decades. One in 10,000 children developed autism in the 1970s, whereas today, as many as one in 150 children develop the disorder, according to a Web site provided by Vaccine Awareness of North Florida.

Hornig’s research involved injecting a group of mice with tissues similar to those found in children with mercury-laden vaccines equivalent to the doses children received in the 1990s. The mice developed serious brain problems.

“I’ve decided not to have my child vaccinated for anything yet. I just keep hearing about this risk and that risk…it’s scary. I just don’t know enough about them,” said Holly Baker, mother to a 4 and half-month-old baby girl.

Thirty years ago, this was barely a concern for parents.

“When I was pregnant with my first child, I had never even heard of autism. We were mostly concerned with major birth defects…things like that,” said Sue Murphy, mother of four children born in the ‘70s.

According to the CDC, thimerosal has been used in many vaccines since the 1930s and no convincing scientific evidence of harm caused by the low doses of this mercury-containing compound has ever been documented. However, in July 1999, the Public Health Service agencies, the American Academy of Pediatrics and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure.

Parents have the option to choose vaccines that do not contain thimerosal, but they have to know about the option before they can ask for it.

“My pediatrician has a poster on the wall in the waiting room that lists the vaccines that contain mercury and the ones that don’t,” Baker said. “The pediatrician I had for my first child didn’t do this. There’s no way I would have known otherwise.”

Choosing not to have children vaccinated, however, isn’t easy. All public schools require proof of immunizations for admittance, though parents can apply for an exemption. Depending on the state, exemptions can include medical, religious, and philosophical objections. The majority of these fall into the religious category. Since many states do not require parents to expand on the specific religious practice that clashes with the vaccination, some parents may use this exemption to simply circumvent the system.

International travel also presents an issue. Children and adults alike are required to have proof of immunizations in order to obtain a passport and travel to foreign countries. Very few, if any, exemptions apply here.

There are also concerns for those who choose not to have children vaccinated.

According to pediatrician Dr. Karena Neri, unimmunized children are more likely to get vaccine-preventable diseases if there is an outbreak than those who have been immunized. If an unimmunized child gets a vaccine-preventable disease, he or she is likely to spread that disease to another unimmunized child.

Reported cases of the measles, a disease that has been almost completely eradicated since the vaccine was first administered in the 1960s, have more than doubled in 2008.

“Vaccines like the MMR (measles, mumps, rubella) are good because they help prevent dangerous diseases. If someone were to contract the measles, the chance for brain damage alone is 50 percent,” Neri said.

Other vaccines, such as those for chicken pox, might not be such a good idea, as Neri pointed out. When a child contracts chicken pox, his or her body builds immunities to the virus that will provide protection for life. If a child is vaccinated for chicken pox, he or she must come back every 10 years for a booster shot. If the booster is forgotten, the person runs the risk of contracting the disease and health risks associated with the
chicken pox for adults are much greater than for children.

“The benefits for getting children immunized far, far outweigh the potential risks,” Neri said. “As a general rule, parents should have their children vaccinated.”

Change has followed the passing of recent years, and with it, the idea of immunizing children.

“When women my age were having children, the grandmothers would describe the symptoms and the deaths of children who weren’t vaccinated,” Murphy said. “We all immunized our children. Today, it’s just different.”