Micronutrient deficiencies represent a critical global public health challenge, particularly among pregnant women in low- and middle-income countries. Iron deficiency anemia affects approximately 37% of pregnant worldwide reflecting substantial gaps in hemoglobin synthesis and oxygen transport capacity ( 1 ). In some regions, multiple micronutrient deficiency and anemia prevalence among expectant mothers exceed 50%, with concurrent deficits in zinc and selenium observed across trimesters ( 2 ), exacerbating risks for adverse outcomes. These deficits have been consistently linked to maternal morbidity, including anemia and hemorrhage, and to negative fetal endpoints such as preterm birth, low birth weight, and impaired neurodevelopment ( 3 ).

Iron mineral is indispensable for fetal neurodevelopment: it underpins neurotransmitter synthesis, myelination, cellular differentiation in the developing brain and early-life iron underloading has been shown to produce long-term neurobehavioral deficits ( 4 ). Zinc functions in cell proliferation, DNA replication and immune competence. Maternal zinc deficiency is associated with fetal growth restriction, congenital anomalies, and a small but significant increase in preterm birth risk ( 5 ). Selenium, as a cofactor for glutathione per-oxidases and other selenoproteins, is vital for antioxidant defense in both mother and fetus; low maternal selenium may depict oxidative stress as can be found in preeclampsia ( 6 ). Cortisol, the primary glucocorticoid secreted by the maternal adrenal cortex, increases throughout pregnancy due to elevated corticosteroid-binding globulin levels and heightened hypothalamic pituitary axis (HPA) activity. Hypertensive disorders remain a leading cause of maternal and perinatal mortality. Hypertensive disorders of pregnancy constitute a leading cause of maternal and perinatal mortality worldwide ( 7 ).

In Nigeria, few studies have concurrently evaluated the full spectrum of micronutrient status, cortisol levels, and blood pressure in pregnant women. Understanding the interplay between micronutrient status, maternal cortisol, and blood pressure is essential for tailoring interventions to optimize both maternal and fetal health outcomes in this region. Therefore, this study aims to assess and compare serum iron, zinc, and selenium concentrations, cortisol levels, and blood pressure measurements in pregnant and non-pregnant women, and to examine variations in these parameters among pregnant women by maternal age group, trimester of gestation, and adherence to routine antenatal medication.

Ethical approval was obtained from the Research Ethics Committee of the School of Medical Laboratory Technicians, Iyi-Enu Mission Hospital, Ogidi, Anambra State, and all participants provided written informed consent prior to enrollment. All procedures were according to 1975 Helsinki Declaration.

In Table 1, the pregnant group demonstrated significantly lower levels of iron, zinc, and selenium compared to the non-pregnant group (p=0.0001). Additionally, cortisol levels were higher in the pregnant group compared to the non-pregnant group (p=0.0001). Additionally, the systolic and diastolic blood pressure values were lower in the pregnant women compared to their non-pregnant counterparts (p=0.0002). In Table 2, no significant differences (p>0.05) were observed in micronutrients, cortisol, and blood pressure across the age brackets (18–26 years, 22–35 years, and 36–43 years).

The comparison across pregnancy trimesters also yielded no significant differences (p>0.05), as shown in Table-3. Among the pregnant women, cortisol was higher in those who reported always adhering to their routine medications compared to those who did not always take their routine drugs (p=0.0474). However, other parameters, including iron, zinc, selenium levels, and blood pressure, showed no differences based on medication adherence (p>0.05).

The study examined the levels of selenium, zinc, iron, cortisol and blood pressure in pregnant women attending a healthcare facility in Anambra State. From the findings, selenium, zinc, and iron levels were lower in pregnant women compared to non-pregnant women, emphasizing the role of dietary intake and supplementation in mitigating deficiencies. Selenium and zinc are critical for antioxidant defense and immune function, which are vital during pregnancy. The observed lower levels may be attributed to the physiological demands of these micronutrients during pregnancy, characterized by increased requirements for micronutrients to support fetal development, maternal tissue growth, and placental function. Alongside selenium, sufficient zinc intake plays a critical role in supporting successful embryo-genesis and lowering the likelihood of preterm birth ( 10 ). These results align with those of Iqbal et al . ( 3 ) and Ilechukwu et al . ( 6 ), who also reported lower selenium and zinc in pregnant women. Joseph et al., similarly, observed lower zinc levels but higher selenium levels in women at the late stage of pregnancy ( 11 ), while Karita et al . did not observe any differences in the plasma selenium levels of pregnant and non-pregnant Japanese women ( 12 ).

