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Open Access Full Text Article  Research Article

Histopathological Evaluation of Placental Changes in Women with Excessive Gestational Weight Gain

Özkan Yükselmiş, Murat Akkuş *, Fırat Aşır 

Department of Histology and Embryology, Medical Faculty, Dicle University, 21280, Sur, Diyarbakır, Turkey

 

 

INTRODUCTION

Pregnancy is a dynamic physiological process requiring complex maternal adaptations to support fetal growth and development¹. The placenta plays a central role in this process by mediating nutrient exchange, gas transfer, metabolic regulation, and immunological tolerance between the mother and fetus ². Preservation of placental structural integrity is therefore essential for optimal pregnancy outcomes. In recent decades, excessive gestational weight gain and maternal obesity have emerged as major public health concerns³. These conditions have been linked to increased risks of gestational diabetes, hypertensive disorders, cesarean delivery, and long-term metabolic disease in offspring⁴. Growing evidence suggests that maternal metabolic stress adversely affects placental development, leading to morphological and functional abnormalities⁵.

Histopathological studies have reported that excessive maternal weight gain may be associated with villous immaturity, increased fibrin deposition, stromal edema, vascular congestion, and altered trophoblastic morphology⁶. Such changes can impair uteroplacental blood flow and compromise fetal oxygen and nutrient delivery⁷. However, detailed histomorphological evaluations focusing exclusively on routine H&E findings remain limited⁸.

Therefore, the present study aimed to investigate placental histopathological changes associated with excessive gestational weight gain using Hematoxylin–Eosin staining, providing a structural basis for understanding placental dysfunction in this population.

MATERIALS AND METHODS

Study Population and Tissue Collection

This study was conducted at Dicle University Faculty of Medicine, Department of Obstetrics and Gynecology. Placental tissues were collected from women aged 18–40 years following delivery. The control group consisted of 45 normal-weight pregnant women (BMI <30 kg/m²), while the study group included 45 women with excessive gestational weight gain/obesity (BMI ≥30 kg/m²). Pregnancies complicated by systemic diseases, gestational diabetes, preeclampsia, infection, or other obstetric complications were excluded.

Placental samples not required for routine pathological diagnosis were collected immediately after delivery for histological analysis.

Histological Processing and Hematoxylin–Eosin Staining

Placental tissue samples were fixed in 10% neutral buffered formalin for 24 hours, followed by routine dehydration, clearing, and paraffin embedding. Serial sections of 4 µm thickness were cut using a microtome and mounted on glass slides. Standard Hematoxylin–Eosin staining was performed according to established protocols.

RESULTS

Hematoxylin–Eosin Findings

Control Group (Figure 1): Placental sections from the control group demonstrated well-preserved chorionic villi with regular contours and uniform size. The syncytiotrophoblast layer was continuous and morphologically intact. The villous stroma appeared compact, with no evidence of degeneration, edema, or excessive fibrin deposition. Vascular structures were patent and evenly distributed, and intervillous spaces were well defined. Syncytial knot formation was minimal and within physiological limits.

 

 

Figure 1: Placental histology of the control group. Arrow: chorionic villus; arrowhead: syncytial knot; st: stroma; asterisk: villous capillary; f: fibrin deposition; star: intervillous space. Scale bar: 50 µm; Magnification: ×20.

 

High BMI Group (Figure 2): Placentae obtained from women with excessive gestational weight gain exhibited pronounced histopathological alterations. Chorionic villi appeared irregular, enlarged, and structurally disorganized. Stromal degeneration, including vacuolization and loss of normal connective tissue architecture, was frequently observed. Marked vascular congestion with erythrocyte accumulation was evident within villous capillaries and intervillous spaces. Fibrin deposition was increased in both villous and intervillous regions. Additionally, syncytial knots were more numerous and prominent compared with the control group.

 

 

Figure 2: Placental histopathological alterations in the high-BMI group. Arrow: chorionic villus; arrowhead: syncytial knot; st: stroma; asterisk: villous capillary; f: fibrin deposition; star: intervillous space. Scale bar: 50 µm; Magnification: ×20.

 

DISCUSSION

The present study demonstrates that excessive weight gain during pregnancy is associated with distinct placental histopathological alterations identifiable using routine Hematoxylin–Eosin staining. Compared with normal-weight pregnancies, placentae from women with high BMI exhibited significant villous structural disruption, stromal degeneration, vascular congestion, increased fibrin deposition, and enhanced syncytial knot formation. These findings are consistent with previous reports indicating that maternal metabolic stress adversely affects placental development^9-12. Villous disorganization and stromal degeneration may reduce the effective surface area available for maternal–fetal exchange, while vascular congestion suggests impaired uteroplacental blood flow ¹³. Increased fibrin deposition is commonly interpreted as a marker of placental injury and hypoxic stress and has been associated with reduced placental efficiency ¹⁴.

The observed increase in syncytial knots may reflect accelerated trophoblastic turnover or chronic placental stress ¹⁵. Although syncytial knot formation can be a physiological feature of term placentae, excessive accumulation is often associated with placental hypoxia and impaired perfusion ^16,17. Taken together, these histopathological changes suggest that excessive gestational weight gain creates a suboptimal intrauterine environment by compromising placental structure ¹⁸. Such alterations may contribute to adverse fetal outcomes and support the concept that maternal metabolic status plays a critical role in shaping placental morphology.

In conclusion, routine H&E staining provides valuable insight into placental structural changes associated with excessive maternal weight gain. Recognition of these alterations may enhance understanding of placental dysfunction in high-risk pregnancies and underscores the importance of optimal weight management during gestation.

CONCLUSION

Excessive gestational weight gain is associated with distinct histopathological alterations in the placenta. Routine Hematoxylin–Eosin examination revealed disruption of chorionic villous architecture, stromal degeneration, increased fibrin deposition, vascular congestion, and enhanced syncytial knot formation in placentae from the high-BMI group compared with controls. These structural changes suggest compromised placental integrity and may reflect an adverse intrauterine environment, underscoring the importance of appropriate maternal weight management during pregnancy.

Acknowledgements: This study was part of doctoral thesis of Dr. Özkan Yükselmiş at department of Histology and Embryology, Dicle University. 

Ethical Approval: This study was approved by the Dicle University Faculty of Medicine Non-Interventional Clinical Research Ethics Committee (Approval date: 16 April 2025; Approval number: 2025/150). All procedures were conducted in accordance with the ethical standards of the institutional and national research committees and with the principles of the Declaration of Helsinki.

Informed Consent: Informed consent was obtained from all participants prior to inclusion in the study.

Conflict of Interest: The author declares that there is no conflict of interest regarding the publication of this thesis.

Funding: This research was funded by Dicle University Scientific Research Platform (DÜBAP) by project number: TIP.25.029.

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