Do small for gestational age fetuses have placental pathologies?

Area of Science:

• Obstetrics and Gynecology
• Perinatal Medicine
• Pathology

Background:

• Small for gestational age (SGA) infants are not always associated with adverse outcomes, but their placental pathology remains unclear.
• Fetal growth restriction (FGR) and SGA are distinct conditions affecting fetal development, with differing placental implications.

Purpose of the Study:

• To investigate placental microvasculature and the expression of anti-angiogenic pigment epithelium-derived factor (PEDF) and CD68 in early-onset FGR, late-onset FGR, SGA, and appropriate for gestational age (AGA) pregnancies.
• To compare placental degeneration and molecular markers across these four pregnancy groups.

Main Methods:

• Analysis of placental samples obtained post-labor from four groups: early FGR, late FGR, SGA, and AGA.
• Hematoxylin-eosin staining for degenerative criteria.
• Immunohistochemical evaluation (H score) and mRNA levels of CD68 and PEDF.

Main Results:

• Early-onset FGR placentas exhibited the highest degeneration.
• SGA placentas showed significantly more degeneration than AGA placentas.
• Increased PEDF and CD68 expression (both protein and mRNA) were observed in early FGR, late FGR, and SGA groups compared to AGA.

Conclusions:

• SGA placentas display degenerative signs comparable to FGR placentas, despite SGA often being considered constitutional.
• These placental degenerative signs are absent in appropriate for gestational age (AGA) placentas.
• The findings highlight potential placental dysfunction in SGA pregnancies, warranting further research into underlying mechanisms.