http://informahealthcare.com/jmf ISSN: 1476-7058 (print), 1476-4954 (electronic) J Matern Fetal Neonatal Med, 2015; 28(6): 709–712 ! 2014 Informa UK Ltd. DOI: 10.3109/14767058.2014.929110
ORIGINAL ARTICLE
Maternal plasma homocysteine levels in intrauterine growth retardation Ali Yeter, Hasan Onur Topcu, Ali Irfan Guzel, Emre Ozgu, and Nuri Danisman Division of Gynecology, Dr Zekai Tahir Burak Women’s Health Education and Research Hospital, Ankara, Turkey
Abstract
Keywords
Objective: To investigate a possible correlation between maternal plasma homocysteine (HC) concentrations and intrauterine growth retardation (IUGR). Methods: The patients were divided into the IUGR group and controls. The IUGR group consisted of 40 women and their newborns with birth weight 5the 10th percentile for gestational age, whereas 45 infants with birth weight the 10th percentile comprised the control group. Blood samples were obtained from the antecubital vein within 24 h after the delivery. Results: No significant differences between the population characteristics in the two groups were found. There was a statistically significant difference in serum concentrations of HC: 5.6 ± 1.9 mmol/L in the IUGR group and 4.6 ± 1.2 mmol/L in controls (p ¼ 0.01). ROC curve analysis demonstrated that pulsatility index (PI), resistance index (RI) and HC concentrations were discriminative markers in IUGR group. According to Pearson correlation analysis there was a possible association between HC concentrations and PI, RI and middle cerebral artery Doppler velocimetry (MCA). Conclusion: Higher maternal HC concentration and lower birth weight were observed in the IUGR group as compared to the control group. We are of the opinion that maternal plasma homocysteine concentration may be a prognostic marker in intrauterine growth retardation.
Birth weight, homocysteine, intrauterine growth retardation
Introduction IUGR is defined as a failure of the fetus to gain weight appropriate for its gestational age and sex, as determined by population standards. Most common cut-off points are below the 10th percentile [1]. Causes for IUGR remain unknown, although several determinants have been identified. The association of inherited and acquired thrombophilia with the risk of eclampsia, abruptio placentae, IUGR, and stillbirth has been the subject of much research in recent years [2]. Homocysteine is a sulfhydryl amino acid derived from the metabolic conversion of methionine, which is dependent on several vitamins (folic acid, vitamin B12, riboflavin, and vitamin B6) as cofactors or cosubstrates [3]. In a casecontrolled, cross-sectional, and prospective study, Cattaneo et al. [3], showed that hyperhomocysteinemia is associated with an elevated risk of arterial and venous thrombosis, independently of other established risk factors. Burke et al. [4], measured maternal total HC immediately after birth and compared it between 37 IUGR cases and 35 controls, but found no statistically significant difference. In another large study, the probability of a mother giving birth to a baby with growth retardation was proven to
Address for correspondence: Ali Irfan Guzel, Division of Gynecology, Dr Zekai Tahir Burak Women’s Health Education and Research Hospital, Ankara, Turkey. E-mail: [email protected]
History Received 22 November 2013 Revised 25 May 2014 Accepted 26 May 2014 Published online 26 June 2014
decrease with increasing HC, in other words birth weight increased parallel to HC concentration [5]. We believe that higher plasma homocysteine concentration may result in reduced birth weight and poor perinatal outcomes. Thus, our study was designed to investigate the possible correlation between maternal HC plasma concentration and IUGR.
Materials and methods The study was conducted at Dr. Zekai Tahir Burak Women’s Health Care Education and Research Hospital, Ankara, Turkey. The participants who gave birth between May 2009 and September 2009 were recruited. Gestational age (weeks) was assessed by an ultrasound examination (GE Logiq 200 PRO Ultrasound Device, Fairfield, CT) and/or according to the last menstrual period. Doppler velocimetry measurements of the pulsatility index (PI) and the resistance index (RI) of the umbilical artery, and middle cerebral artery (MCA) were performed by the same clinician with color Doppler sonography with a 7.5 MHz pulse endovaginal Doppler system for blood flow analysis (Aloka Co., Tokyo, Japan). The women were divided into two groups: the IUGR group and the control group. Forty newborns with birth weight below the 10th percentile for gestational age formed the IUGR group and 45 infants with birth weight at or above the 10th percentile comprised the control group [6].
