Human Biomonitoring of Maternal exposure to Carbon Monoxide in the First Trimester of Pregnancy in the Core Niger Delta

Abstract

Background: In the Niger Delta area of Nigeria, human medical biomonitoring, including that of maternal Carboxyhemoglobin (MCOHb) had never been performed irrespective of devastating environmental pollution in the region. Aim: The goals of the study were to quantify the impact of maternal exposure to CO in the first trimester of pregnancy in the core Niger Delta by measuring MCOHb concentrations and to assess the effect of maternal demographic and obstetric characteristics on the impact. Material and methods: The study was of cross-sectional design carried out at the Rivers State University Teaching Hospital (RSUTH) in Nigeria. 490 consecutive pregnant women in the first trimester were recruited from the antenatal clinic from January 2021 to January 2022. Gestational age was estimated with the aid of an ultrasound scan. Demographic, social and obstetric characteristics were taken. MCOHb concentrations were measured with the aid of a smokerlyser. Data was analyzed, using SPSS version 25.0 (Armonk, NY) software. Ethical approval was obtained from the RSUTH Ethics Committee. Results: The mean value of MCOHb concentration was 1.15±0.40% Out of the 490 patients that were assessed, 461(94.08%) had mild impact from CO exposure (MCOHb= 0.78-1.5%), 18 (3.67%) – moderate impact (MCOHb = 1.75-2.23%) and 11 (2.24%) had severe impact (MCOHb = 2.39% and above). Moderate and severe impact were most prominent in women of 25-29 and 35-39 years of age respectively at which they occurred in 11 out of 145 (7.59%) and 7 out of 103 women (6.80%) respectively and the differences at various age groups were statistically significant [X2=23.119, p<0.010, 95%CI (0.038,0.046)]. The differences in the severity of maternal impact among women with different BMI classes were statistically significant [X2=56.707, p<0.001, 95%CI (0.001,0.001)] with those with class III BMI most likely to have severe impact [4(22.22%) out of 18 patients]. There was inverse relationship between parity and the severity of the impact of CO exposure but the differences at various parity groups were not statistically significant [X2=10.580, p<0.012, 95%CI (0.101,0.113)]. There was also a paradoxical finding of 3 smokers having only mild impact. Conclusion: The mean value of MCOHb was 1.15±0.40. Mild, moderate and severe impact from maternal CO exposure was established with the moderate and severe impacts more prominent at maternal ages of 25-39 years, at higher BMI and at lower parity.