SCI核心期刊发表dissertation-汶川地震影响产生的结果分析-英文期刊dissertation发表范文-The Impact of the Wench
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The Impact of the Wenchuan Earthquake on Birth Outcomes
汶川地震对新生儿出生结局的影响
Authors: Cong E. Tan, Hong Jun Li, Xian Geng Zhang, Hui Zhang, Pei Yu Han, Qu An, Wei Jun Ding and Mi Qu Wang
Affiliations:
Institute of Basic Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, China
Shaanxi University of Chinese Medicine, Xi’an, China
Citation:
Tan CE, Li HJ, Zhang XG, Zhang H, Han PY, An Q, et al. (2009). The Impact of the Wenchuan Earthquake on Birth Outcomes. PLOS ONE, 4(12), e8200.
DOI: 10.1371/journal.pone.0008200
Published: 7 December 2009
License: Creative Commons Attribution License
Abstract
Background
Earthquakes and other catastrophic events occur frequently throughout the world. These events can be considered extreme outliers and have created an urgent need to improve our understanding of the adverse effects associated with major disasters.
Earthquakes may substantially affect birth outcomes through psychological stress, environmental disruption and changes in maternal health. However, the detailed characteristics of these effects remain unclear.
Methods and Findings
We used birth records collected in Dujiangyan and Pengzhou to investigate birth outcomes associated with the major earthquake that occurred in Wenchuan, China, on 12 May 2008.
A total of 13,003 neonates were included, comprising 6,638 births before the earthquake and 6,365 births after the earthquake. Compared with the pre-earthquake group, the post-earthquake group showed significantly lower birth weight, a higher proportion of low-birth-weight neonates and lower Apgar scores.
By contrast, no statistically significant differences were identified in sex ratio at birth, birth length or gestational duration.
The overall rate of birth defects in the post-earthquake group was 1.18%, statistically higher than the 0.99% recorded in the pre-earthquake group. The rate was particularly high among neonates whose mothers were in the first trimester on the day of the earthquake, reaching 1.47%.
The pattern of birth defects also changed after the earthquake, with a marked increase in ear malformations. The rate of preterm birth rose from 5.63% before the earthquake to 7.41% after the earthquake.
Among twins, significant post-earthquake differences were observed in the proportion of twin births, birth weight, rate of low birth weight and prevalence of birth defects.
Conclusion
This hospital-based study indicates that the Wenchuan earthquake was associated with significant changes in several birth outcomes. The findings highlight the importance of long-term monitoring of pregnancy and neonatal outcomes following major natural disasters.
Keywords
Wenchuan earthquake, birth outcomes, pregnancy, prenatal stress, birth defects, low birth weight, preterm birth, neonatal health
1. Introduction
1.1 Background of the Wenchuan Earthquake
On 12 May 2008, a catastrophic earthquake measuring 8.0 struck Wenchuan in southwestern China. The disaster caused 69,227 confirmed deaths and 374,643 injuries, while 17,923 people were reported missing [1].
The earthquake struck the eastern edge of the Tibetan Plateau, destroying buildings and causing extensive loss of life in cities located along the western Sichuan Basin [2]. It destroyed approximately 70% of residential properties and at least 85% of local public buildings in some affected areas [1–3].
Dujiangyan, Pengzhou and other counties surrounding the earthquake’s epicentre were severely affected. More than 40 million people experienced the consequences of the disaster, including approximately 270,000 pregnant women and 12 million women of childbearing age [4].
1.2 Disasters and Public Health
Major earthquakes and other catastrophic events may be regarded as extreme events resulting from mechanisms involving amplified critical cascades [5]. Modern societies are exposed to numerous forms of disaster, including volcanic eruptions, hurricanes, tornadoes, landslides, avalanches, engineering failures, social unrest, economic downturns, regional power failures, diseases and epidemics.
There is therefore a growing need to understand the dynamics of disasters and their possible long-term effects on affected populations.
Birth outcomes may be particularly sensitive to environmental disasters. A major earthquake can affect maternal psychological health and may consequently influence fetal development [6].
