This prospective observational case-control study aims to compare placental expression levels of progesterone membrane receptors, including PGRMC1, PGRMC2, and PAQR family receptors, between pregnancies complicated by intrauterine growth restriction (IUGR) and uncomplicated healthy pregnancies. Placental tissue samples obtained at delivery will be analyzed using quantitative real-time polymerase chain reaction (qRT-PCR). The study also aims to investigate the association between receptor expression levels and perinatal outcomes in order to better understand the role of progesterone membrane receptors in the pathophysiology of IUGR.

Intrauterine growth restriction (IUGR) remains one of the leading causes of perinatal morbidity and mortality. Although placental insufficiency is considered the major underlying mechanism, the molecular pathways responsible for impaired fetal growth are not fully understood.

Progesterone is essential for maintaining pregnancy and exerts its biological effects through both classical nuclear receptors and membrane progesterone receptors. Among these, progesterone receptor membrane component-1 (PGRMC1), progesterone receptor membrane component-2 (PGRMC2), and members of the progestin and adipoQ receptor (PAQR) family have recently attracted attention because of their roles in placental development, angiogenesis, immune regulation, and maintenance of placental integrity.

The present study will prospectively recruit women diagnosed with IUGR and healthy pregnant women delivering at the same institution. Placental samples collected immediately after delivery will undergo molecular analysis using quantitative real-time PCR to determine receptor expression levels. Clinical and obstetric characteristics together with neonatal outcomes will be recorded prospectively.

The findings may contribute to a better understanding of the molecular mechanisms underlying placental dysfunction in IUGR and may identify potential biomarkers associated with adverse pregnancy outcomes.

Inclusion Criteria:

Singleton pregnancy Maternal age 18-45 years Diagnosis of IUGR according to institutional criteria

Exclusion Criteria:

Multiple pregnancy Major fetal structural anomaly Chromosomal abnormality Congenital infection Maternal chronic systemic disease Autoimmune disease Chronic hypertension Pregestational diabetes mellitus Placental abruption Intrauterine fetal demise

Pregnant women aged 18-45 years delivering at Samsun Training and Research Hospital will be enrolled. The study population will consist of women with singleton pregnancies complicated by fetal growth restriction (FGR) and healthy pregnant women with appropriate fetal growth serving as the control group. Placental tissue samples will be collected immediately after delivery for molecular analysis.