Pfizer Inc. researchers concluded last year that pregnant women taking Zoloft risked having babies with heart defects, according to evidence made public by a lawyer at the first trial of more than 1,000 lawsuits over the drug.

The May 2014 internal report on the antidepressant found that newborns of women taking the mood-altering drug were at risk of suffering congenital anomalies, according to a portion of the report presented by a lawyer for the mother of a boy born with a heart defect.

Families suing Pfizer over Zoloft contend the drugmaker ignored internal red flags about potential birth defects to protect billions in sales of the drug. Pfizer didn’t warn doctors or patients about the risk, said Joe Zonies, a lawyer for Logyn Pesante and his mother told jurors in state court in St. Louis.

New York-based Pfizer racked up about $2.6 billion in Zoloft sales in 2005, making it the most popular antidepressant on the market. Pfizer lost patent protection over the medication the following year and generic versions are now made by Roxane Laboratories Inc.

Pfizer’s lawyers countered in opening statements Thursday that the company properly tested the drug before putting it on the market and there are no credible studies showing Zoloft causes birth defects.

“The science has never even suggested that birth defects were caused by Zoloft,” said Beth Wilkinson, one of the company’s lawyers.

Pfizer Data

Pfizer said in an e-mailed statement that its reports to European regulatory authorities and the U.S. Food and Drug Administration confirm its review of safety data didn’t identify a “signal for congenital anomalies and that a comprehensive review of the literature did not support an association between use of Zoloft and birth defects, including cardiac anomalies.”

“Plaintiffs have taken a single statement in one document, summarizing the results of a few studies, out of context,” according to the statement.

The birth-defect allegations against Zoloft mirror claims against GlaxoSmithKline Plc over its Paxil antidepressant. The London-based drugmaker agreed in 2010 to pay more than $1 billion to settle more than 800 suits accusing the drug of causing birth defects.

Glaxo Fine

Glaxo also agreed to pay more than $3 billion to resolve criminal and civil allegations that it illegally promoted prescription drugs such as Paxil and failed to properly report safety data to regulators. The settlement included a criminal fine of almost $1 billion, prosecutors said.

Some researchers contend the class of antidepressants that includes Zoloft and Paxil has been found to pose a greater risk of heart and lung defects in newborns than other drugs used to address patients’ moods.

The Zoloft internal report was introduced into evidence during the testimony of Robert Cabrera, a doctor at a University of Texas institute that studies birth defects. Cabrera was hired by Pesante’s family to testify as an expert on the causes of such defects.

Cabrera told jurors his review of research on babies born with medical issues convinced him that Zoloft was clearly “a risk factor for birth defects, especially heart defects.”

Zoloft Study

A study published in the New England Journal of Medicine in 2007 found pregnant women taking Zoloft faced double the risk of having a child with a birth defect, he said.

According to Pfizer’s report, risks to newborns include atrial septal defect, congenital heart disease and growth retardation. Children with a septal heart defect must undergo surgery to close a hole in the wall of their heart.

Other risks according to the report include omphalocele, a condition in which a newborn’s liver and intestines wind up outside the body after birth. Infants with persistent pulmonary hypertension, another risk mentioned in the report, struggle to breathe because of high pressure in their lungs and the condition can be fatal.

Pesante, whose mother took Zoloft during pregnancy, had to undergo three open-heart surgeries to address multiple defects, according to court filings. The boy, now 11, still suffers from lingering problems tied to the defects, the lawyer added.

Families contend in court filings that Pfizer officials hid Zoloft’s birth defect problems so they could market the drug as superior to rivals’ mood medicines for pregnant women.

They contend the drugmaker should be held liable for failing to clearly warn doctors and patients that Zoloft posed an increased risk of birth defects in the drug’s label and promotional materials.

Aggressive Marketing

In court, Wilkinson acknowledged Pfizer aggressively marketed Zoloft while assuring jurors it included warnings about pregnant women’s use of the antidepressant in the drug’s warning label.

She also added that the U.S. Food and Drug Administration approved those warnings and has never ordered Pfizer to be more specific about the drug’s birth defect risks.

Pfizer’s attorney said none of the mother’s doctors had identified Zoloft as the cause of her son’s birth defects and experts say its impossible to know exactly what causes such problems.

“Sometimes, bad things happen to good people,” Wilkinson said.

The case is Pesante v. Pfizer Inc., 1222-CCO-2441, Missouri Circuit Court, 22nd Judicial District (St. Louis).