The effects of maternal smoking on pregnancy outcome and placental histopathology lesions

Objective To study the effects of maternal smoking on pregnancy outcome and placental histopathology findings. Materials & methods Maternal and labor characteristics and pathological reports were compared between term placentas of complicated and uncomplicated pregnancies of: heavy smokers (>10 cigarettes per day, H-smokers), moderate smokers (<10 cigarettes per day, M-smokers) and non-smokers (controls, N-smokers). Results Birth-weights were lower in the H-smokers and M-smokers as compared to the N-smokers (p < 0.001), with a higher rate of small for gestational age (SGA): 18.2%, 19.2% and 11.4%, respectively (p = 0.01). Deliveries among smokers were characterized by higher rates of abnormal fetal heart rate tracings during labor as compared to non-smokers (p = 0.01). Rates of placental maternal and fetal stromal-vascular supply lesions was similar between the groups. Conclusions Maternal smoking is associated with higher rates of SGA. Tobacco's potential influence is probably through the disruption of normal placental epigenetic patterns, not expressed in placental histopathology lesions.