710
A. Yeter et al.
J Matern Fetal Neonatal Med, 2015; 28(6): 709–712
The exclusion criteria were: multiple pregnancy, structural or chromosomal anomalies, smoking and no regular follow-up visits, and no multivitamin supplementation. The study was approved by the Ethical Committee and Institutional Review Board of Dr. Zekai Tahir Burak Women’s Health Care Education and Research Hospital. Written informed consent was obtained from each participant. Blood samples were collected from the antecubital vein within 24 h after delivery and kept in ethylenediaminetetraacetic acid (EDTA) blood tubes. The samples were centrifuged for 10 minutes at 3000 revolutions per minute, then stored at 70 C. Plasma HC concentrations were measured by using an Immulite 2000 Homocysteine Immunoassay kit (Siemens Medical Solutions Diagnostics, Malvern, PA).
Statistics Statistical analysis was performed using SPSS version 19.0 (SPSS, Chicago, IL). Due to abnormal distribution of all variables (Shapiro-Wilk test), Mann–Whitney-U test was used to determine the differences between the two groups. The receiver operator characteristic (ROC) curve analysis was used to establish the cutoff values for pulsatility index (PI) and resistance index (RI) of umbilical artery Doppler velocimetry, middle cerebral artery (MCA) Doppler velocimetry, maternal HC concentrations and APGAR scores. Correlation analysis between maternal serum HC concentrations and PI, RI, MCA velocimetry and pregnancy weight gain was performed using Pearson correlation analysis.
Results Demographic and fetal parameters are presented in Table 1, as well as the distribution of maternal characteristics for the IUGR group and the control group. There was no statistical difference between the groups of women in terms of age, gravidity, parity, gestational age, maternal weight gain and antenatal folic acid supplementation. The birth weight was 2206.50 ± 593.66 g in the IUGR group and 3319.33 ± 355.24 g in the control group. The difference in birth weight between the groups was statistically significant (p50.01; Table 1). Doppler velocimetry of the umbilical and middle cerebral artery values were statistically significantly different between
the groups (p50.05). PI and RI of umbilical artery Doppler velocimetry values were higher and MCA Doppler velocimetry values were lower in the IUGR group. The medians of APGAR scores were 6.80 (3–7) in the IUGR group and 7.09 (7–8) in controls. No statistically significant difference in terms of APGAR scores (p ¼ 0.740) was noted between the groups (Table 1). Maternal HC concentrations showed statistically significant difference (p50.001) between the groups (HC: 5.6 ± 1.9 mmol/L in the IUGR group and 4.6 ± 1.2 mmol/L in the control group). ROC areas under the curves (AUC) of PI, RI, MCA, maternal serum HC concentrations and APGAR scores were with AUC (95% CI) as follows: 0.683 (0.567– 0.800), 0.711 (0.595–0.827), 0.322 (0.208–0.436), 0.635 (0.513–0.757) and 0.397 (0.276–0.518), respectively. The cut off values and sensitivity and specificity for PI, RI and HC concentrations were as follows: 0.625 (94.4–95.5), 0.465 (91.7–93.2) and 2.485 (97.2–97.7); respectively (Figure 1 and Table 2). The correlation between maternal serum HC concentration and PI, RI, MCA velocimetry and pregnancy weight gain is shown in Table 3. A statistically significant correlation between MCA velocimetry, pregnancy weight gain and HC was not found. However, there was a statistically significant correlation between PI, RI and HC.