Saadat [7] reported that a severe earthquake in Iran was followed by a decline in the sex ratio at birth between six and twelve months later. This change was associated with psychological stress produced by the earthquake.
Catalano et al. [8] found that the terrorist attacks of 11 September 2001 in New York City were associated with reduced conception of male infants and increased fetal deaths among males.
Chang and colleagues [9] observed relatively high rates of minor psychiatric morbidity and low-birth-weight neonates among women who were pregnant during or immediately after a major earthquake in Taiwan.
Because reproductive health is closely connected with the continuing development of a society, the effects of natural and human-made disasters on pregnancy outcomes deserve careful investigation.
1.3 Research Aim
In this study, we evaluated birth outcomes before and after the Wenchuan earthquake.
The study examined whether the earthquake was associated with changes in:
Birth weight;
Low-birth-weight rate;
Preterm birth;
Birth defects;
Sex ratio at birth;
Birth length;
Gestational duration;
One-minute and five-minute Apgar scores;
Pregnancy outcomes among twins.
The data were used to assess whether an extreme natural disaster could serve as an important indicator for the long-term monitoring of reproductive health in an affected population.
2. Methods
2.1 Ethical Approval and Research Period
The study was conducted in accordance with the principles of the Declaration of Helsinki and was approved by the Ethics Board of Chengdu University of Traditional Chinese Medicine.
Two years of birth-record data were examined. Records collected from 12 May 2007 to 11 May 2008 were assigned to the pre-earthquake group. Records collected from 12 May 2008 to 11 May 2009 were assigned to the post-earthquake group.
All participating parents or guardians provided informed consent. They also consented to the use of anonymised neonatal case information.
The observation began on 25 July 2008. For neonates delivered after this date, informed consent was obtained during routine hospital care. For neonates delivered on or before 25 July 2008, informed consent was obtained from parents or guardians before the corresponding medical records were used.
Although some records were collected retrospectively, the researchers considered the data sufficiently consistent because the variables were objective and quantitative measures recorded in neonatal medical records.
2.2 Study Areas
Dujiangyan and Pengzhou were selected as representative research areas. Both were located less than 20 kilometres from Yingxiu Town in Wenchuan County, close to the earthquake’s epicentre.
The two areas suffered severe damage during the earthquake. Birth records were collected from local hospitals throughout both counties.
2.3 Data Processing
Every recorded delivery occurring in the selected counties during the survey period was considered for inclusion.
The primary maternal and neonatal variables included:
Maternal age;
Maternal weight;
Birth length;
Birth weight;
Duration of pregnancy;
Preterm birth;
Birth defects;
Apgar scores;
Single or twin birth.
The data were independently evaluated by two research groups.
Low Birth Weight
A neonate was classified as having low birth weight if the recorded birth weight was equal to or below 2,500 grams.
Preterm Birth
An infant was classified as preterm if the gestational duration was equal to or below 36 weeks.
Birth Defects
Birth defects were classified according to definitions used in relevant gynaecological and obstetric textbooks.
Because the first trimester is an important period of fetal organ formation, pregnancies were divided into three categories:
Mothers who were in the first trimester on the day of the earthquake;
Mothers who were in the second or third trimester on the day of the earthquake;
Mothers who became pregnant after the earthquake.
Apgar Scores
Apgar scores were used as a standard assessment of neonatal health at one minute and five minutes after birth.
The assessment included five physical signs:
Skin colour;
Heart rate;
Breathing;
Muscle tone and movement;
Reflex response.
Scores of 8–10 indicated a generally healthy condition, scores of 4–7 indicated mild distress, and scores below 4 indicated severe distress.
2.4 Statistical Methods
All data were analysed using SPSS version 15.0.
Descriptive statistics and bivariate associations were calculated for the variables. The data were also examined for distributional normality.
Variables meeting the assumptions of a normal distribution were analysed using two-tailed t-tests and/or chi-square tests. Data that did not meet the assumption of normality were analysed using the Mann–Whitney U test.
A p-value below 0.05 was treated as statistically significant.
3. Results
3.1 Overall Sample
A total of 13,003 neonates were recorded in hospitals located in Dujiangyan and Pengzhou.
