中国神经管畸形儿在高发和低发区的性别分布及其出生结局

目的 对中国神经管畸形(NTD)高发和低发区畸形儿的性别及出生结局的流行病学特点进行描述性分析。方法 利用1992～1994年期间“中美预防神经管畸形合作项目”监测资料,按照国际上采用的分类方法,将NTD分为4类,即无脑畸形、脑膨出、高位和低位脊柱裂,再将每一类按照是否合并其他系统畸形分为单纯与合并型,进行高低发区不同类型NTD的男女性别率、性别率比和出生结局的研究,调整城乡、季节和种类,计算调整后的性别率。结果 共监测到326874总产数(包括孕20周及以上的活产、死胎和死产),NTD784例,北方高发区女性无脑畸形发生率(1．30／1000女性总产数)和高位脊柱裂发生率(3．99／1000女性总产数)高于男性(0．66／1000男性总产数和1．66／1000男性总产数),其调整率女性大约是男性的1．8～2．1倍;南方低发区女性高位脊柱裂发生率(0．32／l000女性总产数)和低位脊柱裂发生率(0．21／1000女性总产数)高于男性(0．10／1000男性总产数和0．09／1000男性总产数),其调整率女性是男性的1．3～1．6倍;单纯NTD占全部病例的80％以上,并且单纯NTD女性发生率(2．57／1000女性总产数)显著高于男性(1．40／1000男性总产数),合并型：NTD男女性别发生率(0．36／1000和0．49／1000)的差异无显著性;死产中以高位脊柱裂(44．95％)、活产中以低位脊柱裂(40．64％)占比例较高。死胎中高位脊柱裂和无脑畸形分别占47．06％和35．56％。结论 南方低发区和北方高发区性别率差异随NTD种类而不同,提示可能存在随NTD率增高,女性高位脊柱裂和无脑畸形所占比例有增大趋势。无脑畸形、高位与低位脊柱裂之间可能存在不同的遗传和环境因素。

Sex distribution of neural tube defects and their birth outcome in high- and low-prevalence areas of China

OBJECTIVE: To describe and analyze epidemiological characteristics of babies with neural tube defects (NTD) by sex and birth outcome in a high-prevalence and a low-prevalence areas of China. METHODS: Birth defects surveillance data collected from 1992 through 1994, as a part of the Sino-American cooperative project on NTD prevention, were used to classify NTD as four categories, i.e., anencephaly, encephalocele, high-level and low-level spina bifida according to the sites of lesion (high vs. low level lesion were cervicothoracic and lumbosacral, respectively). Each category was sub-classified, according to single or compound defect, as isolated external defects (including those with NTD only) or multiple external defects (including those with NTD and another major external birth defects that is not the sequence of a defect such as cleft lip with or without cleft palate). The rates of anencephalus, encephalocele, high- and low-level spina bifida (SB) in males and females and their sex ratios were calculated, adjusted for urban and rural areas, season, category and birth outcome by sex and sites of lesions (high vs. low). RESULTS: Totally, 784 NTD cases were identified from 326 874 recorded births (including live births, stillbirths and fetal deaths with a gestation age of at least 20 weeks). The prevalence rates of anencephalus (1.30 per 1 000 female births) and high-level SB (3.99) in females were higher than those (0.66 and 1.66 per 1 000 male births) in males in the high-prevalence northern regions; with adjusted prevalence rates of females 1.8 - 2.1 times greater than those of males. In the low-prevalence southern regions, the prevalence of high- (0.32 per 1 000 female births) and low-level SB (0.21) in female were higher than those in males, with high- and low-level SB rate of 0.10 and 0.09 per 1 000 male births), with adjusted rates for females of 1.3 - 1.6 times higher than in males. Isolated NTD accounted for more than 80% of all NTD cases, and the prevalence of isolated NTD in females (2.57) was higher than that in males (1.40). CONCLUSIONS: The sex differences in NTD existed between north and south, in accordance with the phenotype of NTD. It suggested that proportion of high level SB and anencephalus in females could increase as the prevalence of NTD going up, anencephaly, high- and low-level SB had the different genetic and environmental background.