Discussion Our study investigated maternal serum HC concentration and analyzed the prognostic role of this marker in IUGR. Demographic characteristics were similar between the groups. Umbilical artery PI, RI and MCA Doppler velocimetry values, APGAR scores and maternal serum HC concentrations were statistically significantly different between the groups. We also performed ROC analysis in order to determine which of the parameters may be discriminative in the IUGR group and found the AUC (95% CI) for PI, RI and maternal serum HC concentrations to be: 0.683 (0.567–0.800), 0.711 (0.595– 0.827), 0.635 (0.513–0.757), respectively. According to our results, these three parameters may be the discriminative factors between IUGR and normal fetuses. IUGR is defined as the failure of the fetus to achieve its full growth potential. The pathogenesis of IUGR focuses on
Table 1. Comparison of demographic variables and homocysteine concentrations between IUGR and control groups. Variables Age (Year) *Gravidity 3 *Parity 1 Pregnancy weight gain (kg) PI RI MCA velocimetry Antenatal folic acid supplementation (n(%)) *APGAR 1 HC (mmol/L) Gestational age (weeks) Birth weights (g)
IUGR group (n ¼ 40)
Control group (n ¼ 45)
24.7 ± 4.9 33 (73.3) 35 (77.7) 11.8 ± 4.3 0.99 (0.58–2.57) .62 (0–1) 4.49 (2.53–8.00) 32 (80.0) 6.77 (3–8) 5.6 ± 1.9 35.17 ± 3.59 2206.50 ± 593.66
24.6 ± 4.6 32 (80.0) 36 (90.0) 12.3 ± 3.8 0.83 (0.21–1.42) 0.55 (0–1) 5.57 (2.95–8.63) 34 (75.55) 7.09 (7–8) 4.6 ± 1.2 36.33 ± 2.06 3319.33 ± 355.24
p 0.915 0.507 0.393 0.627 0.004 0.001 0.004 0.675 0.740 0.009 0.069 50.01
PI: pulsatility index; RI: resistance index; MCA: middle cerebral artery; HC: maternal serum homocysteine concentrations; APGAR 1; 1th minute apgar scores; data was presented as n(%). Bold p values are statistically significant. *Data presented as median.
Homocysteine levels in IUGR
DOI: 10.3109/14767058.2014.929110
711
Table 2. Area under curve (AUC), cut off values and sensitivity and specificity of the statistically significant variables calculated by ROC analysis. 95% CI
Umbilical artery PI Umbilical artery RI MCA velocimetry HC APGAR scores
AUC
Lower
Upper
Cut off value
Sensitivity (%)–Specificity(%)
0.683 0.711 0.322 0.635 0.397
0.567 0.595 0.208 0.513 0.276
0.800 0.827 0.436 0.757 0.518
0.625 0.465 NS 2.485 NS
94.4–95.5 91.7–93.2 NS 97.2–97.7 NS
PI: pulsatility index; RI: resistance index; MCA: middle cerebral artery; HC: maternal serum homocysteine concentrations, NS: not significant.
Table 3. Correlation between maternal serum homocysteine concentration and PI, RI, MCA velocimetry and pregnancy weight gain by using Spearman’s correlation analysis. PI
Maternal serum HC concentrations
RI
MCA velocimetry
Pregnancy weight gain
CC
p
CC
P
CC
p
CC
P
0.326
0.003
0.228
0.40
0.374
50.001
0.036
0.574
CC: correlation coefficient, PI: pulsatility index, RI: resistance index, MCA: middle cerebral artery, HC: homocysteine.
Figure 1. Receiver operating characteristic (ROC) areas under the curves (AUC) of PI and RI of umbilical artery and MCA Doppler velocimetry, maternal serum HC concentrations and APGAR scores.
