Medical biomonitoring of maternal and fetal exposure to carbon monoxide and its modification by demographic and obstetric characteristics

Abstract

Background: There is a paucity of organized human biomonitoring, including that of carbon monoxide (CO) in the Niger
Delta, Nigeria. The study aims to quantify the impact of maternal exposure to CO in the first trimester of pregnancy and its
modification by maternal demographic and obstetric factors.
Methodology: It was of cross-sectional design conducted at the Rivers State University Teaching Hospital (RSUTH) in
Nigeria. Four hundred and ninety consecutive pregnant women in the first trimester were recruited from the antenatal clinic
from January 2021 to January 2022. Demographic, social, and obstetric characteristics were recorded. Maternal exhaled CO
concentration (ECOC) and maternal and fetal carboxyhaemoglobin concentrations (MCOHC and FCOHC) were measured
with the aid of a smokelyzer. Data were analyzed, using SPSS version 25.0 software. Ethical approval was obtained from the
RSUTH Ethics Committee.
Results: The mean values of ECOC, MCOHC, and FCOHC were 3.25±2.51 ppm, 1.15±0.40%, and 0.93±0.72% respectively
and the severity (mild, moderate, and severe) of the impact was inversely proportional to the number of women affected. There
were statistically significant differences in the mean values of ECOC, MCOHC, and FCOHC in the following maternal
characteristics: age, educational levels, BMI, gravidity, and parity. In the case of FCOHC, the measures of the differences
were as follows: p:<0.019, <0.020, <0.0001, <0.0001, and <0.038 for age categories, educational levels, BMI, gravidity, and
parity respectively. There were statistically significant positive correlations between the BMI and the mean values of ECOC,
MCOHC, and FCOHC.
Conclusion: The higher the severity of exposure to CO (mild, moderate, and severe), the lower the number of impacted
pregnant women. There were statistically significant differences in the mean values of ECOC, MCOHC, and FCOHC in
women of different ages, educational levels, BMI, gravidity, and parity categories.