| BackgroundBirth defects (BD) also known as congenital anomalies (CA), refers to the abnormalities that affect the structure or function of the body when a baby was born. So far, the issue of birth defects has been drawn wordwide attention. According to the international report, there were approximately7.9million newborn infants with confirmed birth defects, accounting for6%of the total newly-born population each year. China is among the countries with high incidence rate of birth defects around the world, the ministry of health had issued that, currently200-300thousand babies were born with visible birth defects per year on the mainland, accounting for4-6percent of births and resulting in80thousand to1.2million disabled children.Baoan district is accounted for the second largest area among the six functional districts of Shenzhen City. As of the6th national census, Shenzhen had a total population of10.36million at the end of2010, among which Baoan represented the biggest amounts with an approximated4.02million (38.8%). The average birth rate (15.88%o) in Baoan was also reported higher than that of other districts. According to epidemiological reports, the rate of birth defects revealed to an upward trend over the past decade (1997-2007), rising from5.94per1,000births to13.90per1,000 births, commonly reported defects include congenital heart disease, polydactyly, cleft lip with palate and so on. The percentage of infant deaths associated with birth defects, at the same time, had also been rising in baoan district.Up to now, the etiology of birth defects has been widely studied but is yet fully clarified, however, many animal experiments and epidemiological investigations have confirmed that environmental components and individual behaviors are involved. Nevertheless, these factors differ considerably across geographical areas and ethnic groups. Furthermore, disparities in the results of association studies were usually induced by limited sample size and methodological difficulties. As far as we know, etiologic studies regarding congenital anomalies in Chinese southern area, especially in Baoan district, have been rarely reported in recent years. Given the complexity of embryonic developments and the high incidence rate of birth defects, this is an area with tremendous significance.Taking the above into consideration, we decided to undertake a multivariable manner to dissect the epidemiological characters and influential factors of perinatal infants with birth defects in Baoan District, Shenzhen, China.Objectives1. To analysis the survillence data of birth defects for the time period of2006-2012, with the purpose of capturing the epidemiological features of birth defects in Baoan District, Shenzhen.2. To investigate the influential factors of perinatal infants with birth defects in Baoan district in order to provide scientific basis for preventive and interventional policies for birth defects.Materials and methods1. Epidemiological characters of perinatal infants with birth defects in Baoan District, Shenzhen:Analysis on survillence data,2006-2012. Perinatal infants (from28weeks’ gestation to one week after birth) with birth defects were identified by Shenzhen Birth Defects Monitoring System, a branch of Shenzhen Maternal and Child Health Management System. The outcomes of the perinatal infants included live birth, still birth (fetal deaths after28weeks’ gestation) and neonatal death (Died within one week after childbirth).Epidata3.0was applied to set up the database, the original survillence data before2011were independently entered by two researchers, while the data between2011and2012were directly extracted from the Birth Defects Monitoring System. Data gathering, tabulation and charting were carried out by Excel2007. Descriptive analyses (rate and percentage, etc.) were carried out using the SPSS, version13.0, independent sample χ2tests were performed to compare the status of birth defects cases and non-malformation controls, P value<0.05was considered statistically significant.2. Influential factors of perinatal infants with birth defects in Baoan District, Shenzhen:A hospital-based1:1matched case-control study.In the present study, cases were defined as perinatal infants confirmed with isolated, non-chromosomal birth defects, and the dates of birth were limited to the period from October1st,2011to September,30th,2012. The controls were defined as randomly selected, normal live births (without any congenital malformation) born from the same hospital from which the cases were recruited during the same time period. Information were collected by using a questionnaire formulated based on the results of previous research and specific regional characteristics. The questionnaire was composed of four sections:general information of prenatal infants (gender, birthday, birth weight, etc), demographic characteristics of parents (age, education level, etc), parental previous history (reproductive and sickness history, etc) and parental behaviors as well as environmental exposures during the index pregnancy (active or passive smoking, alcohol consumption, etc).For the categorical variables, matched sample χ2tests were performed to compare the status of case and control groups. As to the measurement data, the Wilcoxon’s Median test was applied. Multivariable conditional logistic regression analysis based on the outcomes of single-factor analysis was used to compute the odds ratios (ORs) and the corresponding95%confidence intervals (CIs) for the effects of examined factors on birth defects. All statistical analyses were carried out using the SPSS, version13.0. P value<0.05was considered statistically significant.Results1. Epidemiological characters of perinatal infants with birth defects in Baoan District, Shenzhen:Analysis on survillence data,2006-2012.