|Year : 2019 | Volume
| Issue : 1 | Page : 8-11
The effect of placenta abruption on the risk of intrauterine growth restriction: A meta-analysis
Ensiyeh Jenabi1, Salman Khazaei2, Bita Fereidooni3
1 Pediatric Developmental Disorders Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
2 Department of Epidemiology, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran
3 Midwife in Social Security Organization, Hamadan Branch, Hamadan, Iran
|Date of Web Publication||4-Jan-2019|
Midwife in Social Security Organization, Hamadan
Source of Support: None, Conflict of Interest: None
There is a contradict findings on the effect of placenta abruption on the risk of intrauterine growth restriction (IUGR). Therefore, the objective of present meta-analysis was to identify all the eligible studies to assess the effect of placenta abruption on the risk of IUGR. The major electronic databases, including PubMed, Scopus and Web of Science, were searched to identify relevant published studies. The literature search included 551 articles until January 2018 with 35,201 participants. In the end, a total of seven references were remained for this meta-analysis. Two independent authors reviewed the retrieved the studies and extracted data. I2 statistics was used to assess of heterogeneity. The random effects model was conducted to assess pooled effects size. the results of study showed that placenta abruption has a significant effect on the risk of IUGR based on odds ratio results (2.06; 95% confidence interval: 1.57, 2.55). The result reported of the measure of effect was homogeneous (I2 = 0.0%). we presented based on reports in epidemiological studies that placenta abruption is a risk factor for IUGR.
Keywords: Abruptio placenta, foetal growth retardation, meta-analysis
|How to cite this article:|
Jenabi E, Khazaei S, Fereidooni B. The effect of placenta abruption on the risk of intrauterine growth restriction: A meta-analysis. Adv Hum Biol 2019;9:8-11
|How to cite this URL:|
Jenabi E, Khazaei S, Fereidooni B. The effect of placenta abruption on the risk of intrauterine growth restriction: A meta-analysis. Adv Hum Biol [serial online] 2019 [cited 2019 Jul 23];9:8-11. Available from: http://www.aihbonline.com/text.asp?2019/9/1/8/249519
| Introduction|| |
Placenta abruption is defined as premature separation of the normally placenta after 20 weeks of gestation and before delivery. The exact aetiology of placenta abruption is still unexplained. The risk factors for placenta abruption are advanced maternal age, cigarette smoking, high parity, uterine leiomyoma, mullerian anomalies, cocaine and alcohol using. It is one of the common causes of bleeding in third trimester and placenta abruption happen in 0.5%–1% of births.,,
Intrauterine growth restriction (IUGR) was defined as a condition that foetal growth is not completed. It is birth weight below the 10th percentile of the national standard, and severe IUGR is under the 5th percentile the national standard for gestational age. The possible aetiology is including placental insufficiency, mother malnutrition, uterus inflammation, diabetes mellitus type 2, hypertension, preeclampsia, maternal smoking, obesity and hypercholesterolemia.,
Some studies showed that placenta abruption can be led to IUGR, but conflicting results have been reported concerning between placenta abruption and the risk of IUGR. Some of the studies have determined an increased risk of the placenta abruption with IUGR,, and others did not report.,
However, to the best of our knowledge, the effect of placenta abruption on the risk of IUGR has not been adequately evaluated in a meta-analysis and systematic review manner. Therefore, the objective of the present meta-analysis was to identify all the eligible studies to assess the effect of placenta abruption on the risk of IUGR.
| Materials and Methods|| |
This meta-analysis determined the effect of placenta abruption on the risk of IUGR. According to the PRISMA guidelines, this meta-analysis was carried out. We have done the search for relevant studies in major electronic databases including: Web of Science, PubMed and Scopus irrespective to maternal age, IUGR severity, race, country, study date and language of surveys. A total of seven papers were included for this meta-analysis.
Criteria for including and excluding studies
All observational studies including cohort and case–control studies that reported the effect of placenta abruption on the risk of IUGR by systematic search were included in the study. The full texts were reviewed by authors and duplicated results; letters to editor and review articles were deleted.
Two investigators independently conducted the complete search strategy in PubMed, Scopus and Web of Science databases using keywords: (placenta abruption or placental abruption or abruptio placenta or abruptio placental) and (intrauterine growth restriction OR IUGR). The following search was conducted up to January 2018. Furthermore, references-related systematic reviews were searched for relevant studies.
Data collection and validity assessment
Initial searches were conducted by two independent authors and disagreements were resolved. There were the three stages in data extraction including title, abstract and full paper review. The included data were publication's year, first author, odds ratio (OR) and their associated 95% confidence intervals (CIs), country, study design, sample size, adjustment, age (mean or range) and quality of studies.
