PRIOR Study (Pre-eclampsia Risk In Oocyte Recipients) - Investigating Matching, Biomarkers and Outcomes.

INTRODUCTION AND BACKGROUND Maternal age at conception has increased globally, leading to a higher proportion of pregnancies among women aged ≥35 years. In Denmark, the average maternal age at first birth has risen from 24 years in 1970 to 30 years in 2021. As female fecundity declines markedly after age 35, the need for assisted reproductive technology (ART) is increasing.

The success rate of ART using autologous oocytes decreases significantly after age 40, making oocyte donation (OD) a relevant option for women with diminished ovarian reserve or poor oocyte quality. OD was first introduced in 1984 to treat infertility due to premature ovarian failure and is now used for various indications including Turner syndrome, previous oophorectomy, gonadotoxic therapy, and certain genetic disorders.

OD has been legal in Denmark since 2007 and double gamete donation since 2018. Healthy women under 36 years can donate oocytes anonymously or non-anonymously. The number of OD procedures in Denmark has increased from 124 in 2011 to 2,782 in 2022, resulting in 756 deliveries in 2021. The rise is attributed to delayed motherhood, legal changes, and increased donor compensation.

Several studies have demonstrated that pregnancies following OD are associated with a higher risk of obstetric complications, including pre-eclampsia (PE), intrauterine growth restriction, preterm birth, cesarean section, placental abruption, and postpartum hemorrhage. The risk appears to be even higher in double gamete donation pregnancies. The mechanisms behind these associations remain unclear but are thought to involve immune maladaptation due to exposure to non-self paternal and donor antigens.

PE complicates approximately 3-8% of pregnancies and is defined as new-onset hypertension (≥140/90 mmHg) with proteinuria (≥300 mg/24 h) and/or signs of organ dysfunction after 20 weeks of gestation. Risk factors include prior PE, chronic hypertension, renal disease, diabetes, autoimmune disease, multifetal gestation, nulliparity, advanced maternal age, high BMI, long interpregnancy interval, and family history of PE.