The incidence of adverse pregnancy outcomes has remained high in recent years, which poses a serious threat to maternal and neonatal life and health. Chronic stress is known to be a risk factor for adverse pregnancy outcomes, while the relationship between allostatic load (AL) as a composite physiological index of chronic stress, and adverse pregnancy outcomes has not been clarified.

To explore the effect of AL on adverse pregnancy outcomes in women in late pregnancy.

Women in late pregnancy who met the study requirements were recruited as study subjects by using the convenience sampling method from November 2021 to November 2022 in the obstetrics outpatient clinics of the 901 Hospital, Joint Logistic Support Force of the Chinese People's Liberation Army, Jin'an Maternal and Child Health Care Hospital. Basic information such as general and obstetric data were collected through questionnairs, biological indicators were collected through physical examination and laboratory tests, and AL scores of the study subjects were calculated by referring to AL-related literature; pregnancy outcome information was obtained by reviewing the hospital electronic medical record system. Multivariate Logistic regression analysis was used to explore the effect of AL on adverse pregnancy outcomes in women in late pregnancy.

A total of 354 women in late pregnancy with an average age of (29.3±4.1) years and upper quartile of AL total score of 3 were included in this study. The upper quartile of the total AL score of the study subjects was used as the high-risk threshold, and they were divided into low-level AL (AL <3) and high-level AL (AL ≥3) according to their AL scores. High AL pregnant women accounted for 32.8% (116/354) and low AL pregnant women accounted for 67.2% (238/354). The prevalence of adverse pregnancy outcomes was 15.5% (55/354), including 9.9% (35/354) of macrosomia, followed by preterm birth〔5.4% (19/354) 〕and low birth weight〔2.3% (8/354) 〕. The incidence of adverse pregnancy outcomes was higher in women in late pregnancy with high AL (26.7%, 31/116) than in women in late pregnancy with low AL (10.1%, 24/238) (P<0.05) ; the incidence of preterm birth (10.3%, 12/116) and delivery of macrosomia (15.5%, 18/116) was higher in women in late pregnancy with high AL than in women in late pregnancy with low AL (2.9%, 7/238; 7.1%, 17/238) (P<0.05). Multivariate Logistic regression analysis showed that women in late pregnancy with high AL had a 2.465-fold increased risk of adverse pregnancy outcomes compared to women in late pregnancy with low AL〔95%CI (1.315, 4.622), P<0.05〕. High AL level was a risk factor for preterm birth〔OR=4.832, 95%CI (1.545, 15.114) 〕and delivery of macrosomia〔OR=2.868, 95%CI (1.392, 5.909) 〕in women in late pregnancy compared to low AL level (P<0.05) .

High level of AL in women in late pregnancy increase the risk of adverse pregnancy outcomes, especially the risk of preterm birth and delivery of macrosomia. Attention to AL in women during pregnancy should be enhanced to provide a theoretical basis for preventing adverse pregnancy outcomes.