Placental lesions and maternal hemoglobin levels. A comparative investigation.

A high maternal hemoglobin level during pregnancy has been correlated to a low birth weight and a low placental weight, but has not been investigated in relation to placental factors. In 330 consecutive deliveries, placental lesions, birth weight and placental weight were studied in a multiple regression analysis in relation to maternal hemoglobin concentration, taking into consideration possible confounding factors such as smoking, hypertensive disorders, weight gain, primiparity, gestational age and sex. A high maternal hemoglobin concentration (greater than 130 g/l) was correlated with a low birth weight, acute infarcts and syncytial knots. Intervillous thrombosis was more common in non-smokers and multiparous women, increasing in incidence as gestational age advanced. Infarcts and microscopic perivillous fibrin were correlated with hypertension. Microscopic perivillous fibrin was slightly associated with a high hemoglobin level (greater than 130 g/l) in a bivariate analysis. These findings may indicate that a high maternal hemoglobin level impairs the uteroplacental circulation.