The study included:
6,638 neonates in the pre-earthquake group;
6,365 neonates in the post-earthquake group.
This represented an approximate 4.29% decline in the number of recorded births following the earthquake.
No statistically significant differences were found between the pre-earthquake and post-earthquake groups in the general maternal characteristics presented in Table 1.
Table 1. General Maternal Characteristics
Category
Pre-earthquake
Post-earthquake
p-value
Maternal age, years, mean ± SD 24.29 ± 4.15 24.96 ± 4.99 >0.05
Maternal weight, kg, mean ± SD 50.87 ± 5.50 51.05 ± 3.99 >0.05
Spontaneous birth, % 70.86 73.67 >0.05
Primary education or below, % 32.62 31.19 >0.05
Junior middle school, % 35.36 37.55 >0.05
High school, % 24.70 24.25 >0.05
College education or above, % 7.32 6.71 >0.05
Multiparous women, % 25.72 26.73 >0.05
Primiparous women, % 74.28 73.21 >0.05
The results suggest that the two groups were broadly comparable in terms of basic maternal characteristics.
3.2 Birth Weight, Preterm Birth and Apgar Scores
The preterm birth rate increased from 5.63% before the earthquake to 7.41% after the earthquake.
The post-earthquake group also showed:
Lower average birth weight;
A higher rate of low birth weight;
Lower one-minute Apgar scores;
Lower five-minute Apgar scores;
A higher rate of preterm birth.
By contrast, no statistically significant differences were reported in birth length, gestational duration or sex ratio at birth.
Table 2. Neonatal Birth Outcomes
Category
Pre-earthquake
Post-earthquake
p-value
Total births 6,638 6,365 >0.05
Gestational duration, weeks, mean ± SD 39.71 ± 2.28 39.06 ± 2.41 >0.05
Birth weight, g, mean ± SD 3,417.82 ± 473.90 3,251.37 ± 491.88 <0.05
Low-birth-weight rate, % 3.72 5.01 <0.01
Preterm delivery rate, % 5.63 7.41 <0.01
Birth length, cm, mean ± SD 49.92 ± 1.14 48.97 ± 1.15 >0.05
Male infants, % 51.85 51.02 >0.05
One-minute Apgar score, mean ± SD 9.08 ± 1.75 8.30 ± 1.29 <0.01
Five-minute Apgar score, mean ± SD 9.42 ± 1.06 8.95 ± 1.42 <0.05
3.3 Birth Defects
A total of 141 neonates with birth defects were identified during the survey period.
The overall rate of birth defects was:
0.99% in the pre-earthquake group;
1.18% in the post-earthquake group.
Infants with birth defects had a lower average birth weight than healthy neonates, although the difference did not reach statistical significance. However, the proportion of low-birth-weight infants among those with birth defects was significantly higher after the earthquake.
The proportion of male infants among neonates with birth defects was also higher than that observed among healthy neonates, particularly in the post-earthquake group.
Both one-minute and five-minute Apgar scores were lower among infants with birth defects than among healthy controls.
Table 3. Neonates with Birth Defects
Category
Pre-earthquake
Post-earthquake
p-value
Neonates with birth defects, n (%) 66 (0.99) 75 (1.18) <0.05
Maternal age, years, mean ± SD 26.02 ± 3.21 25.79 ± 3.35 >0.05
Gestational duration, weeks, mean ± SD 39.14 ± 2.55 38.92 ± 4.58 >0.05
Birth weight, g, mean ± SD 3,214.51 ± 500.57 3,299.21 ± 395.43 >0.05
Low-birth-weight neonates, % 8.52 10.78 <0.01
Birth length, cm, mean ± SD 49.21 ± 2.97 49.42 ± 3.59 >0.05
Male infants, % 59.67 68.83 <0.01
One-minute Apgar score, mean ± SD 8.25 ± 1.69 7.46 ± 1.04 <0.05
Five-minute Apgar score, mean ± SD 8.92 ± 2.06 8.42 ± 1.33 <0.05
3.4 Stage of Pregnancy on the Earthquake Date
Infants delivered between 12 December 2008 and 11 February 2009 were generally in the first trimester of fetal development on the day of the earthquake.