oxidative damage, endothelial dysfunction, hyperhomocysteinemia, and utero-placental insufficiency [7]. Biri et al. [8], evaluated the role of oxidative stress in IUGR. They found a relationship between oxidative damage and IUGR in maternal blood plasma, umbilical cord blood, and placental oxidative and antioxidative parameters. Adequate utero-placental blood flow is necessary for fetal development. The feto-placental circulation control depends on vasoactive substances produced by local factors. Homocysteine is a sulfhydryl amino acid derived
from the metabolic conversion of methionine. The normal course of HC in pregnancy is as follows: 8–16 weeks of gestation: 5.6 mmol/L (3.9–7.3); 20–28 weeks of gestation: 4.3 mmol/L (3.5–5.3); and 36–42 weeks of gestation: 5.5 mmol/L (3.3–7.5) [9]. Poor pregnancy prognosis and outcome, such as early pregnancy loss, placental abruption, placental infarction, preeclampsia, and IUGR, were associated with higher plasma HC concentrations [10]. Prevalence of hyperhomocysteinemia in pregnant women with IUGR is estimated at 24% [11]. We found a statistically significant correlation between higher HC concentration and IUGR as compared with the control group. However, none of our subjects had HC concentrations higher than 15 mmol/L. Gadhok et al. [12], studied serum HC concentrations in IUGR and also reported elevated values. Our results were similar to their findings as we also observed higher HC concentrations in the IUGR group. Increased risk of obstetric complications in pregnant women with hyperhomocysteinemia may be the result of changes in blood vessels, leading to placental infarction, and vascular damage resulting in placental insufficiency. Decreased nitric oxide function, increased oxidative stress, increased vascular smooth muscle cell proliferation, and increased secretion of inflammatory cytokines have been suggested to be responsible for the effect of HC on the endothelial function [13]. A strong association between plasma HC, history of pregnancy complications, and adverse pregnancy outcomes has been reported [14], although long time interval between the pregnancy and the blood sampling used for the HC measurement constituted a serious limitation of that research. Both, smoking and plasma HC were associated with low birth weights in that study. Only non-smokers were recruited to our study. For placental abruption, excess risk was confined to women with HC concentrations of 415 mmol/L. In contrast, malformations and other investigated outcomes were related to the central distribution of HC (5–15 mmol/L),
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with no elevated risk associated with high HC concentrations. In our research, no statistically significant difference in terms of birth weight for HC values was observed. Contrary to their original expectations, Infante-Rivard et al. [5], reported an inverse association between plasma HC and the risk of IUGR. Similar results were obtained when newborn HC concentration was investigated. The finding is rather unexpected because hyperhomocysteinemia has been believed to impair placental blood flow in blood vessels. Placental amino acid transport may be adversely affected in IUGR via several distinct mechanisms. Increased maternal HC concentrations, which are common in IUGR, competitively inhibit the placental transfer of endogenous amino acids, and preferentially, hyperhomocysteinemia would interact with the System L transporter, which is the primary mechanism of delivering essential amino acids such as leucine to the fetus [15]. In a review similar to our study, a correlation between increased risk of SGA (small-for-gestational-age) infants and elevated maternal HC concentrations was statistically insignificant. This small increase in the risk will be of clinical relevance to individual newborns [16]. Our findings were consistent with the results of that study. In summary, our study showed that elevated HC is associated with low birth weight. Therefore, we are of the opinion that HC may be a promising marker to detect IUGR cases, but larger sample studies are needed to obtain more consistent findings.
Acknowledgements We thank Ms. Izabela Mrugalska for English revision of manuscript.
Declaration of interest The authors report no conflicts of interest.
References 1. Anonymous. Intrauterine growth retardation clinical management guidelines for obstetrician-gynecologists. ACOG Pract Bull 2000; 12:1–11.
J Matern Fetal Neonatal Med, 2015; 28(6): 709–712
