Facebook is aggressively being used by anti-vaccination advocates to target pregnant women with sponsored advertisements to spread false information and conspiracy theories as the US battles a climbing measles outbreak.

A sponsored ad found by Quartz journalist Jeremy Merrill shows the anti-vaccination organisation Stop Mandatory Vaccination targeting women ages 20 to 60 who have expressed interest in pregnancy living in the state of Washington – where the governor recently declared a state of emergency over the measles outbreak.

Nearly 50 children and young adults in Clark County, Washington have become sickened by the disease since January.

According to the CDC, there have been over 100 instances of measles since January – more than the entire year of 2016, when there were only 86. So far, nearly every child who has gotten ill is un-vaccinated.

In the sponsored ad by Stop Mandatory Vaccinations, which has over 100,000 likes on Facebook, it said a woman's daughter died "12 hours after being injected by eight vaccines in 2008."

Vaccination rates have plummeted in pockets of the Pacific Northwest in recent years, as lies about the dangers of vaccines have spread, despite the fact that the measles vaccine is safe for almost everyone and can prevent many debilitating illnesses and death.

Facebook sent Business Insider the following statement:

"We are committed to accurate and useful information throughout Facebook. We remove content that violates our Community Standards, downrank articles that might be misleading, and show third-party fact-checker articles to provide people with more context. We have more to do, and will continue efforts to provide educational information on important topics like health."

A Daily Beast report said there are nearly 150 anti-vaccine advertising spots run by 7 Facebook pages targeting women over the age of 25.

The ads have been viewed between 1 and 5 million times, according to the report. The data was collected by Pay Dirt's Lachlan Markay.

In response to Markay's reporting, Representative Adam Schiff, the Democrat from California, sent a letter to Google CEO Sundar Pichai and Facebook CEO Mark Zuckerberg to express concern over the "information that discourages parents from vaccinating their children" that has run rampant on each's platforms.

This article was originally published by Business Insider.

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