Induction of premature labor and delivery by allergic reaction and prevention by histamine H ₁ receptor antagonist

The purpose of this study was to determine whether type I hypersensitivity can induce preterm labor and delivery that may be prevented by the administration of an H ₁ receptor antagonist or a mast-cell stabilizer. At days 40 through 50 of gestation, ovalbumin-sensitized guinea pigs that had not been treated or had been pretreated with an H ₁ receptor antagonist (ketotifen) or a mast-cell stabilizer (cromolyn sodium) were challenged with either ovalbumin or saline solution. Nonsensitized guinea pigs were challenged with ovalbumin. The duration of gestation was significantly shorter in sensitized animals that were challenged with ovalbumin than in the other groups. Pretreatment with ketotifen significantly increased the duration of pregnancy in sensitized animals, compared with untreated animals. Cromolyn sodium had no effect. An allergic reaction can induce premature labor/delivery, and pretreatment with histamine H ₁ receptor antagonist can prevent it. These observations provide evidence of a novel mechanism of disease for premature labor and delivery.