2. Weiner Z, Beck-Fruchter R, Weiss A, et al. Thrombophilia and stillbirth:possible connection by intrauterine growth restriction. BJOG: an international journal of obstetrics and gynaecology 2004; 111:780–3. 3. Cattaneo M. Hyperhomocysteinemia, atherosclerosis and thrombosis. Thromb Haemostasis 1999;81:165–76. 4. Burke G, Robinson K, Refsum H, et al. Intrauterine growth retardation, perinatal death, and maternal homocysteine levels. New Engl J Med 1992;326:69–70. 5. Infante-Rivard C, Rivard GE, Gauthier R, Theoret Y. Unexpected relationship between plasma homocysteine and intrauterine growth restriction. Clin Chem 2003;49:1476–82. 6. Ovali F. Intrauterine growth curves for Turkish infants born between 25 and 42 weeks of gestation. J Trop Pediatr 2003; 49:381–3. 7. Sankaran S, Kyle PM. Aetiology and pathogenesis of IUGR. Best Pract Res Clin Obstet Gynaecol 2009;23:765–77. 8. Biri A, Bozkurt N, Turp A, et al. Role of oxidative stress in intrauterine growth restriction. Gynecol Obstet Invest 2007;64: 187–92. 9. Walker MC, Smith GN, Perkins SL, et al. Changes in homocysteine levels during normal pregnancy. Am J Obstet Gynecol 1999;180: 660–4. 10. Leeda M, Riyazi N, de Vries JI, et al. Effects of folic acid and vitamin B6 supplementation on women with hyperhomocysteinemia and a history of preeclampsia or fetal growth restriction. Am J Obstet Gynecol 1998;179:135–9. 11. de Vries JI, Dekker GA, Huijgens PC, et al. Hyperhomocysteinaemia and protein S deficiency in complicated pregnancies. Brit J Obstet Gynaec 1997;104:1248–54. 12. Gadhok AK, Sinha M, Khunteta R, et al. Serum homocysteine level and its association with folic acid and vitamin B12 in the third trimester of pregnancies complicated with intrauterine growth restriction. Clin Lab 2011;57:933–8. 13. Di Simone N, Maggiano N, Caliandro D, et al. Homocysteine induces trophoblast cell death with apoptotic features. Biol Reprod 2003;69:1129–34. 14. Vollset SE, Refsum H, Irgens LM, et al. Plasma total homocysteine, pregnancy complications, and adverse pregnancy outcomes: the Hordaland Homocysteine study. Am J Clin Nutr 2000;71: 962–8. 15. Tsitsiou E, Sibley CP, D’Souza SW, et al. Homocysteine transport by systems L, A and y + L across the microvillous plasma membrane of human placenta. J Physiol 2009;587:4001–13. 16. Hogeveen M, Blom HJ, den Heijer M. Maternal homocysteine and small-for-gestational-age offspring: systematic review and metaanalysis. Am J Clin Nutr 2012;95:130–6.
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ORIGINAL ARTICLE
Maternal plasma homocysteine levels in intrauterine growth retardation Ali Yeter, Hasan Onur Topcu, Ali Irfan Guzel, Emre Ozgu, and Nuri Danisman Division of Gynecology, Dr Zekai Tahir Burak Women’s Health Education and Research Hospital, Ankara, Turkey
Abstract
Keywords
Objective: To investigate a possible correlation between maternal plasma homocysteine (HC) concentrations and intrauterine growth retardation (IUGR). Methods: The patients were divided into the IUGR group and controls. The IUGR group consisted of 40 women and their newborns with birth weight 5the 10th percentile for gestational age, whereas 45 infants with birth weight the 10th percentile comprised the control group. Blood samples were obtained from the antecubital vein within 24 h after the delivery. Results: No significant differences between the population characteristics in the two groups were found. There was a statistically significant difference in serum concentrations of HC: 5.6 ± 1.9 mmol/L in the IUGR group and 4.6 ± 1.2 mmol/L in controls (p ¼ 0.01). ROC curve analysis demonstrated that pulsatility index (PI), resistance index (RI) and HC concentrations were discriminative markers in IUGR group. According to Pearson correlation analysis there was a possible association between HC concentrations and PI, RI and middle cerebral artery Doppler velocimetry (MCA). Conclusion: Higher maternal HC concentration and lower birth weight were observed in the IUGR group as compared to the control group. We are of the opinion that maternal plasma homocysteine concentration may be a prognostic marker in intrauterine growth retardation.
Birth weight, homocysteine, intrauterine growth retardation
Introduction IUGR is defined as a failure of the fetus to gain weight appropriate for its gestational age and sex, as determined by population standards. Most common cut-off points are below the 10th percentile [1]. Causes for IUGR remain unknown, although several determinants have been identified. The association of inherited and acquired thrombophilia with the risk of eclampsia, abruptio placentae, IUGR, and stillbirth has been the subject of much research in recent years [2]. Homocysteine is a sulfhydryl amino acid derived from the metabolic conversion of methionine, which is dependent on several vitamins (folic acid, vitamin B12, riboflavin, and vitamin B6) as cofactors or cosubstrates [3]. In a casecontrolled, cross-sectional, and prospective study, Cattaneo et al. [3], showed that hyperhomocysteinemia is associated with an elevated risk of arterial and venous thrombosis, independently of other established risk factors. Burke et al. [4], measured maternal total HC immediately after birth and compared it between 37 IUGR cases and 35 controls, but found no statistically significant difference. In another large study, the probability of a mother giving birth to a baby with growth retardation was proven to
Address for correspondence: Ali Irfan Guzel, Division of Gynecology, Dr Zekai Tahir Burak Women’s Health Education and Research Hospital, Ankara, Turkey. E-mail: [email protected]
History Received 22 November 2013 Revised 25 May 2014 Accepted 26 May 2014 Published online 26 June 2014
decrease with increasing HC, in other words birth weight increased parallel to HC concentration [5]. We believe that higher plasma homocysteine concentration may result in reduced birth weight and poor perinatal outcomes. Thus, our study was designed to investigate the possible correlation between maternal HC plasma concentration and IUGR.
