(Bloomberg) -- Dozens of lawsuits are challenging the long-standing belief that pregnant women can safely take acetaminophen, an over-the-counter drug used in Tylenol and generic pain medications. 

Women have filed 87 complaints in seven states against sellers of store-branded pain relievers, including Walmart Inc., CVS Health Corp. and Walgreens Boots Alliance Inc. Citing new studies linking the drug to increased risk of developmental issues in babies, the plaintiffs blame their children’s autism, attention-deficit problems or hyperactivity on significant doses of acetaminophen taken during pregnancy. 

While the women say they should have been warned of the risks, the companies dispute the claim acetaminophen may harm fetal development. And some doctor groups, including the American College of Obstetricians and Gynecologists, insist the medication is safe to take during pregnancy, saying the research is inconclusive and found no direct relationship to neurodevelopmental disorders.

Makers and sellers of acetaminophen “should have paid greater attention to the growing research linking it to developmental issues,” said Melissa McEvoy, a 42-year-old plaintiff in California who says she took acetaminophen to treat headaches when she was pregnant with her son. The boy is now 11 and on the autism spectrum. “There should always be the information presented, the potential risks, so that you can make an informed decision for yourself.”

In an emailed statement, Walmart spokesman Randy Hargrove said the company “does not manufacture these products. We expect suppliers to provide safe and quality products that comply with all applicable laws, including labeling requirements.” Representatives of CVS and Walgreens declined to comment on the suits. 

Combining Claims

So far, the legal fight represents a small fraction of the millions of pregnant women who have taken the medication. But lawyers for the plaintiffs on Thursday asked a panel of federal judges in St. Louis to consolidate the suits in the multi-district litigation (MDL) case so they can share information and schedule test trials. The panel will rule later on the request, which is opposed by the companies. 

“It’s too early to say whether the claims expose the named companies to any significant risk,” said Holly Froum, a litigation analyst at Bloomberg Intelligence. “I think proving these claims could be challenging.”

But one member of the panel in St. Louis, US District Judge Matthew Kennelly from Chicago, said during the hearing Thursday there was the potential for many more claims given how many pregnant women rely on acetaminophen to deal with pain. “This could get really gigantic,” he said.

Rise in Autism

For years, doctors recommended acetaminophen as the safest way for women to deal with aches and pains in pregnancy. The most common alternative, ibuprofen, isn’t usually recommended for use during pregnancy. Obstetricians estimate as many as 65% of US women take acetaminophen at some point during pregnancy -- there were 3.6 million births in 2020 -- along with 50% of women world-wide. 

That means there may be hundreds of thousands of potential plaintiffs over acetaminophen, said Mikal Watts, a lawyer for some plaintiffs who wants the suits consolidated in federal court in northern California. “This will be one of the largest multi-district litigations” in US history, he said in court filings. “It’s a monumental undertaking.” 

Autism is one of the fastest-growing US childhood ailments, affecting 1-in-44 8-year-olds, though researchers aren’t sure why. Attention disorders, including hyperactivity, also are on the rise, showing up in more than 9% of kids ages two to 17. The US Center for Disease Control and Prevention found the rate of development disabilities in kids between three and 17 jumped more than 17% over a two-year period beginning in 2015.

Watts and other lawyers are bringing the suits now because they say the science behind the link between acetaminophen and autism-spectrum ailments has firmed up over the last decade. There are more than 20 peer-reviewed studies affirming the link between significant use of the drug and development problems, they said. A 2018 study published in the American Journal of Epidemiology identified a 20% jump in the risk of autism when mothers use high rates of acetaminophen during pregnancy, plaintiffs said. 

“And despite what the defense may say, this isn’t junk science,” said Ashley Keller, a lawyer representing women in the case. “It’s taken some years for the science to catch up, but we are there now.” 

‘Safe Pain Relievers’

The research isn’t conclusive, however. According to a statement last year by the American College of Obstetricians and Gynecologists, acetaminophen remains “one of the only safe pain relievers” for pregnant women. 

Studies so far “show no clear evidence that proves a direct relationship between the prudent use of acetaminophen during any trimester and fetal developmental issues,” the ACOG said. “Neuro-developmental disorders, in particular, are multi-factorial and very difficult to associate with a singular cause. The brain does not stop developing until at least 15 months of age, which leaves room for children to be exposed to a number of factors that could potentially lead to these issues.”

Emily Oster, a Brown University economist who has written books about data and parenting decisions, said that while there are legitimate questions being raised by new research, the studies are a long way from proving acetaminophen causes developmental ailments.

Until there are randomized, controlled studies comparing groups of pregnant women who take the medication and those who don’t, “it really doesn’t help us decide that question either way,” Oster said.

For now, the lawsuits are targeting sellers of store-brand medications rather than Tylenol maker Johnson & Johnson, the world’s largest maker of health-care products. 

Jim Murdica, a lawyer for the drug retailers, told the judicial panel on Thursday “it would be manifestly unfair” to consolidate the lawsuits against them when none of the more than 600 manufacturers of acetaminophen have yet been sued. 

Expanding Claims

But Watts, the plaintiffs lawyer, told the panel that will change once the claims against the retailers are organized, which will clear the way for lawsuits against manufacturers including J&J.

“The health and safety of the people who use our products is our top priority and we always recommend consumers carefully read and follow the label when using any over-the-counter medication,” Melissa Witt, a J&J spokeswoman, said in an emailed statement. She added Tylenol’s label warns woman “if pregnant or breastfeeding, ask a health professional before use.”

Tylenol -- along with Band-Aid bandages and Listerine mouthwash -- falls under J&J’s consumer-products division, which is being spun off into a separate company, which also would serve as a potential funding source for J&J’s separate litigation over cancer claims tied to its now-withdrawn baby powder.  

“The plaintiffs may want to see how that bankruptcy and the spin off shake out before they sue J&J,” said Elizabeth Burch, a University of Georgia law professor who teaches about mass torts and MDLs. “Everybody knows the makers of Tylenol will get sued over this. It’s just a question of when.”

That consumer unit plays a key funding role in a controversial bankruptcy case involving J&J’s liability over the talcum powder cases, Burch said. An appeals court is weighing whether that Chapter 11 case should be thrown out. Should that happen, juries would once again hear talc-cancer claims against J&J, leaving it facing legal and financial uncertainties. 

The case is In RE: Acetaminophen-ASD/ADHD Products Liability Litigation, MDL, No. 3043, US Judicial Panel on Multi-District Litigation (St. Louis) 

(Updates with comment from Walgreens and J&J.)

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