During pregnancy, the increased iron requires often exceed what can be obtained from dietary alone, making expectant mothers more susceptible to iron deficiency anaemia. Iron deficiency is common due to expanded blood volume and increased iron utilization for erythropoiesis and fetal needs. This explains the lower iron levels observed in pregnant women in the present study, which corroborates the study done by Aloy-Amadi et al. on pregnant women in Nnewi, Anambra State ( 13 ). Lower levels of hemoglobin, an iron-rich protein found in red blood cells have also been reported in pregnant women ( 14 ). However, Ezeugwunne et al . in their study did not observe any differences in the mean hemoglobin of pregnant women compared to the non-pregnant in Nnewi, Anambra State ( 15 ). The differences in the reported results may be due to nutritional status, environmental factors or population characteristics. Findings underscore importance of adequate micronutrient intake during pregnancy to prevent complications such as oxidative stress, anemia, and impaired fetal growth.

The higher cortisol levels in pregnant women can be attributed to the physiological stress of pregnancy and the activation of the HPA axis. Cortisol plays a vital role in fetal development, particularly in lung maturation and, regulation of metabolism. However, excessive cortisol may have adverse effects, including increased risk of gestational diabetes and hypertension. The finding is consistent with that of Vrijkotte et al., who also observed higher cortisol levels in pregnant women from 5 to 20 weeks of gestation ( 16 ).

The lower systolic and diastolic blood pressure observed in pregnant women compared to non-pregnant women may reflect the hemo-dynamic changes during pregnancy. Zhang et al. observed a decrease in blood pressure during early pregnancy, followed by a gradual increase in the mid and late stages of pregnancy ( 17 ). The decrease is usually associated with vasodilation and decreased peripheral vascular resistance ( 18 ). These changes are considered adaptive mechanisms to meet the circulatory demands of pregnancy. However, deviations from the normal pattern can have significant implications for maternal and fetal health. Ezeugwunne et al., however, observed higher systolic and diastolic pressures in pregnant women compared to the control group ( 15 ). There was a remarkable consistency in micronutrients, cortisol, and blood pressure levels among pregnant women across different maternal ages, trimesters, and medication adherence categories, with a notable exception in cortisol level, which was significantly higher in pregnant women who took their routine drugs regularly. This consistency can be attributed to body homeostatic mechanisms, which regulate these parameters to meet the physiological demands of pregnancy. Regardless of age, the gradual physiological changes throughout pregnancy likely allowed for balanced adaptations, minimizing variations across trimesters. For women who occasionally skipped medications, compensatory nutrient-rich diets or baseline nutrient sufficiency could have mitigated any significant deficits. Similarly, the observed stability in pressure may reflect the effectiveness of cardiovascular adaptations during pregnancy, which maintain equilibrium despite differences in these variables. On the contrary, Ezeugwunne et al . found higher systolic and diastolic blood pressure values in 6-9 months compared to 3-5 months ( 15 ). Aloy-Amadi et al . reported that serum iron decreased with increased gestational age and decreased progressively in each trimester ( 13 ). The difference in cortisol based on medication adherence highlights the importance of consistent prenatal care. Pregnant women who adhered to their medication regimen exhibited higher cortisol levels, which may reflect better physiological adaptation to pregnancy. Non-adherence could contribute to suboptimal health outcomes, including stress-related complications. The higher cortisol in pregnant women who consistently take their routine medications compared to those who do not could reflect better physiological adaptation to pregnancy. Regular medication adherence, including prenatal supplements, may optimize nutritional status and support the HPA axis, enhancing cortisol production essential for fetal development. Moreover, consistent medication use might synchronize hormonal responses, contributing to elevated cortisol as part of the body's natural stress regulatory mechanisms. Therefore, healthy and moderate levels of glucocorticoids were related to an adequate development of cognitive and emotional brain networks during certain sensitive periods ( 19 ), since these levels are not considered harmful for the infant.

The findings of the present study underscore the need for targeted interventions to address micronutrient deficiency and optimize maternal health. The prenatal supplementation, dietary counseling, and regular monitoring of micronutrients should be integral components of antenatal care. Future research should explore long-term effects of micronutrient deficiencies on maternal and child health, as well as the efficacy of the supplementation programs in diverse populations.