Li Kai, He Xiang-bo, Zhang Le, Li Zhi-wen, Ye Rong-wei, Liu Jian-meng, Zhai Rui-qin, Duan Xian-jin, Ren Ai-guo
Department of Epidemiology and Biostatistics, School of Public Health, Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health, Peking University Health Science Center, Beijing 100191, China.
Zhonghua Liu Xing Bing Xue Za Zhi. 2012 May;33(5):509-12.
To examine the impact of pregnancy termination before 28 weeks of gestation on the overall prevalence of neural tube defects (NTDs).
Data collected during the period of 2004 and 2010 from a birth defects surveillance system in Pingding county and Taigu county of Shanxi province were used. Number of births≥28 weeks of gestation and number of cases with major birth defects among the births were collected. Terminations of pregnancies before 28 weeks of gestation due to prenatal diagnosis were also collected. The total prevalence of neural tube defects, prevalence before 28 weeks of gestation, and prevalence of ≥28 weeks gestation were calculated using the total number of pregnancies of ≥28 weeks of gestation as denominator. The prevalence data were compared to examine the impact of pregnancy termination on the total prevalence. The proportions of pregnancy terminations before 28 weeks of gestation due to prenatal diagnosis of an NTD against the total number of NTD cases were also calculated.
During 2004-2010, 52 366 births were recorded, and 485 NTD cases were ascertained. The overall prevalence of NTDs was 92.6 per 10,000 births, with prevalence of <28 weeks gestation due to pregnancy terminations as 60.9 per 10,000 births, while the prevalence of ≥28 weeks of gestation was 31.7 per 10,000 births. NTD prevalence of ≥28 weeks gestation was 66.0% lower than the total NTD prevalence. In the last two years, the proportion of NTDs ascertained ≥28 weeks gestation accounted for about 40.0% of the total NTD cases.
A birth-defect-surveillance program that covered only pregnancies≥28 weeks of gestation resulted in a severe underestimation of the total birth prevalence of NTDs, especially for anencephaly. We would recommend that the current national birth defects surveillance system should include pregnancy terminations before 28 weeks of gestation and the calculation of total NTD prevalence should also include these cases into the numerator, so as to better estimate true population NTD prevalence, upon which the related public health policy is based.
探讨妊娠28周前终止妊娠对神经管缺陷（NTDs）总体患病率的影响。
使用2004年至2010年期间从山西省平定县和太谷县出生缺陷监测系统收集的数据。收集妊娠≥28周的出生数以及这些出生中严重出生缺陷的病例数。还收集了因产前诊断而在妊娠28周前终止妊娠的情况。以妊娠≥28周的妊娠总数为分母，计算神经管缺陷的总患病率、妊娠28周前的患病率以及妊娠≥28周的患病率。比较患病率数据以研究终止妊娠对总患病率的影响。还计算了因产前诊断NTD而在妊娠28周前终止妊娠的比例占NTD病例总数的比例。
2004 - 2010年期间，记录了52366例出生，确诊485例NTD病例。NTDs的总体患病率为每10000例出生92.6例，因终止妊娠导致的妊娠<28周的患病率为每10000例出生60.9例，而妊娠≥28周的患病率为每10000例出生31.7例。妊娠≥28周的NTD患病率比NTD总患病率低66.0%。在最后两年中，确诊的妊娠≥28周的NTD病例数占NTD病例总数的约40.0%。
仅涵盖妊娠≥28周的出生缺陷监测计划导致对NTDs总出生患病率的严重低估，尤其是无脑儿。我们建议当前的国家出生缺陷监测系统应包括妊娠28周前的终止妊娠情况，并在计算NTD总患病率时将这些病例纳入分子，以便更好地估计真实的人群NTD患病率，相关公共卫生政策即基于此。