The qualities of surveys were evaluated by the Newcastle–Ottawa Scale (NOS). After scoring, the articles were categorised into two groups: low-quality surveys (scoring <7 points) and high-quality surveys (scoring ≥7 points).
Heterogeneity in included studies was explored by I2 statistic. The low heterogeneity was reported by I2 value of 0%–30%, moderate heterogeneity by I2 value of 30%–60% and substantial heterogeneity by I2 value of >60%. Data were analysed, and the outcomes were presented by random effect model. The publication bias tests were Begg and Egger's in extracted studies. All meta-analysis was carried out using Stata software version 13 (Stata Corp, College Station, TX, USA).
| Results|| |
Description of studies
A total of 551 references were identified by initial search until January 2018. After removing duplicate publications, 303 articles were identified for assessing the title and abstract. Then, 23 references were considered for reading full paper. In the end, a total of seven references were remained for this meta-analysis [Figure 1]. We identified two cohort studies, and 5 case–control studies,,,, with 35,201 participants. All surveys were published in the English language [Table 1].
|Figure 1: Flow of information through the different phases of the systematic review.|
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Effects of exposure
In this study, the effects of placenta abruption on IUGR were reported in [Figure 2] based on epidemiological studies. The result of the study showed that placenta abruption has a significant effect on risk of IUGR (2.06; 95% CI: 1.57, 2.55) based on OR estimate obtained from case–control and cohort studies. The results reported of the measure of effect was homogeneous (I2 = 0.0%).
|Figure 2: Forest plot of the effect of placenta abruption on the risk of intrauterine growth restriction.|
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We carried out subgroup analysis to design of studies in [Table 2]. Based on OR estimates, the effect of placenta abruption on the risk of IUGR in case–control and cohort studies was (1.88; 95% CI: 1.0, 2.77) and (2.24; 95% CI: 1.60, 2.88), respectively. The results of the study showed that placenta abruption has the significant effect on the risk of IUGR in cohort studies. There was no heterogeneity in cohort studies.
|Table 2: Results of subgroup analysis of the placenta abruption on the risk of intrauterine growth restriction|
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For assessing publication bias, the Begg's and Egger's test was carried out in the present meta-analysis (P = 0.652 and P = 0.670, respectively). The studies scattered nearly symmetrically.
Quality of the studies
In the present meta-analysis except one study, the rest studies had high-quality based on NOS scale [Table 1].
| Discussion|| |
According to the literature, no systematic review and meta-analysis have been conducted for assessing the effect of placenta abruption on IUGR. This systematic review reported that, based on observational studies, the placenta abruption was a risk factor for IUGR. Pooled estimate of included studies showed that overall odds of IUGR in placenta abruption cases compared control groups were 2.06 (95% CI: 1.57, 2.55). These results showed that the measure of effect was homogeneous. When was done subgroup analysis to the design of studies, placenta abruption has the significant effect on risk of IUGR.
Placental abruption has been determined as perinatal hazards that can be led to maternal and neonatal complications. Placenta abruption is responsible about 12% of all perinatal deaths. The effect of placenta abruption on perinatal outcomes is including blood loss, pregnancy-induced hypertension, polyhydramnios, premature delivery, IUGR, non-vertex presentation, the risk of perinatal asphyxia, the risk of sepsis and hyperbilirubinemia. Several surveys reported that the adverse neonatal outcomes including low Apgar scores, IUGR and perinatal mortality complicated with placental abruption. The significant effect placenta abruption with IUGR further supports the abnormal foetoplacental relationship with abnormal vascularity.
The mechanisms of the effect of placenta abruption on IUGR still not clear. IUGR can be caused by continues response to the chronic effects on the placenta damage. It has been suggested that IUGR is related to uteroplacental blood perfusion insufficiency and ischaemia such as the presence of placenta infarct. However, placental abruption and IUGR may be considered placenta dysfunction and have a shared placenta cause. In addition, genetic factors may be affected on foetal growth restriction associated with placenta abruption, maybe through compromise of placental function.
However, the present study has some limitations. (a) Included study was conducted at settings with different countries so that from seven included study, two studies conducted in Asian, two in the USA and three in Europe; therefore, there was the unreliability in finding to all settings. (b) All studies were reported crude results; hence, this might introduce data bias in our results. (c) Data that were provided by enrolled studies were not sufficient to perform some subgroup analysis based on confounding variables.
| Conclusion|| |
Our findings showed based on reports in epidemiological studies that placenta abruption increased the risk of IUGR more than two-fold. Therefore, placenta abruption is a risk factor for IUGR. These results propose that prevention by identifying risk factors and early diagnosis to reduce the occurrence of placental abruption can decrease the risk of IUGR.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]