Morris J K, Wald N J
Department of Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, St Bartholomew's and the Royal London School of Medicine and Dentistry, UK.
J Med Screen. 1999;6(4):182-5. doi: 10.1136/jms.6.4.182.
In England and Wales there has been a large decline in the birth prevalence of neural tube defects (NTDs) from the early 1970s (reported rates of about 3.2 per 1000 births) to the present (0.1 per 1000 births in 1997). The reported number of terminations of NTD pregnancies increased from 0.02 per 1000 in 1970 to 0.66 per 1000 in 1997, much too small an increase to explain the decline in NTD births. Some underreporting of NTD terminations is recognised. We estimated its extent using 1976-80 data on reported central nervous system (CNS) defect terminations and NTD births in an analysis in which the true total number of NTD pregnancies during this short period was assumed to have either remained constant or else to have been changing by a constant amount per year. The estimate was that 56% of NTD terminations were not reported as such and this fitted the data well. In 1997 the estimated birth prevalence of NTDs was 0.14 per 1000 births, a fall of 96% since 1970. This 96% was apportioned as 40% due to antenatal screening and termination of pregnancy and 56% due to a decline in incidence. Over the period 1970-97 there was an increase in dietary folate, and this will have at least in part caused the decline in incidence of NTDs.
在英格兰和威尔士，神经管缺陷（NTDs）的出生患病率自20世纪70年代初（报告的发生率约为每1000例出生3.2例）至目前（1997年为每1000例出生0.1例）已大幅下降。报告的NTD妊娠终止数量从1970年的每1000例0.02例增至1997年的每1000例0.66例，增幅过小，无法解释NTD出生数的下降。人们认识到NTD终止妊娠存在一些漏报情况。我们利用1976 - 1980年报告的中枢神经系统（CNS）缺陷终止妊娠和NTD出生数据来估计漏报程度，在该分析中，假设这一短时期内NTD妊娠的实际总数要么保持不变，要么每年以固定数量变化。估计有56%的NTD终止妊娠未如此报告，这与数据拟合良好。1997年，NTD的估计出生患病率为每1000例出生0.14例，自1970年以来下降了96%。这96%中，40%归因于产前筛查和妊娠终止，56%归因于发病率下降。在1970 - 1997年期间，膳食叶酸摄入量有所增加，这至少在一定程度上导致了NTD发病率的下降。
