The most common problem of contemporary perinatology is a high number of congenital anomalies of which conotruncal heart defects (CHD) are one of the common defects in the developmental period [
Recent studies suggested that maternal hyperhomocysteinemia is an independent risk factor for congenital heart defects, by interfering with the development of conotruncal septum of the heart [
The aim of our study was to evaluate the differences in total homocysteine (tHcy), folate, and cobalamin levels of maternal and umbilical cord blood samples in groups of children with congenital heart defects.
A prospective, case-control study was conducted in the Department of Neonatology at the Medical University of Silesia in Katowice between January 2012 and January 2015. The study was approved by the Ethics Committee of the Medical University of Silesia (nr KNW/0022/KB1/25/13).
Among 1,271 childbirths in our unit at the time of the study we enrolled 83 neonates (6.5%) with prenatally diagnosed congenital heart defects.
The control group (CG) is comprised of 59 pairs of healthy mothers residing in the unit during the study and their healthy, full-term newborns.
All mothers from the study group underwent at least two prenatal examinations in which the congenital heart defects were diagnosed. Congenital heart defects in neonates were confirmed by echocardiography performed as soon as possible after delivery.
The exclusion criteria comprised neonates with chromosomal aberrations, complex congenital malformations, newborns from multiple pregnancies, and neonates with evidence of congenital infections, as well as those that were born to mothers with clinical chorioamnionitis. We also excluded mothers who administered medications during pregnancy, which could possibly affect homocysteine and vitamin B metabolism (i.e., folate antagonists, antiepileptic drugs, oral contraceptives, barbiturates, and levodopa) within the period of six months before conception, as well as pregnant women suffering from hypertension, thromboembolic diseases, kidney, and heart defects. Neonates from the control group underwent a cranial ultrasound and an echocardiographic examination after delivery.
All included mothers and their children with prenatally diagnosed congenital heart defect were divided into two subgroups: with conotruncal heart defects (CHD,
Nonconotruncal heart defects (non-CHD) comprised children with Atrial Septum Defect, ASD (
During childbirth, 5 milliliters of maternal blood was collected from ulnar vein and 5 ml of blood from umbilical artery from the placental side.
All blood samples were collected in EDTA-containing tubes, centrifuged for 10 minutes (2500 rotations/min) and stored at −70°C until full analysis had been made. The following was assessed: folate, cobalamin, and total homocysteine concentrations. Folate and cobalamin in serum were determined with the aid of microparticle enzyme immunoassay (MEIA), using ABBOTT reagent sets in an immunochemical analyzer (AxSYM). Total homocysteine concentration in plasma was determined by an immunochemical method with the fluorescence polarization immunoassay (FPIA) using an IMx analyzer and special ABBOTT sets. All procedures were recommended by the ABBOTT company which produces testing sets used in our examination.
Results were analyzed statistically with the certified program STATISTICA 10 (StatSoft Polska Inc.). The distribution of the data was analyzed by the Shapiro-Wilk test. Results were presented as means and standard deviations or as percentiles of the total. Baseline characteristics and biomarkers of homocysteine metabolism between all study groups were compared using Kruskal-Wallis test,
The association between variables was measured by a Spearman’s rank correlation test. For all the statistical procedures
Mothers and their neonates from all investigated groups were comparable to controls with respect to demographic-perinatal characteristics, presented in Table
Demographic characteristics of investigated neonates and their mothers.
Variable | Conotruncal heart defects ( |
Nonconotruncal heart defects ( |
Controls |
|
---|---|---|---|---|
Mothers | ||||
(i) Age (years) | 26 |
29 |
31 |
0.5 |
(ii) Primigravida |
26, 60.5% | 27, 67.5% | 35, 59.3% | 0.4 |
(iii) Dietary supplementation of folic acid |
37, 86.0% | 35, 87.5% | 53, 89.8% | 0.3 |
(iv) Delivery mode: caesarean section |
26, 60.5% | 22, 55.0% | 30, 50.8% | 0.1 |
|
||||
Newborns | ||||
(i) Gender female |
20, 46.5% | 23, 57.5% | 30, 50.8% | 0.7 |
(ii) Gestational age (weeks) | 38.5 |
37 |
39.5 |
0.6 |
(iii) Birth weight (g) | 3090 |
3313 |
3230 |
0.4 |
(iv) Head circumference (cm) | 34.5 |
34.5 |
34.0 |
0.1 |
(v) Body length (cm) | 53.0 |
54.5 |
53.5 |
0.5 |
(vi) Apgar 1st min |
||||
0–3 pts | 2, 4.7% | 1, 2.3% | 0 | 0.6 |
4–7 pts | 5, 11.6% | 8, 20.0% | 8, 13.6% | |
8–10 pts | 36, 83.7% | 32, 80.0% | 51, 86.4% | |
(vii) Apgar 5th min |
||||
0–3 pts | 0 | 0 | 0 | 0.5 |
4–7 pts | 2, 4.7% | 6, 15.0% | 5, 8.5% | |
8–10 pts | 41, 95.3% | 34, 85.0% | 54, 81.5% |
Results are shown as mean and standard deviation
We have noticed that daily dietary supplementation of folic acid (0.4 mg) was taken by 86.0% (
In our study, we observed significantly higher tHcy levels in umbilical cord blood in newborns with CHD compared to their mothers. Significant differences in tHcy concentrations were observed in umbilical cord blood between CHD compared to non-CHD groups. We also noticed higher umbilical cord tHcy levels in CHD neonates compared to controls.