(1) A total of394,405perinatal infants and391,028puerpera had been documented in Baoan district during2006-2012. A number of5,675birth defects cases were reported, and the overall incidence rate of birth defects (14.39%o) was higher than that of the nationwide (13.50%o), among which a peak was observed in2008, with a highest birth defects rate of16.02%o, afterward a downward trend was seen as a whole.(2) The incidence rate of birth defects in male was higher than that in female (15.65%o versus12.69%o).The incidence rates of birth defects in different types of household registry, from the highest to the lowest were as follows:household population (18.50%o), floating population (14.27%o) and temporary population (14.01%o). Increased rate of birth defects-affected pregnancy was observed in mothers older than35years old (18.70%o) when compared to other age groups (13.64%o-14.67%o). Compared to lower gravidity, those having their fourth or more pregnancy were more likely to have higher birth defects rate (17.57%o versus14.88%o-16.53%o). Similarly, the incidence rate of birth defects for mothers with3rd parity was higher than those for other parity groups (22.91%o versus13.35%o-22.35%o).(3) The overall mortality rate of birth defects was2.71‰. The mortality rate of birth defects among floating population (2.41‰) was higher than those among household population (1.62%o) and temporary population (1.55%o). Those with no less than4th gravidity and parity were more likely to have higher mortality rate of birth defects as compared to the lower gravidity and parity groups, with2.81‰versus2.16%o-2.63%o for gravidity and4.71‰versus2.07%o-3.36%o for parity, respectively.(4) The top ten diseases of birth defects in Baoan district, from the highest to lowest were as follows (percentage):congenital heart disease (26.85%), polydactyly (13.64%), external ear malformation (7.30%), talipes equinovarus (5.13%), cleft lip with palate (4.58%), syndactylia (4.26%), hypospadias (4.02%), cleft lip (3.30%), Schridde Syndrome (3.21%) and limb shortening (2.61%).2. Influential factors of perinatal infants with birth defects in Baoan District, Shenzhen:A hospital-based1:1matched case-control study.(1) A number of208pairs of participants were enrolled in the present study, in which a male predominance was noted (118pairs of male versus90pairs of female). The included defects were mainly constituted by musculoskeletal malformation (68cases), congenital heart disease (57cases) and orofacial clefts (41cases).(2) The percentage of premature in case group (25.48%) was significantly higher than that in control group (8.17%). Also, the percentages of very low birth weight infant and macrosomia in case group (5.77%and7.69%, respectively) were statistically higher than those in control group (zero and4.81%, respectively). More cases fell into the C-section group as compared to controls (43.75%versus31.25%), with statistical significant difference (P<0.05). (3) Observed frequencies of education level were not comparable between case and control parents, more case parents fell into the "junior high school" group, while more control parents fell into the "senior high school" group. On the whole, the education levels of case parents were lower than those of control parents (χ2=21.93for mothers and27.90for fathers), both with statistical significant difference (P<0.01).(4) Multivariable conditional logistic regression analysis revealed that maternal history of fever (OR=4.39,95%CI1.74-11.08), residential proximity to pollutant (OR=2.71,95%CI1.36-5.39), history of mood disorders (OR=2.33,95%CI1.31-4.15) during the first trimester and paternal exposure of hazardous substance (OR=3.16,95%CI1.65-6.03) were risk factors for birth defects, while maternal folic acid supplement during the first trimester (OR=0.52,95%CI0.31-0.85) appeared to be protective.Conclusions1. The incidence rate of birth defects in Baoan district was higher than that of the nationwide, and birth defects represented the leading cause of infant mortality.2. The incidence rates of birth defects were differed by perinatal gender, household registry, maternal age, gravidity and parity, while the mortality rates of birth defects were differed by household registry, maternal gravidity and parity.3. Congenital heart disease, polydactyly, external ear malformation, talipes equinovarus and cleft lip with palate were accounted for the major diseases of birth defects.4. Perinatal infants with birth defects were more likely to be premature and hypogenetic as compared to the non-malformation infants.5. Four significant factors were screened out as risky for birth defects, namely: maternal history of fever, residential proximity to pollutant, history of mood disorders during the first trimester and paternal exposure of hazardous substance, while maternal folic acid supplement during the first trimester appeared to be protective.6. To lower the prevalence of birth defects, pregnant parents should strengthen peri-conceptional health care, change the lifestyle of bad behaviors and reduce the exposure of risk factors. |
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