Materials and methods The study was conducted at Dr. Zekai Tahir Burak Women’s Health Care Education and Research Hospital, Ankara, Turkey. The participants who gave birth between May 2009 and September 2009 were recruited. Gestational age (weeks) was assessed by an ultrasound examination (GE Logiq 200 PRO Ultrasound Device, Fairfield, CT) and/or according to the last menstrual period. Doppler velocimetry measurements of the pulsatility index (PI) and the resistance index (RI) of the umbilical artery, and middle cerebral artery (MCA) were performed by the same clinician with color Doppler sonography with a 7.5 MHz pulse endovaginal Doppler system for blood flow analysis (Aloka Co., Tokyo, Japan). The women were divided into two groups: the IUGR group and the control group. Forty newborns with birth weight below the 10th percentile for gestational age formed the IUGR group and 45 infants with birth weight at or above the 10th percentile comprised the control group [6].
710
A. Yeter et al.
J Matern Fetal Neonatal Med, 2015; 28(6): 709–712
The exclusion criteria were: multiple pregnancy, structural or chromosomal anomalies, smoking and no regular follow-up visits, and no multivitamin supplementation. The study was approved by the Ethical Committee and Institutional Review Board of Dr. Zekai Tahir Burak Women’s Health Care Education and Research Hospital. Written informed consent was obtained from each participant. Blood samples were collected from the antecubital vein within 24 h after delivery and kept in ethylenediaminetetraacetic acid (EDTA) blood tubes. The samples were centrifuged for 10 minutes at 3000 revolutions per minute, then stored at 70 C. Plasma HC concentrations were measured by using an Immulite 2000 Homocysteine Immunoassay kit (Siemens Medical Solutions Diagnostics, Malvern, PA).
Statistics Statistical analysis was performed using SPSS version 19.0 (SPSS, Chicago, IL). Due to abnormal distribution of all variables (Shapiro-Wilk test), Mann–Whitney-U test was used to determine the differences between the two groups. The receiver operator characteristic (ROC) curve analysis was used to establish the cutoff values for pulsatility index (PI) and resistance index (RI) of umbilical artery Doppler velocimetry, middle cerebral artery (MCA) Doppler velocimetry, maternal HC concentrations and APGAR scores. Correlation analysis between maternal serum HC concentrations and PI, RI, MCA velocimetry and pregnancy weight gain was performed using Pearson correlation analysis.
Results Demographic and fetal parameters are presented in Table 1, as well as the distribution of maternal characteristics for the IUGR group and the control group. There was no statistical difference between the groups of women in terms of age, gravidity, parity, gestational age, maternal weight gain and antenatal folic acid supplementation. The birth weight was 2206.50 ± 593.66 g in the IUGR group and 3319.33 ± 355.24 g in the control group. The difference in birth weight between the groups was statistically significant (p50.01; Table 1). Doppler velocimetry of the umbilical and middle cerebral artery values were statistically significantly different between
the groups (p50.05). PI and RI of umbilical artery Doppler velocimetry values were higher and MCA Doppler velocimetry values were lower in the IUGR group. The medians of APGAR scores were 6.80 (3–7) in the IUGR group and 7.09 (7–8) in controls. No statistically significant difference in terms of APGAR scores (p ¼ 0.740) was noted between the groups (Table 1). Maternal HC concentrations showed statistically significant difference (p50.001) between the groups (HC: 5.6 ± 1.9 mmol/L in the IUGR group and 4.6 ± 1.2 mmol/L in the control group). ROC areas under the curves (AUC) of PI, RI, MCA, maternal serum HC concentrations and APGAR scores were with AUC (95% CI) as follows: 0.683 (0.567– 0.800), 0.711 (0.595–0.827), 0.322 (0.208–0.436), 0.635 (0.513–0.757) and 0.397 (0.276–0.518), respectively. The cut off values and sensitivity and specificity for PI, RI and HC concentrations were as follows: 0.625 (94.4–95.5), 0.465 (91.7–93.2) and 2.485 (97.2–97.7); respectively (Figure 1 and Table 2). The correlation between maternal serum HC concentration and PI, RI, MCA velocimetry and pregnancy weight gain is shown in Table 3. A statistically significant correlation between MCA velocimetry, pregnancy weight gain and HC was not found. However, there was a statistically significant correlation between PI, RI and HC.