However, we observed no significant differences in tHcy levels in neonates with non-CHD in comparison to their mothers and to controls.
We found no relevant differences in tHcy between mothers in all investigated groups.
All results are presented on Figure
Total homocysteine (tHcy), folate, and cobalamin levels in umbilical cord blood and mothers’ venous blood samples in all investigated groups.
Variable | Conotruncal heart defects |
Nonconotruncal heart defects |
Controls |
|
---|---|---|---|---|
Umbilical cord blood | ||||
(i) tHcy level [ |
12.6 |
7.7 |
8.1 |
0.01 |
(ii) Folate level |
13.7 |
14.3 |
15.0 |
0.2 |
(iii) Cobalamin level |
300.5 |
425.1 |
325.4 |
<0.01 |
|
||||
Mothers | ||||
(i) tHcy level |
7.2 |
7.1 |
6.8 |
0.3 |
(ii) Folate level |
10.8 |
14.1 |
15.5 |
<0.01 |
(iii) Cobalamin level |
198.8 |
269.8 |
258.7 |
<0.01 |
Results are presented as mean and standard deviation
Maternal and umbilical cord blood total homocysteine concentrations in conotruncal heart defects (CHD), nonconotruncal heart defects (non-CHD), and controls (CG). Results presented as means and standard deviations as well as 95% confidence intervals and extreme values.
No differences were shown in umbilical cord folate levels in all investigated children. However, we have noticed significant decrease folate levels in CHD mothers in comparison to mothers from non-CHD and control groups, shown in Figure
Maternal and umbilical cord blood folate concentrations in conotruncal heart defects (CHD), nonconotruncal heart defects (non-CHD), and controls (CG). Results presented as means and standard deviations as well as 95% confidence intervals and extreme values.
Neonates born with CHD presented significantly higher folate concentrations in comparison to their mothers. However, there were no noticeable differences in folate levels between neonates with non-CHD and their mothers. Similarly, folates levels were comparable in control neonates compared to their mothers.
Cobalamin levels were significantly lower in umbilical cord blood in CHD group compared to others, presented on Figure
Maternal and umbilical cord blood cobalamin concentrations in conotruncal heart defects (CHD), nonconotruncal heart defects (non-CHD), and controls (CG). Results presented as means and standard deviations as well as 95% confidence intervals and extreme values.
We have noticed relevant lower cobalamin levels in mothers from CHD and non-CHD group compared to their children. However, similar results were observed in control mothers in comparison to their neonates. We observed significant differences in cobalamin levels in CHD mothers in comparison to mothers from non-CHD and control groups.
We observed correlation between tHcy and folate levels (
We also observed correlation between folate levels in all investigated mothers and umbilical cord tHcy levels (
In this study, we analyzed biomarkers of the folate-dependent homocysteine pathway metabolism in neonates with congenital heart defects and their mothers. We noticed elevated homocysteine levels in umbilical cord blood in neonates born with conotruncal heart defects in comparison to newborns with nonconotruncal heart defects. However, some studies indicate maternal elevated homocysteine level as a main risk factor for congenital heart defects in their offspring [
The etiology of conotruncal heart diseases is complex, with both environmental and genetic causes. It has been well documented that hyperhomocysteinemia, which is often accompanied by the defects of folic acid metabolism, is associated with the occurrence of congenital defects, and it seems to be an independent risk factor of conotruncal heart defects [
Based on our results, we postulated that mothers’ homocysteine levels had no direct influence on the development of conotruncal heart defects. Thus, we suggested that hyperhomocysteinemia and decreased folate levels observed in umbilical cord blood may be associated with the disturbances in homocysteine pathway metabolism in newborns with CHD. Zhao et al. found in children with CHD a gene mutation coding for an enzyme, which plays an important role in the homocysteine remethylation process [
According to Solanky et al., remethylation of Hcy to methionine using methyl donation from folate is the prevalent pathway in the human placenta, indicating a marked reliance on folate availability [
The basis for the observed abnormal metabolic profile among neonates with conotruncal heart defects and their mothers cannot be defined without further analysis of relevant genetic and environmental factors. Therefore, confirmation by future prospective multicentre cohorts is needed.
Elevated homocysteine levels in neonates with conotruncal heart defects and folate metabolism disturbances in their mothers were noticed.
The observed differences in homocysteine and cobalamin levels between neonates with congenital heart defects suggest the influence of various agents disturbing homocysteine metabolic pathways.
The authors declare that they have no conflicts of interest.