Association of first trimester maternal serum ferritin, vitamin D, folic acid,vitamin B12 levels and pregnancy losses

Authors

Abstract

AimSupplementing women with vitamins in early pregnancy is reported to prevent miscarriage, as micronutrient deficiencies have been linked to an increased risk of fetal loss. The objectives of this study were to determine the effectiveness and protective features of serum ferritin, Vitamin D, folic acid, and Vitamin B12 levels on miscarriage to provide a basis for clinically targeted therapy.
MethodsThe results of 88 pregnant women between 5-14 gestational weeks and 88 healthy pregnant women at the same gestational weeks were compared. The demographic and pregnancy characteristics of all pregnant women were recorded. Ferritin, Vitamin B12, folic acid, and Vitamin D levels were measured in serum samples obtained from the patient and control groups at similar weeks.
ResultsVitamin B12, folic acid, and ferritin serum levels were significantly lower in women with miscarriage than the control group (p=0.019, p<0.001, p<0.001, retrospectively). Vitamin D levels did not show a statistical difference among both groups (p>0.05). Logistic regression analysis showed that Vitamin B12 and ferritin levels within normal limits were found to be protective factors against miscarriage (p=0.043, OR = 0.451; p=0.020, OR = 0.395); however, folic acid and Vitamin D levels were not protective factors. Ferritin levels of women with missed abortions were detected significantly lower than women with spontaneous abortion (p=0.017).
ConclusionOur results indicated that the first trimester levels of maternal vitamin B12, folic acid, and ferritin were linked to fetal loss; however, there was insufficient evidence to support a link between maternal vitamin D levels and fetal loss.

Keywords

Introduction

The first trimester of pregnancy marks a crucial period characterized by rapid fetal development and physiological changes within the maternal body. Central to this developmental journey are essential vitamins and minerals such as vitamin D, iron, folic acid, and vitamin B12, each playing pivotal roles in supporting maternal health and fetal growth. Deficiencies in these micronutrients during early pregnancy have been closely linked to an increased risk of miscarriages. Understanding the intricate interplay between these micronutrients is paramount in elucidating potential preventive strategies to safeguard maternal and fetal well-being.¹
A Cochrane meta-analysis on vitamin supplementation for preventing miscarriage suggests that there is insufficient evidence to examine the effects of different combinations of vitamins on miscarriage and miscarriage-related outcomes.² However, unfavorable pregnancy issues such as preterm birth, intrauterine growth restriction, and early miscarriages are directly related to changes in maternal nutritional status during pregnancy.³
Low serum ferritin levels are associated with severe reproductive disturbances in women with recurrent pregnancy loss.⁴ Because of fetal growth and the expansion of maternal blood volume to satisfy increased oxygen requirements, there is a higher demand for iron during pregnancy.⁵ In addition to iron, folate and vitamin B12 are essential as they play a crucial role in the biosynthesis of DNA, RNA, and proteins, which are critical for fetal development.⁶ The requirement for folate increases substantially during pregnancy. Nelen et al. reported that low serum folate levels might be responsible for recurrent pregnancy losses.⁷ Vitamin D deficiency was initially linked to bone metabolism, but it has since been associated with anemia and impaired fetal development, among other health issues.^1,8 These findings suggest that interactions between micronutrients such as iron, folic acid, vitamin D, and vitamin B12 metabolism may underlie miscarriages and spontaneous abortus. For this reason, vitamin supplementation has been recommended as a miscarriage prevention strategy based on observational studies.
A strong link between pregnancy complications and decreased antioxidant defence has been identified in certain studies, although others have not found a significant correlation.^9,10 Considering the possible role of micronutrients in the pathophysiology of fetal loss, our study aimed to measure serum ferritin, vitamin D, folic acid, and vitamin B12 levels in women with miscarriage during the first trimester, and to compare these with a healthy pregnant control group. This approach may lead to a better understanding of the association.

