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,

Infant formula makers Abbott and Reckitt saw their stocks decline Friday after a judge ruled plaintiffs could pursue a new trial against the companies.

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.

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.

Missouri 22nd Judicial Circuit Court Judge Michael Noble granted the plaintiff's motion for a new trial on Thursday, citing the “widespread misconduct” of defendants Abbott Laboratories Inc. and Mead Johnson.

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 Benckiser is moving forward with the sale of its nutrition operations housing the Mead Johnson infant-formula business.