A Missouri judge has ordered Abbott Laboratories and Reckitt Benckiser unit Mead Johnson to face a new trial over allegations that they failed to warn a mother about the risks of their specialized baby formulas for premature infants,

Back in October, a jury found North Chicago-based Abbott and Reckitt’s formula subsidiary Mead Johnson not responsible for a baby developing necrotizing enterocolitis, or NEC, from their cow-milk-based formulas. NEC is a serious, and sometimes deadly, gastrointestinal disease that primarily afflicts premature infants.

The ruling overturned a previous verdict related to an infant formula case and has implications for both Abbott and Reckitt, with the latter’s shares also falling by 4.5%. The legal battle revolves around the Whitfield case, which pertains to the alleged link between infant formula and necrotizing enterocolitis (NEC) in premature infants.

Abbott Laboratories and Reckitt Benckiser Group Plc shares fell as a judge ordered a new trial after rejecting a verdict that had cleared the companies of liability over claims they hid potential risks of their premature-infant formulas.

Reckitt said on Friday a U.S. circuit court has ruled that a new trial could be sought by plaintiffs in a case that had accused the London-listed firm and Abbott of failing to warn of the risks of premature baby formulas.