| Objective This study aims to explore the method and feasibility of population-based birth defect saveillance, describe the epidemiological characteristics of birth defects in Maanshan, and to examine the association between birth defects and main environmental exposures half a year prior to conception or during the first trimester of pregnancy, so as to provide evidence for birth defect prevention and control.Methods Four maternal and child health centers in Maanshan were chosen and pregnant women who received prenatal care at these centers were selected as the study participants. All participants were asked to complete the self-administered questionnaires to collect such data as demographic characteristics, the couples'environmental exposure half a year prior to conception, pregnant women's environmental exposure in the first trimester of pregnancy and pregnancy outcomes. Comparisons between groups were performed using the chi-squre tests for categorical data. The Logistic regression analysis was adopted to determine the risk and protective factors of birth defects.Results A total of 2 861 pregnancy women participated in the study between October 1st, 2008 and September 30th, 2009. Pregnancy outcomes were obtained from 1 899 of them by the end of March, 2010. The mean age of women was 26.99 years (ranged from 20 to 46) and the mean age of their husbands was 29.80 years (ranged from 21 to 53). As to education level, the proportions of college and above in pregnant women and their husbands were 19.6% and 27.1%, respectively. Among these women, 80.8% had an urban registered residence and 12.6% lived in rural areas. Totally 1 926 birth outcomes were obtained in this cohort study, of which 1 024 (53.2%) were boys and 845 (43.8%) were girls, 1 872 (97.2%) were single birth and 27 pairs were twins. Ages of the live births were ranged from 49 days to 14 months. The overall incidence of adverse pregnant outcomes was 260.64‰and there was significant difference between boys (256.84‰) and girls (216.57‰) (χ2=4.12, p=0.042). The incidence of spontaneous abortion, still birth, preterm delivery, prolonged pregnancy, low birth weight, small for gestational age, macrosomia and birth defects were 18.69‰, 6.75‰, 49.33‰, 14.02‰, 20.77‰, 27.00‰, 105.92‰and 62.31‰, respectively.Of 120 birth defects, 82 (68.3%) were cases required for routine monitoring by national regulations and the incidence was 42.58‰. Additionally, 38 (31.7%) birth defects were cases added to this study, including visual disturbance, hearing loss, congenital scars on the scalp, cheek bone depression and mentally retarded and the total incidence was 19.73‰. One hundred (83.3%) had single defect and 20 (16.7%) had two or more, and the incidences were 51.92‰and 10.38‰, respectively. Among babies with birth defects, 61 (50.8%) were boys and 46 (38.3%) were girls, the incidences were 59.57‰and 54.44‰, respectively. There was no significance difference in the total incidence of birth defects between boys and girls. Difference between boys and girls in the incidence of a certain kind of malformation except the visual disturbance was not significant (χ2=5.56,p=0.018).The leading six birth defects were congenital heart disease (10.90‰), visual disturbance (9.87‰), hemangioma (8.83‰), hearing loss (7.79‰), umbilical hernia (6.23‰) and neural tube defect (4.67‰). The incidence of malformations of circulatory system was 11.94‰, which was the highest among birth defects. Additionally, birth defects of nerves system, head and neck, visual disturbance, hearing loss, as well as hemangioma were numerous, and the incidences were all above 5.00‰. Only 14.2% of birth defects were detected by prenatal diagnosis, of which 20.7% were cases required for routine monitoring by national regulations. All the cases of anencephaly, congenital atresia of rectum and anus, gastroschisis, encephalodysplasia and single umbilical artery were diagnosed before they were born. Part of the cleft lip and palate (3 in 4 cases), renal agenesis (2 in 3 cases), congenital hydrocephalus (1 in 2 cases) and congenital heart disease (3 in 21 cases) were diagnosed before they were born. Of 120 birth defects, 101 (84.2%) survived, 3 (2.5%) died before born, 1 died 7 days after delivery and 15 (12.5%) bad induced labors after diagnosed.The incidence of birth defects was 63.89‰in urban areas, and 54.79‰in rural areas. It was higher in pregnant women over 35 years old than other age groups, although there was no statistically significance (χ2=2.54, p=0.468). Incidences of birth defects were not significantly different in women with different pre-pregnancy body mass index. The incidences of birth defects in the groups of low, middle, high personal month income were 70.58‰, 51.55‰and 34.19‰, respectively with significant difference (χ2=4.25, p=0.039). The incidence of birth defects showed a significant decreasing trend with the increase of husbands'educational level (χ2=7.91, p=0.005). The trend was also found between the incidence and the women's educational level but without significant difference (χ2=2.22, p=0.528).The incidence of birth defects was 142.86‰in women with over 5 previous pregnancies, significantly higher than those of women in other groups with other numbers of pregnancies (χ2=6.04, p=0.049). The incidence in women who had previous adverse pregnancy outcomes (136.36‰), such as induced labor, stillbirth and hydatid pregnancy, was significantly higher than that (58.53‰) of those who didn't have (χ2=8.72, p=0.003). There was no significant difference of incidence between women with different history of spontaneous abortion, induced abortion, infectious disease in obstetrics and gynecology, chronic diseases or genetic diseases. Women who got lower scores in self-evaluation of family atmosphere during the pregnancy tended to have a higher incidence of birth defects (χ2=5.25, p=0.022). The incidence of mother who exposed to pesticide half a year prior to conception (200.00‰) was significantly higher than the incidence (60.67‰) of those who didn't (χ2=4.42, p=0.036). The incidence of mother who used duplicators during the first trimester of pregnancy (90.90‰) was significantly higher than the incidence (56.80‰) of those who didn't (χ2=5.00, p=0.025); The incidence of father who had vibration exposure half a year prior to conception (88.24‰) was significantly higher than the incidence of those who didn't (55.00‰) (χ2=6.07,p=0.014); The incidence of fathers who drank less than three times per week (57.99‰) was significantly lower than the incidence of those who drank over three times per week (114.29‰) (χ2=5.85,p=0.009).By using multivariate logistic regression model, it showed that the risk factors of birth defects included mother had history of adverse pregnancy outcomes (OR=2.44, 95%CI: 1.27~4.68), mothers'exposure to pesticide half a year prior to conception (OR=4.14, 95%CI: 1.33~12.88), mothers used duplicators during the first trimester of pregnancy (OR=2.17, 95%CI: 1.37~3.42). Paternal high education level may be a protect factor for birth defects (OR=0.49, 95%CI: 0.26~0.90).Conclusions Population-based surveillance is an effective way to collect birth defects data. The incidence of birth defects in Maanshan is at a high level and may be resulted from interactions among various factors. Little exposure to harmful environmental factors half a year prior to conception and during pregnancy, as well as the improvement of prenatal diagnosis skills could help a lot in decreasing the birth defects. |
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