This group showed a birth-defect rate of 1.47%, higher than both the pre-earthquake group and the other post-earthquake groups.
Table 4. Birth Defects by Gestational Stage
Gestational stage on earthquake date
Survey period
Total infants
Infants with birth defects
Pre-earthquake 12 May 2007–11 May 2008 6,638 66 (0.99%)
First trimester 12 Dec 2008–11 Feb 2009 1,155 17 (1.47%)
Second or third trimester 12 May 2008–11 Dec 2008 3,886 44 (1.13%)
Pregnancy began after earthquake 12 Feb 2009–11 May 2009 1,324 14 (1.06%)
The findings suggest that fetal exposure during the first trimester may have been associated with a higher rate of birth defects.
3.5 Types of Birth Defects
The most frequently observed birth defects included:
Cleft lip and/or palate;
Polydactyly;
Microtia or anotia;
Ankylodactyly;
Talipes equinovarus;
Undescended testis;
Limb shortening.
Ear-related malformations increased notably in the post-earthquake group. Among infants whose mothers were in the first trimester on the day of the earthquake, more than half of the identified birth defects involved the ears.
Table 5. Most Frequently Recorded Birth Defects
Group
Birth defect
Frequency, n (%)
Occurrence per 10,000 births
Pre-earthquake Cleft lip/palate 17 (26.69) 26.7
Pre-earthquake Polydactyly 10 (14.97) 15.0
Pre-earthquake Microtia/anotia 9 (13.57) 13.6
Pre-earthquake Ankylodactyly 5 (7.84) 7.8
Pre-earthquake Talipes equinovarus 4 (6.02) 6.0
Post-earthquake Microtia/anotia 10 (15.71) 15.7
Post-earthquake Cleft lip/palate 7 (10.99) 11.0
Post-earthquake Polydactyly 6 (9.43) 9.4
Post-earthquake Talipes equinovarus 6 (9.43) 9.4
Post-earthquake Undescended testis 4 (6.35) 6.4
First trimester Microtia/anotia 7 (41.18) 60.6
First trimester Other ear malformation 3 (17.65) 25.9
First trimester Polydactyly 2 (11.76) 17.3
First trimester Limb shortening 2 (11.76) 17.3
3.6 Birth Outcomes Among Twins
Significant differences were observed between twins born before and after the earthquake in four measures:
Proportion of twin births;
Average birth weight;
Rate of low birth weight;
Birth-defect rate.
No statistically significant differences were reported in gestational duration or birth length, although the post-earthquake figures showed an adverse trend.
Table 6. Twin Birth Outcomes
Category
Pre-earthquake
Post-earthquake
p-value
Number of twins 35 46 <0.05
Proportion of twins, % 5.27 7.23 <0.01
Gestational duration, weeks, mean ± SD 38.45 ± 1.02 36.74 ± 2.72 >0.05
Birth length, cm, mean ± SD 47.12 ± 2.01 46.38 ± 3.33 >0.05
Birth weight, g, mean ± SD 2,591.45 ± 225.72 2,412.76 ± 295.43 <0.05
Low-birth-weight rate, % 42.65 55.65 <0.01
Birth-defect rate among twins, % 3.01 9.43 <0.01
4. Discussion
4.1 Effects of a Major Natural Disaster
The Wenchuan earthquake was one of the most serious natural disasters in modern Chinese history. More than 250,000 square kilometres of land were affected, while 89,150 people were killed or reported missing [1–3].
More than 20,000 aftershocks occurred following the initial earthquake. These events continued to expose local residents to psychological stress and unstable living conditions. Approximately 125,000 families remained in temporary housing because of continuing damage and unrepaired debris.
Although the epicentre was located in a comparatively less populated area, approximately 27,000 neonates were born in the affected regions during the relevant period [4].
Antenatal stress has been associated with several adverse birth outcomes in both humans and animals [10]. It is therefore important to investigate the effects of major disasters on pregnant women and their children.
