When she was pregnant, Ashley Grover Desmarais did not give much thought to vaccinating her child.
It hadn't occurred to her that she could do anything "out of the norm" until late in her pregnancy, when a friend posted on Facebook the reasons why her daughter was unvaccinated.
The post prompted her to do some research. Grover Desmarais, 30, discussed vaccination with her pediatrician, other friends and family, and read various books and articles on the subject. Ultimately, she settled on an augmented schedule: Her daughter, who will be 3 in June, and her son, almost 1, will be fully vaccinated by the time they're school age, but they are following a delayed timeline.
"Many of my other friends have also done augmented schedules for their children's vaccinations," said Grover Desmarais. "I think it's because there's more awareness, more research available, and we're all able to post our findings and experiences on social media."
Despite clear support from major medical groups in the United States, some parents grapple with whether to vaccinate their children according to the immunization schedule recommended by the Centers for Disease Control and Prevention. A new study, among the first to probe the social factors that affect parents' decisions, found that friends, family and health care providers play a huge role in what parents choose.
Researchers surveyed 196 first-time parents about who they discussed vaccination with, as well as the types of sources they consulted, including books, media outlets or research articles. One hundred twenty-six followed the nationally recommended vaccination schedule, and 70 did not. (The study, published in the journal Pediatrics on Monday, was based in Washington, a state that has one of lowest vaccination rates in the U.S.)
Nearly all the parents indicated they had what the researchers called "people networks" -- groups of individuals whom they consulted about vaccination. Parents who decided to delay vaccinations, who opted for only some vaccinations, or who decided against vaccination -- dubbed "non-conformers" -- tended to have slightly larger networks. They also tended to have significantly more non-conformers in their social circles.
On average, 72 percent of non-conformers' networks recommended against following the recommended vaccination schedule, versus only 13 percent of those in "conformers'" social networks. Overall, parents said that their partners were the most influential people in their networks, followed by doctors, family members and friends.
Parents who did not stick to the recommended vaccination schedule were also more likely to seek information from books, research articles and mainstream media outlets. But the variable that best predicted parents' choices was the number of people in their networks who advocated for something other than government recommendations.
"For the majority of the parents in this study, the decision came down to the percent of people in their networks saying, 'don't do this' in one form or another," study author Emily Brunson, a medical anthropologist with Texas State University-San Marcos, told The Huffington Post.
Brunson said it is unclear if the parents in the study knew whether they were going to vaccinate before having their babies, then constructed networks that reflected the decisions they made, or if the social networks influenced parents' choices.
"Are the networks driving the decisions, or are the decisions driving the networks?" she asked, adding that she hopes to tackle the question next in her research.
In the meantime, she said the study has a clear message for parents: Who they surround themselves with can have a significant impact on the decisions they make, as can what they say to family and friends.
"It, frankly, really does matter when you're having conversations with other people about vaccination," Brunson said. "It actually has a big effect."
That's something mom Ella Rucker, 40, takes very seriously. She chatted with friends and family about vaccination, and read stories about parents who were staunchly opposed to it, but Rucker ultimately decided it was important to follow the government guidelines. Though Rucker is certain it was the right decision for her 3-year-old daughter, she is careful about what she says to friends when they come to her for advice.
"I tell them what I did, and why it was right for [my daughter]," she said. "But I don't want to be responsible for what anyone else decides."