Materials and Methods

Consecutive patients with pregnancy who were admitted to the gynecology clinic for 3 months from 01.04.2023 to 01.07.2023 were enrolled in this prospective, cross-sectional study.
Participants
Eighty-eight pregnant women with miscarriage between 5-14 gestational weeks over 18 years of age and 88 healthy pregnant individuals who were compatible with this group in terms of age, gestational week, and parity were included. All participants, who had a singleton pregnancy, did not receive any prophylactic nutrition supplement at admission. Patients’ data were recorded in a database that included clinical and demographic characteristics, hemogram, International Normalized Ratio (INR), serum levels of vitamin B12, vitamin D, folic acid, and ferritin tests. Both groups were questioned in terms of age, smoking, alcohol consumption, consanguineous marriage, and chronic diseases.
The participants did not have any genetic or anatomic abnormalities, endocrine disorders, inflammatory diseases, or maternal-fetal blood group incompatibility. Pregnant women under the age of 18 and over the age of 40, women with autoimmune diseases and chronic diseases related to blood pressure, patients with multiple pregnancies, and women with pregnancy loss outside of 5-14 gestational weeks or with a positive fetal heartbeat were excluded.
Gestational week was calculated according to the last menstrual date. Those included in the study group were divided into two groups: spontaneous abortion and missed abortion. The spontaneous abortion group consisted of patients who presented with bleeding and were diagnosed with complete or incomplete abortion. The missed abortion group consisted of anembryonic pregnancies in which the gestational sac was larger than 25 mm and no fetal image was observed and/or patients with a fetal image larger than 7 mm and no fetal heart activity. Ultrasonographic examination was performed by the same physician for all patients.
Collection of Samples
After 8 hours of fasting, morning venous blood samples were collected into vacuum gel tubes to investigate hemogram and INR. Vitamin B12 levels were measured by chemiluminescence emission technique (reference range: 197-771 ng/L). 25(OH)D levels were measured by chemiluminescence emission technique (reference ranges: <12 µg/L deficiency, 12-20 µg/L insufficiency, >20 µg/L adequate/normal). Folic acid levels were measured by chemiluminescence emission technique (reference range: 3.89-26.8 µg/L). Ferritin levels were measured by chemiluminescence emission technique (reference range: 13-150 µg/L).
Ethical Approval
This study was approved by the Ethics Committee of the University of Health Sciences, Şişli Hamidiye Etfal Training and Research Hospital (Date: 21.02.2023, Decision No: 2243) and was performed in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants.
Statistical Analysis
For statistical analysis, SPSS 15.0 for Windows was utilized. Descriptive statistics were given as numbers and percentages for categorical variables, and mean, standard deviation, minimum, maximum, and median for numerical variables. In two independent groups, numerical variables were analyzed by Mann-Whitney U Test. Proportions in the groups were compared with the Chi-Square test. Protective effects were analyzed by Logistic Regression Analysis. Statistical alpha significance level was accepted as p<0.05.

Results

The ages of the participants ranged between 18 and 40 years. The mean age of women with miscarriage was 31.9 ± 6.4 years, and the mean age of healthy pregnant women was 31.5 ± 5.7 years (p>0.05). The mean gravida, parity, and miscarriage frequencies of the study group were significantly higher in the women with miscarriage group; however, the mean gestational week according to the last menstrual period was significantly lower (p=0.005, p=0.017, p=0.014, p<0.001, respectively). The two groups did not differ significantly in terms of smoking, consanguineous marriage, or Rh incompatibility (p>0.05). None of the participants had alcohol use or chronic diseases. Table 1 illustrates the demographic and clinical characteristics of patients.
Vitamin B12, folic acid, and ferritin serum levels were found to be significantly lower in the women with miscarriage group than in the control group (p=0.019, p<0.001, p<0.001, respectively). Hemoglobin, folic acid, and INR levels were not significantly different between both groups (p>0.05). However, 25(OH) vitamin D level, 25(OH) vitamin D <12 µg/L deficiency ratio, 25(OH) vitamin D 12-20 µg/L insufficiency ratio, and 25(OH) vitamin D >20 µg/L adequate/normal ratio did not show a statistically significant difference between the groups (Table 2).
Logistic regression analysis showed that vitamin B12 and ferritin levels within normal limits were protective factors (p=0.043, OR = 0.451; p=0.020, OR = 0.395). However, folic acid and 25(OH) vitamin D levels were not found to be protective factors (p>0.05) (Table 3).
The women with miscarriage group was divided into two subgroups: (1) patients with missed abortion, (2) patients with spontaneous abortion. We did not find any statistically meaningful differences in terms of age, gravida, parity, history of abortion, gestational week according to last menstrual period, smoking, consanguineous marriage, and Rh incompatibility between the subgroups (p>0.05). Vitamin B12, folic acid, and vitamin D levels were not significantly different; however, ferritin levels of women with missed abortion were significantly lower than those of women with spontaneous abortion (p=0.017).