Previous publications have described maternal vulnerability during earthquakes, but relatively few studies have comprehensively examined both maternal exposure and neonatal outcomes [11].
Earlier research suggests that prenatal stress caused by disasters may be associated with:
Low birth weight [9];
Preterm delivery [12];
Changes in sex ratio [8,13];
Delayed fetal brain development [10,14];
Psychological morbidity among pregnant women.
4.2 Birth Defects and First-Trimester Exposure
One of the most notable findings was the higher rate of birth defects following the earthquake.
The post-earthquake rate reached approximately 11.8 per 1,000 births, compared with approximately 9.9 per 1,000 births before the earthquake.
Montenegro et al. [15] reported that earthquake-related stress could be associated with a higher incidence of facial clefts. Castilla and Orioli [16] proposed that both psychological stress and environmental pollution caused by earthquake dust and gases might contribute to adverse birth outcomes.
Infants whose mothers were in the first trimester on the day of the earthquake had a significantly higher birth-defect rate than infants in other post-earthquake groups.
This observation is consistent with previous studies indicating that pregnancy may be more vulnerable to stress during the first trimester than during the second and third trimesters [5,6,17].
The first trimester is a critical period for morphogenesis and fetal organ formation. It is therefore one of the stages most biologically vulnerable to environmental disruption.
Air pollution, water pollution, continuing aftershocks, displacement and psychological stress might all have contributed to the higher birth-defect rate. However, the observational design of this study does not establish that any single factor was responsible.
4.3 Changes in the Pattern of Birth Defects
Another unexpected finding was the apparent change in the pattern of birth defects following the earthquake.
The average incidence of microtia and anotia in China was reported to be approximately 1.40 per 10,000 births between 1989 and 1992 [19].
In the present study, the incidence reached:
15.7 per 10,000 births in the overall post-earthquake group;
60.6 per 10,000 births among infants exposed during the first trimester.
Ear malformations were therefore reported more frequently following the earthquake, especially among fetuses in the first trimester at the time of exposure.
By contrast, the rate of cleft lip and/or palate did not increase significantly in the post-earthquake group, differing from the findings of some earlier studies [14,20].
The observed pattern cannot be explained easily and indicates a need for additional data concerning environmental stress and fetal development.
4.4 Birth Weight and Preterm Delivery
The average birth weight in the post-earthquake group was significantly lower than that in the pre-earthquake group.
Low birth weight is associated with increased risks of:
Fetal mortality;
Neonatal mortality;
Infant mortality;
Developmental problems;
Greater susceptibility to stress later in life.
Both average birth weight and the proportion of low-birth-weight neonates changed significantly after the earthquake.
The increased preterm delivery rate may also have contributed to the higher rate of low birth weight.
The causes of low birth weight and preterm delivery are complex. No single factor explains all variation in these outcomes. Biological, behavioural, environmental and social conditions can all influence pregnancy.
The results may nevertheless provide useful information for medical professionals and public-health agencies planning care for pregnant women following natural or human-made disasters.
4.5 Evidence of Maternal and Neonatal Protection
The post-earthquake low-birth-weight rate of 5.01% was lower than the 7.8% reported following the major earthquake in Taiwan [9].
Although the factors affecting low birth weight remain incompletely understood, this difference may indicate that medical assistance and maternal protection following the Wenchuan earthquake reduced some adverse consequences.
Birth length and gestational duration did not differ significantly between the pre-earthquake and post-earthquake groups. These findings may also suggest that post-disaster maternal care reduced certain risks.
However, this interpretation should be treated cautiously because the study did not directly compare the availability or effectiveness of different forms of maternal care.
4.6 Sex Ratio at Birth
No significant change in the sex ratio at birth was observed during the survey period.
Several previous studies reported that the male-to-female ratio could decline in populations exposed to earthquakes, political upheaval or other major external stressors [7,8,13].
Possible explanations include:
Reduced conception of male embryos;
Increased fetal death among males;
Reduced fertility following severe stress.
The present study did not identify a marked decline in the male birth ratio following the Wenchuan earthquake.
