Health Law Daily Wrap Up, FOOD—N.D. Ill.: Mother’s specific causation testimony survives in infant formula-induced NEC bellwether case, (Feb 24, 2026)

By Pankhuri Bhatnagar, B.A. LL.B.

A formula maker’s challenges to the expert’s lack of experience in dealing with infants suffering from the subject disease and her other alleged failures went to the weight, rather than admissibility, of the evidence.

In a multidistrict litigation brought against the manufacturer of a preterm infant formula that allegedly caused necrotizing enterocolitis (NEC) and led to the death of infants, a federal district court in Illinois denied the manufacturer’s motion to exclude a specific causation expert in a bellwether case. The court held that the physician properly applied a differential etiology by ruling out other potential causes of the illness and concluding that the formula at issue caused an infant’s NEC. Discussion of overlapping general causation analysis factors and reliance on her own medical experience rather than existing medical literature did not affect the reliance of her methodology (Inman v. Mead Johnson & Co., LLC, No. 22 C 3737 (N.D. Ill. Feb. 17, 2026)).

Background. A month after his birth, a premature infant was fed Mead Johnson’s cow’s-milk-based preterm infant formula while in the neonatal intensive care unit (NICU). The infant developed NEC and died shortly after. The decedent’s mother sued the formula manufacturer, Mead Johnson & Company (MJC). The instant case became part of a consolidated Multidistrict Litigation proceeding involving hundreds of similar claims, and is one of four bellwether trials. The manufacturer moved to exclude the testimony of the mother’s specific causation expert pursuant to Fed. R. Evid. 702 and Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).

Expert evidence. The expert was a board-certified neonatologist and Associate Professor of Pediatrics at Stanford who practiced at Children’s National Medical Center in Washington, D.C. She had almost 15 years of experience as a pediatric physician, practiced exclusively in the NICU since 2019 where she regularly made feeding decisions, cared for tens of thousands of premature infants over the course of her career, and assessed and treated between 50–100 babies diagnosed with NEC. She was tasked with examining the decedent’s medical records to determine whether MJC’s Enfamil Premature Formula caused him to develop NEC. For this purpose, she conducted a differential diagnosis to evaluate and rule out other potential causes and contributing factors of the infant’s NEC.

Bradford Hill challenge. MJC did not challenge the expert’s qualifications, but claimed that she improperly applied the Bradford Hill criteria—typically used for general causation—rather than a true differential etiology, and further contended she misapplied those factors. The court disagreed. Although the expert referenced Bradford Hill concepts such as temporality, biological plausibility, and dose-response, those considerations overlapped with a specific causation analysis. The mere reference to Bradford Hill factors did not convert her analysis into a general causation opinion or render her methodology unreliable, especially since a differential etiology is an acceptable, reliable method for establishing legal cause. Schultz v. Akzo Nobel Paints, LLC, 721 F.3d 426, 433 (7th Cir. 2013). The physician properly ruled out various factors that could have caused the infant’s NEC based on her extensive clinical experience, relevant medical literature, and review of the infant’s medical records. The court was satisfied that her opinions would be helpful to a jury in determining the cause of the illness.

Clinical reliance. The manufacturer next attacked the physician’s alleged overreliance on her clinical experience and her limited citation to medical literature, pointing out that she had treated no more than 100 infants with NEC and was unsure whether any of them had developed the disease as a result of exposure to formula. The court held that the physician’s reliance on her training and extensive experience to fill gaps in medical literature did not render her methodology unreliable. Moreover, other experts in the MDL would address general causation through literature-based analysis, and the physician permissibly relied on those conclusions when forming her specific causation opinion. Given the rarity of the disease even within the population of preterm infants, the physician’s comparative lack of experience with babies who developed NEC after consuming formula was not surprising. The court clarified that lack of experience was a basis for cross-examination, not for exclusion of her testimony.

Other challenges. Arguments concerning the brevity of her report, the veracity of her medical conclusions, her prior statements related to other infants, and her failure to address certain publications were deemed to be issues of weight and credibility suitable for a jury. The court concluded that the expert had employed a sound and reliable differential etiology and that her opinions would be helpful if general causation is established. Accordingly, the court denied Mead Johnson’s motion.

The case is No. 22 C 3737.

Judge: Pallmeyer, R.

Attorneys: Jose M. Rojas (Levin, Rojas, Camassar & Reck LLC) for Alexis Inman and Shannon E. Hall. Anthony J. Anscombe (Steptoe LLP) for Mead Johnson & Co. LLC and Mead Johnson Nutrition Co. Bridget Kathleen O'Connor (Jones Day) for Abbott Laboratories and Abbott Laboratories, Inc. d/b/a Abbott Nutrition. Garrett L Boehm, Jr. (Johnson & Bell, Ltd.) for Children's National Medical Center.

Companies: Mead Johnson & Co. LLC; Mead Johnson Nutrition Co.; Abbott Laboratories; Abbott Laboratories, Inc. d/b/a Abbott Nutrition; Children's National Medical Center

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