A unique placenta previa risk factor profile for pregnancies conceived with assisted reproductive technology

Objective: To define specific risk factors for placenta previa in pregnancies conceived with assisted reproductive technology (ART).

Design: Retrospective cohort.

Setting: Fertility centers and inpatient obstetric units in Massachusetts.

Patient(s): Patients conceiving with ART and delivering at 20 weeks gestation or later between 2011 and 2017 in Massachusetts.

Intervention(s): Patient demographic and medical factors and specific components of their cycles. Data were obtained by linking vital records of the State of Massachusetts to reproductive clinic data obtained from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System, and then supplementing this information with laboratory and obstetric data from 2 large academic hospitals.

Main outcome measure: Associations were tested between multiple cycle- and patient-related factors and placenta previa or low-lying placenta at delivery. After testing for confounders, multivariate models were adjusted for maternal age, history of prior cesarean delivery and birth plurality, and are reported as adjusted relative risks (aRR).

Result(s): We included 18,939 pregnancies, with 553 (2.9%) having placenta previa at delivery. Advanced maternal age (aRR, 1.25; 95% confidence interval [CI], 1.06-1.48), endometriosis, (aRR, 2.22; 95% CI, 1.71-2.86), and controlled ovarian hyperstimulation (aRR, 1.33; 95% CI, 1.12-1.59) were associated with placenta previa, whereas multiple births (aRR, 0.63; 95% CI, 0.48-0.81) and a history of polycystic ovary syndrome or ovulation disorders (aRR, 0.59; 95% CI, 0.46-0.75) had negative associations. The endometriosis association was strong in nulliparas and the controlled ovarian hyperstimulation association was strong in parous patients in a stratified analysis. No association was seen with prior history of cesarean delivery.

Conclusion(s): Patients conceiving with ART do not have the typical previa risk factors of prior cesarean delivery and multiple gestations, whereas endometriosis and fresh embryo transfers contributed moderate risk. The embryo transfer process itself may affect previa development in this population.