Discussion

The purpose of this study was to assess serum ferritin, vitamin D, folic acid, and vitamin B12 levels in women with miscarriage during the first trimester, and to compare them with women who had healthy pregnancies. Moreover, we evaluated the levels of these micronutrients and ferritin to detect their association between spontaneous abortion and missed abortion. In this study, which examined women with miscarriage and healthy pregnant women with similar demographic and clinical characteristics, serum vitamin B12, folic acid, and ferritin levels were found to be significantly lower in women with miscarriage than in healthy controls. Advanced statistical analyses showed that ferritin may be a protective factor for pregnancy loss. Additionally, blood analysis of patients with missed abortion and spontaneous abortion showed that ferritin was significantly lower in the missed abortion subgroup.
Folate is essential for the developing fetus, as it is directly involved in the biosynthesis of DNA, RNA, and proteins. In addition to folate deficiency, defective folate metabolism, such as hyperhomocysteinemia and vitamin B12 deficiency, is known to increase the risk of neural tube defects, congenital abnormalities, placental abruption, and heart defects.^1,11 Our results showed that serum vitamin B12 and folic acid levels of pregnant women diagnosed with miscarriage were significantly lower than in healthy controls, and linear regression analyses conducted in this study found that vitamin B12 acts as a protective factor against miscarriages. In a study from our country, it was reported that iron and vitamin B12 deficiencies were relatively common in the pregnant population.¹² Research to date has shown a relationship between maternal serum folic acid and vitamin B12 status and the presence of miscarriage.^11,13 Zhang et al. reported that folic acid supplements were identified as protective factors for the prevention of missed abortions.¹⁴ A recently published Cochrane review suggests the use of folic acid supplements for pregnant women in low- and middle-income countries.¹¹ Our results support that vitamin B12 supplementation in addition to folate could be considered for fetal well-being, especially where dietary patterns are generally based on vegetables.
Although traditionally associated with maternal and neonatal bone disease, vitamin D deficiency is more common in women who develop major reproductive and obstetric complications such as pre-eclampsia, gestational diabetes, and preterm delivery.¹ The prevalence of hypovitaminosis D among pregnant women in their first trimester was reported to be up to 70%.¹⁵ The placenta is a key tissue for vitamin D accumulation, having important effects on trophoblast invasion and remodeling of placental arteries. These processes are impaired in cases of abortion.^16,17 Vitamin D prevents the occurrence of antiphospholipid syndrome by reducing the expression levels of anti-β2 glycoprotein and tissue factor in cases of recurrent pregnancy loss.¹⁸ There is also an inverse relationship between vitamin D and thyroid peroxidase antibody levels in patients with recurrent pregnancy loss and autoimmune thyroid disease.¹⁹ Hou et al. investigated low 25(OH)D vitamin levels in early pregnancy losses.²⁰ Their study of 120 women showed an association between pregnancy loss and low vitamin D levels. The fact that this study was conducted in China with a different population and average age may have led to different results from ours. Our findings revealed that both women with miscarriage and healthy pregnant groups had low serum vitamin D levels; however, there was no significant difference in mean serum vitamin D levels between the groups. It has been reported that vitamin D deficiency is common in pregnant women and their neonates even in springtime in Türkiye, generally due to lifestyle and dietary patterns of mothers.²¹ Ji et al. compared 215 women with recurrent pregnancy loss with 77 women with one or more healthy deliveries. Vitamin D levels were found to be lower in the group with recurrent pregnancy loss.²² In this study conducted in China, although the control group remained below the insufficiency limit, the lower level in the group with recurrent pregnancy losses made the result significant. Differences in research methods and populations may explain the discrepancy, as the control group in our study also had insufficiency and deficiency of vitamin D.
Anemia has been associated with many complications, including maternal mortality, stillbirth, preterm birth, low birth weight, small-for-gestational-age birth, and other pregnancy complications.¹ Ferritin is a protein that stores iron, and serum ferritin concentration reflects body iron stores. It is also an acute-phase reactant, with iron-independent synthesis increased by inflammatory cytokines and oxidative stress. Iron is essential for placental and fetal development. Severe iron deficiency can lead to adverse pregnancy outcomes such as increased risk of preterm delivery and fetal loss. In addition to placental and fetal growth, iron is required for the expansion of the maternal red blood cell compartment.²³ Georgsen et al. reported that serum ferritin levels are related to pregnancy losses in women with recurrent pregnancy loss.⁹ Their results showed that women with repetitive fetal loss had lower serum ferritin compared with women without fertility problems, and they reported an inverse association between serum ferritin levels and pregnancy losses, supporting our results. Furthermore, we found that ferritin was important as it was a protective factor against miscarriage. Xu et al. investigated the relationship between pre-pregnancy hemoglobin concentration and the risk of spontaneous abortion in a cohort study conducted on more than 3.9 million women in rural China.²⁴ Severe anemia and low hemoglobin concentrations before pregnancy were associated with an increased risk of spontaneous abortion. The sample size of this study is a strength; however, serum values obtained 6 months before pregnancy were used, and the use of iron supplements was not noted, which is a limitation. In our study, we excluded individuals taking iron supplements, potentially yielding more realistic results as we observed both hemoglobin and ferritin values during pregnancy. While our study revealed no significant difference in serum hemoglobin values, there was a significant difference in serum ferritin values. It is a known fact that women with repetitive fetal loss have a greater prevalence of iron deficiency.²⁵ Our results encourage the evaluation of maternal serum hemoglobin, ferritin, and iron levels in the first trimester of pregnancies.

Limitations

Our study has a few limitations. First, it is a hospital based, tertiary clinic study. Second, these women were not followed during pregnancy and further micronutritional status could not be evaluated. The strength of the present study lies in its inclusion of a relatively high number of participants who were not under supplement intake and shared a similar demographic and clinical background. In addition, this study pointed out that there are several problems which need to be clarified and evaluated in further studies regarding micronutritional supplementation during pregnancy in our country.

Conclusion

These results indicated that maternal Vitamin B12, folic acid and ferritin levels in the first trimester were associated with fetal loss; however, we found limited evidence for the association of maternal Vitamin D levels in contrary to up-to-date research data. This suggested that sufficient maternal Vitamin B12, folic acid, and iron level was an important factor in improving fetal growth and development. The possibility of interaction among vitamin D levels during pregnancy warrants further research to explore the risk of adverse pregnancy outcomes.

Declarations

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About This Article

Received:

February 23, 2024

Accepted:

April 19, 2024

Published Online:

May 5, 2024

Printed:

July 1, 2024