Association between adverse obstetric history and perinatal outcomes in singleton and twin pregnancies: a...

This study aimed to understand how adverse obstetric history affects perinatal outcomes in singleton and twin pregnancies, and to determine whether a twin pregnancy is a risk factor for adverse outcomes among women with an adverse obstetric history.

This retrospective cohort study employed logistic regression to explore the relationship between adverse obstetric history, including spontaneous abortion (SAB), induced abortion (IA), and ectopic pregnancy (EP), and the occurrence of twin pregnancies. Multivariable analysis assessed the risk of adverse perinatal outcomes in both singleton and twin pregnancies among women with an adverse obstetric history. Clinical characteristics and outcome risks were compared between twin and singleton pregnancies with an adverse obstetric history. Additionally, the study investigated the association between the number of types of adverse obstetric history events and adverse perinatal outcomes in twin versus singleton pregnancies. Mediation causal analysis was then conducted to explore whether twin pregnancy mediated the relationship between adverse obstetric history and perinatal outcomes.

Among 17,180 pregnancies, 1,372 (7.99%) were twin pregnancies. After multivariable adjustment, the odds of twin pregnancies were 78% higher among women with a history of EP, while a history of IA was associated with a 49% lower odds of twin pregnancy. In singleton pregnancies, IA and EP were associated with a significantly increased risk of placenta accreta (OR: 1.29), placenta accreta with bleeding (OR: 1.62), fetal growth restriction (FGR) (OR: 1.87), and pelvic inflammation (OR: 1.69). In twin pregnancies, IA was associated with a significantly increased risk of gestational diabetes mellitus (GDM) (OR: 1.47), while EP was associated with a significantly increased risk of placenta previa (OR: 4.59) and placenta previa with bleeding (OR: 5.71). Compared with singleton pregnancies, twin pregnancies with an adverse obstetric history are associated with an increased risk of preeclampsia, FGR, intrahepatic cholestasis of pregnancy (ICP), preterm birth, and placenta previa with bleeding compared with singleton pregnancies. Specifically, the accumulation of three types of adverse obstetric history events is associated with a distinctly increased risk of GDM and placenta accreta with bleeding. Mediation analysis shows that twin pregnancy mediates the relationship between adverse obstetric history and adverse outcomes, with different mechanisms for IA and EP.

Twin pregnancy is associated with an increased risk of adverse perinatal outcomes in women with a history of induced or ectopic pregnancy and appears to partly mediate the association between these histories and adverse outcomes.