Relationship between prior pregnancy loss and subsequent adverse pregnancy outcomes in women

Pregnancy loss is a prevalent issue among women of childbearing age and can have significant physical and psychological consequences for patients and their families. However, the association between the number of previous pregnancy loss and the risk of adverse pregnancy outcomes (APOs) in subsequent pregnancies remains uncertain. This study aimed to provide clinical data to determine whether the number of previous pregnancy loss increases the risk of APOs in women with a history of pregnancy loss. We conducted a cohort-based, nested case-control study involving 1074 women with a history of pregnancy loss. Detailed demographic and medical history information was collected at baseline, and biological specimens were retained for laboratory testing. APOs were selected as the primary outcome, with cases defined as individuals who experienced any APO events. Cases were matched with event-free control subjects at a 1:2 ratio. Using conditional logistic regression, we examined the relationship between the number of previous pregnancy loss and APO events, using age at first pregnancy as the reference exposure. Among the study participants, we identified 358 cases with APO events and 716 controls. The occurrence of APOs was found to be associated with an increased number of previous pregnancy loss exposures compared to controls without APOs, with an odds ratio (OR) of 1.36 and a 95% confidence interval (CI) of 1.14 to 1.61. This association persisted even after adjusting for patient demographics, the total number of previous pregnancies, and other exposures, with an adjusted odds ratio (aOR) of 1.75 and a 95% CI of 1.28 to 2.4. Furthermore, our study also indicated that age at first pregnancy within a certain range may be a risk factor for APOs. In conclusion, our findings suggest that an increased number of previous pregnancy loss is associated with a higher risk of APOs in subsequent pregnancies among women with a history of pregnancy loss. These results provide valuable clinical data and underscore the importance of considering the number of previous pregnancy loss when assessing the risk of APOs in this population. Additionally, age at first pregnancy may also play a role in APO risk. Further research is warranted to better understand the mechanisms underlying these associations and to develop appropriate interventions to mitigate the risks associated with pregnancy loss.