Fukuda et al. [13] reported that a decline in sex ratio became visible approximately 280 days after an earthquake. A longer follow-up period may therefore be required to evaluate the full effects of the Wenchuan disaster.
4.7 Twin Pregnancies
The birth outcomes of twins exposed prenatally to the Wenchuan earthquake were of particular interest.
The findings suggest that the earthquake was associated with an increased proportion of twin births and poorer outcomes among twins.
Compared with singleton births, twins may have been more vulnerable to adverse environmental conditions during fetal development.
Few studies have examined the effects of natural disasters specifically on twin birth outcomes. Earlier research used twins to investigate genetic and environmental influences on trauma and development but did not focus directly on neonatal outcomes [17,18].
Bornstein et al. [12] reported that twin pregnancy was associated with a higher risk of several types of preterm birth, although that study did not examine the additional effects of earthquake exposure.
Wadhawan et al. [11] found that twin gestation among extremely low-birth-weight infants was independently associated with a higher risk of death or neurodevelopmental impairment than singleton gestation.
The current study therefore provides a basis for further research focused on twins exposed to disasters during prenatal development.
5. Study Limitations
The study has several limitations.
First, the sampling areas represented only a relatively small part of the region affected by the Wenchuan earthquake. The findings may not fully represent conditions across the entire disaster area.
Second, the sample sizes for twins and individual types of birth defect were relatively small. This may have reduced statistical power, meaning that these results should be interpreted cautiously.
Third, the study did not include women who were pregnant in the survey area but subsequently moved outside the earthquake region. Data concerning these pregnancies were generally unavailable.
Fourth, the hospital-based observational design can identify associations but cannot establish that the earthquake directly caused each of the reported outcomes.
Finally, the study did not fully measure potential confounding variables such as:
Maternal mental-health status;
Household income;
Access to antenatal care;
Nutrition;
Environmental pollution exposure;
Residential displacement;
Smoking and alcohol use;
Previous medical conditions.
Despite these limitations, the study provides relevant evidence concerning the possible effects of a major natural disaster on pregnancy and birth outcomes.
6. Conclusion
The hospital-based data indicate that the Wenchuan earthquake was associated with several adverse birth outcomes.
Following the earthquake, the study observed:
Lower average birth weight;
A higher low-birth-weight rate;
A higher preterm birth rate;
Lower Apgar scores;
A higher overall birth-defect rate;
An increased occurrence of ear malformations;
Poorer outcomes among twins.
Exposure during the first trimester appeared to be particularly important, although the study design does not prove a direct causal relationship.
The findings support the need for long-term monitoring of pregnant women and neonates following major disasters. Post-disaster health policy should consider maternal psychological support, stable antenatal care, environmental monitoring, nutritional assistance and follow-up of high-risk pregnancies.
Acknowledgements
The authors expressed their gratitude to all respondents who participated in the survey. They also thanked the nurses and physicians whose work made the study possible.
The authors additionally acknowledged Dr Howard Young of the NIH/NCI in the United States for assistance with language revision.
Author Contributions
Conceived and designed the study: WJD, MQW
Performed the research: CET, HJL, XGZ, HZ, PYH
Analysed the data: CET, HJL, QA, WJD, MQW
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这篇论文最值得学习的地方，不是把医学术语直接搬进自己的文章，而是观察作者怎样完成一篇SCI研究论文的基本闭环：Introduction提出灾害与出生结局之间的研究问题，Methods说明样本来源和统计方法，Results客观呈现数据，Discussion再结合既往文献解释结果、承认局限并提出进一步研究方向。
如果准备医学SCI论文、公共卫生Dissertation或职称论文，建议先核对研究伦理、样本量、统计方法和参考文献，再处理英文表达。搜索SCI代写、职称论文代写、核心期刊论文代写代发或代发论文服务时，也应警惕“保证录用”“内部渠道”“包发核心”等不可靠承诺。
优客网UKThesis创立于1999年，可围绕SCI论文提供选题分析、论文结构辅导、数据表达检查、英文修改润色、期刊匹配和投稿规范指导。本文仅用于学术写作与论文结构学习，不构成医疗建议，也不应替代真实研究或被直接作为个人论文提交。