Carboxyhemoglobin levels in umbilical cord blood of women with pre-eclampsia and intrauterine growth restriction

Abstract

Pre-eclampsia (PE) and intrauterine growth restriction (IUGR) are associated with abnormal placentation. Heme oxygenase (HO) and carbon monoxide (CO) are involved in normal placental development and function and vasomotor control in the placenta. The objective of our study was to measure CO levels, as assessed by carboxyhemoglobin (COHb) levels in the umbilical cord arterial blood of women with PE, normotensive IUGR (<10th percentile for birth weight), and normotensive pregnancies with appropriate-for-gestational age (AGA) infants. We prospectively analyzed COHb levels in the umbilical arterial blood of women with PE, normotensive IUGR, and normotensive AGA pregnancies. Exclusion criteria included cigarette smoke exposure, hemolytic disorders, a positive direct anti-globulin test, chronic hypertension, fever, and any significant medical illness. COHb levels were measured using the ABL 725 blood gas analyzer. There were 41 women in the normotensive AGA group, 42 in the PE group, and 36 in the normotensive IUGR group. Maternal age, mode of delivery, gravidity, parity, and gender of the infants were similar in the three groups. Gestational age and birth weight were significantly higher in the normotensive AGA group compared with the other two groups. COHb levels were significantly lower in the PE group compared with the normotensive AGA group (0.38±0.06% vs. 0.77±0.11%, P<0.05). COHb levels, although lower in the normotensive IUGR group compared with the normotensive AGA group, did not reach statistical significance. Our data suggests the HO-CO system may have a role in the pathogenesis of PE. We also, for the first time, provide information on umbilical arterial COHb levels in normotensive IUGR pregnancies.