Previous prelabor or intrapartum cesarean delivery and risk of placenta previa.

The purpose of this study was to examine the association between previous cesarean delivery and subsequent placenta previa while distinguishing cesarean delivery before the onset of labor from intrapartum cesarean delivery. We conducted a retrospective cohort study of electronic medical records from 20 Utah hospitals (2002-2010) with restriction to the first 2 singleton deliveries of nulliparous women at study entry (n=26,987). First pregnancy delivery mode was classified as (1) vaginal (reference), (2) cesarean delivery before labor onset (prelabor), or (3) cesarean delivery after labor onset (intrapartum). Risk of second delivery previa was estimated by previous delivery mode with the use of logistic regression and was adjusted for maternal age, insurance, smoking, comorbidities, previous pregnancy loss, and history of previa. Most first deliveries were vaginal (82%; n=22,142), followed by intrapartum cesarean delivery (14.6%; n=3931), or prelabor cesarean delivery (3.4%; n=914). Incidence of second delivery previa was 0.29% (n=78) and differed by previous delivery mode: vaginal, 0.24%; prelabor cesarean delivery, 0.98%; intrapartum cesarean delivery, 0.38% (P<.001). Relative to vaginal delivery, previous prelabor cesarean delivery was associated with an increased risk of second delivery previa (adjusted odds ratio, 2.62; 95% confidence interval, 1.24-5.56). There was no significant association between previous intrapartum cesarean delivery and previa (adjusted odds ratio, 1.22; 95% confidence interval, 0.68-2.19). Previous prelabor cesarean delivery was associated with a >2-fold significantly increased risk of previa in the second delivery, although the approximately 20% increased risk of previa that was associated with previous intrapartum cesarean delivery was not significant. Although rare, the increased risk of placenta previa after previous prelabor cesarean delivery may be important when considering nonmedically indicated prelabor cesarean delivery.

Downes KL ，Hinkle SN ，Sjaarda LA ，Albert PS ，Grantz KL ... -  《-》

The risk of abnormal placentation and hemorrhage in subsequent pregnancy following primary elective cesarean delivery.

Chen S ，Cheng W ，Chen Y ，Liu X ... -  《-》

The association of placenta previa with history of cesarean delivery and abortion: a metaanalysis.

Ananth CV ，Smulian JC ，Vintzileos AM 《-》

Risk Factors for Severe Postpartum Hemorrhage After Cesarean Delivery: Case-Control Studies.

Butwick AJ ，Ramachandran B ，Hegde P ，Riley ET ，El-Sayed YY ，Nelson LM ... -  《-》

In vitro fertilization as an independent risk factor for placenta accreta spectrum.

Placenta accreta spectrum is well known for its association with catastrophic maternal outcomes. However, its pathophysiology is not well defined. There have been emerging data that in vitro fertilization may be a risk factor for placenta accreta spectrum. We investigated the hypothesis that in vitro fertilization is an independent risk factor for placenta accreta spectrum. A retrospective analysis of all deliveries in a prospective, population-based cohort (2012-2019) was performed in a tertiary academic center. Primary outcome variable was placenta accreta spectrum. Univariate analysis was performed on potential risk factors for predicting placenta accreta spectrum, and a multivariate model was designed to best fit the prediction of placenta accreta spectrum adjusted for risk factors such as cesarean delivery, placenta previa, age, and parity. History of previous cesarean delivery was known as a risk factor for both placenta previa and placenta accreta spectrum; hence, the interaction between "placenta previa" and "previous cesarean delivery" was included in the final model. Odds ratios were calculated as exponential of beta coefficients from the multivariate regression analysis. A total of 37,461 deliveries were included in this analysis, 5464 (15%) of which had a history of cesarean delivery, 281 (0.7%) had placenta previa in their index pregnancy, and 571 (1.5%) had in vitro fertilization pregnancy. The frequency of placenta accreta spectrum was 230 (0.6%). Independent risk factors for placenta accreta spectrum were in vitro fertilization pregnancy (adjusted odds ratio, 8.7; 95% confidence interval, 3.8-20.3), history of previous cesarean delivery (adjusted odds ratio, 21.1; 95% confidence interval, 11.4-39.2), and presence of placenta previa (adjusted odds ratio, 94.6; 95% confidence interval, 29.3-305.1). After adjustment for number of previous cesarean deliveries, the correlation persisted for in vitro fertilization (adjusted odds ratio, 6.7; 95% confidence interval, 2.9-15.6). Our data suggested that in vitro fertilization is an independent risk factor for placenta accreta spectrum, although its relative clinical importance compared with that of the presence of placenta previa and history of cesarean delivery is small. The pathophysiology behind this relationship remains to be investigated.

Salmanian B ，Fox KA ，Arian SE ，Erfani H ，Clark SL ，Aagaard KM ，Detlefs SE ，Aalipour S ，Espinoza J ，Nassr AA ，Gibbons WE ，Shamshirsaz AA ，Belfort MA ，Shamshirsaz AA ... -  《-》