Discussion Our study investigated maternal serum HC concentration and analyzed the prognostic role of this marker in IUGR. Demographic characteristics were similar between the groups. Umbilical artery PI, RI and MCA Doppler velocimetry values, APGAR scores and maternal serum HC concentrations were statistically significantly different between the groups. We also performed ROC analysis in order to determine which of the parameters may be discriminative in the IUGR group and found the AUC (95% CI) for PI, RI and maternal serum HC concentrations to be: 0.683 (0.567–0.800), 0.711 (0.595– 0.827), 0.635 (0.513–0.757), respectively. According to our results, these three parameters may be the discriminative factors between IUGR and normal fetuses. IUGR is defined as the failure of the fetus to achieve its full growth potential. The pathogenesis of IUGR focuses on
Table 1. Comparison of demographic variables and homocysteine concentrations between IUGR and control groups. Variables Age (Year) *Gravidity 3 *Parity 1 Pregnancy weight gain (kg) PI RI MCA velocimetry Antenatal folic acid supplementation (n(%)) *APGAR 1 HC (mmol/L) Gestational age (weeks) Birth weights (g)
IUGR group (n ¼ 40)
Control group (n ¼ 45)
24.7 ± 4.9 33 (73.3) 35 (77.7) 11.8 ± 4.3 0.99 (0.58–2.57) .62 (0–1) 4.49 (2.53–8.00) 32 (80.0) 6.77 (3–8) 5.6 ± 1.9 35.17 ± 3.59 2206.50 ± 593.66
24.6 ± 4.6 32 (80.0) 36 (90.0) 12.3 ± 3.8 0.83 (0.21–1.42) 0.55 (0–1) 5.57 (2.95–8.63) 34 (75.55) 7.09 (7–8) 4.6 ± 1.2 36.33 ± 2.06 3319.33 ± 355.24
p 0.915 0.507 0.393 0.627 0.004 0.001 0.004 0.675 0.740 0.009 0.069 50.01
PI: pulsatility index; RI: resistance index; MCA: middle cerebral artery; HC: maternal serum homocysteine concentrations; APGAR 1; 1th minute apgar scores; data was presented as n(%). Bold p values are statistically significant. *Data presented as median.
Homocysteine levels in IUGR
DOI: 10.3109/14767058.2014.929110
711
Table 2. Area under curve (AUC), cut off values and sensitivity and specificity of the statistically significant variables calculated by ROC analysis. 95% CI
Umbilical artery PI Umbilical artery RI MCA velocimetry HC APGAR scores
AUC
Lower
Upper
Cut off value
Sensitivity (%)–Specificity(%)
0.683 0.711 0.322 0.635 0.397
0.567 0.595 0.208 0.513 0.276
0.800 0.827 0.436 0.757 0.518
0.625 0.465 NS 2.485 NS
94.4–95.5 91.7–93.2 NS 97.2–97.7 NS
PI: pulsatility index; RI: resistance index; MCA: middle cerebral artery; HC: maternal serum homocysteine concentrations, NS: not significant.
