• carbon monoxide;
  • carboxyhaemoglobin;
  • hypertension;
  • pre-eclampsia;
  • parity interaction;
  • Omega Study


Rudra CB, Williams MA, Schiff MA, Koenig JQ, Dills R, Yu J. A prospective study of maternal carboxyhaemoglobin and pre-eclampsia risk. Paediatric and Perinatal Epidemiology 2010; 24: 35–44.

We aimed to measure the relationship between early-pregnancy maternal carboxyhaemoglobin and subsequent pre-eclampsia risk. A nested case–control analysis was conducted using data from a western Washington State cohort study (1996–2004). We measured maternal whole blood carboxyhaemoglobin in 128 women who developed pre-eclampsia and 419 normotensive controls (mean gestational age at blood draw, 14.8 weeks). After adjustment for confounders, high (≥1%) vs. low (<0.7%) carboxyhaemoglobin odds ratios [OR] and 95% confidence intervals [CI] were 4.09 [1.30, 12.9] in multiparous women, 0.53 [0.23, 1.26] in primiparae and 1.11 [0.55, 2.25] in the overall study population (parity interaction P = 0.01). The influence of parity on the association was unexpected. The association between high carboxyhaemoglobin and pre-eclampsia risk in multiparae implicates hypoxia at the fetal-maternal interface as a pathogenic mechanism. These results also suggest that the aetiology of the disease may differ according to parity.