Table 3. Correlation between maternal serum homocysteine concentration and PI, RI, MCA velocimetry and pregnancy weight gain by using Spearman’s correlation analysis. PI
Maternal serum HC concentrations
RI
MCA velocimetry
Pregnancy weight gain
CC
p
CC
P
CC
p
CC
P
0.326
0.003
0.228
0.40
0.374
50.001
0.036
0.574
CC: correlation coefficient, PI: pulsatility index, RI: resistance index, MCA: middle cerebral artery, HC: homocysteine.
Figure 1. Receiver operating characteristic (ROC) areas under the curves (AUC) of PI and RI of umbilical artery and MCA Doppler velocimetry, maternal serum HC concentrations and APGAR scores.
oxidative damage, endothelial dysfunction, hyperhomocysteinemia, and utero-placental insufficiency [7]. Biri et al. [8], evaluated the role of oxidative stress in IUGR. They found a relationship between oxidative damage and IUGR in maternal blood plasma, umbilical cord blood, and placental oxidative and antioxidative parameters. Adequate utero-placental blood flow is necessary for fetal development. The feto-placental circulation control depends on vasoactive substances produced by local factors. Homocysteine is a sulfhydryl amino acid derived
from the metabolic conversion of methionine. The normal course of HC in pregnancy is as follows: 8–16 weeks of gestation: 5.6 mmol/L (3.9–7.3); 20–28 weeks of gestation: 4.3 mmol/L (3.5–5.3); and 36–42 weeks of gestation: 5.5 mmol/L (3.3–7.5) [9]. Poor pregnancy prognosis and outcome, such as early pregnancy loss, placental abruption, placental infarction, preeclampsia, and IUGR, were associated with higher plasma HC concentrations [10]. Prevalence of hyperhomocysteinemia in pregnant women with IUGR is estimated at 24% [11]. We found a statistically significant correlation between higher HC concentration and IUGR as compared with the control group. However, none of our subjects had HC concentrations higher than 15 mmol/L. Gadhok et al. [12], studied serum HC concentrations in IUGR and also reported elevated values. Our results were similar to their findings as we also observed higher HC concentrations in the IUGR group. Increased risk of obstetric complications in pregnant women with hyperhomocysteinemia may be the result of changes in blood vessels, leading to placental infarction, and vascular damage resulting in placental insufficiency. Decreased nitric oxide function, increased oxidative stress, increased vascular smooth muscle cell proliferation, and increased secretion of inflammatory cytokines have been suggested to be responsible for the effect of HC on the endothelial function [13]. A strong association between plasma HC, history of pregnancy complications, and adverse pregnancy outcomes has been reported [14], although long time interval between the pregnancy and the blood sampling used for the HC measurement constituted a serious limitation of that research. Both, smoking and plasma HC were associated with low birth weights in that study. Only non-smokers were recruited to our study. For placental abruption, excess risk was confined to women with HC concentrations of 415 mmol/L. In contrast, malformations and other investigated outcomes were related to the central distribution of HC (5–15 mmol/L),
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with no elevated risk associated with high HC concentrations. In our research, no statistically significant difference in terms of birth weight for HC values was observed. Contrary to their original expectations, Infante-Rivard et al. [5], reported an inverse association between plasma HC and the risk of IUGR. Similar results were obtained when newborn HC concentration was investigated. The finding is rather unexpected because hyperhomocysteinemia has been believed to impair placental blood flow in blood vessels. Placental amino acid transport may be adversely affected in IUGR via several distinct mechanisms. Increased maternal HC concentrations, which are common in IUGR, competitively inhibit the placental transfer of endogenous amino acids, and preferentially, hyperhomocysteinemia would interact with the System L transporter, which is the primary mechanism of delivering essential amino acids such as leucine to the fetus [15]. In a review similar to our study, a correlation between increased risk of SGA (small-for-gestational-age) infants and elevated maternal HC concentrations was statistically insignificant. This small increase in the risk will be of clinical relevance to individual newborns [16]. Our findings were consistent with the results of that study. In summary, our study showed that elevated HC is associated with low birth weight. Therefore, we are of the opinion that HC may be a promising marker to detect IUGR cases, but larger sample studies are needed to obtain more consistent findings.
Acknowledgements We thank Ms. Izabela Mrugalska for English revision of manuscript.
Declaration of interest The authors report no conflicts of interest.
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