The recurrence risk of neural tube defects (NTDs) in a population with high prevalence of NTDs in northern China
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Jufen Liu1,2, Zhiwen Li1,2, Nicholas D.E. Greene3, Hongtian Li1,2 and Aiguo Ren1,2
1Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health and Family Planning Commission of the People’s Republic of China, Peking University, Beijing, P. R. China
2Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing, P. R. China
3UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
Zhiwen Li, email: [email protected]
Keywords: recurrence, neural tube defects, folic acid, supplementation, China
Abbreviations: NTDs: neural tube defects, FA: folic acid
Received: May 24, 2017 Accepted: July 13, 2017 Published: August 03, 2017
Background: Although a number of studies have reported the recurrence risk of NTDs in developed countries, there is little data on the rate of recurrence of NTDs in northern China, a region of high prevalence of NTDs.
Methods: Based on the population-based birth defects surveillance system of five counties, we identified women who had an NTD affected pregnancy from 2004-2015 and a retrospective survey was conducted. The rate of recurrence of NTDs was calculated by the number of recurrent NTDs divided by the first NTDs. Maternal age, body mass index (BMI), gestational weeks, education, and occupation were collected. Information on folic acid (FA) supplements, time and dosage were also recorded.
Results: Among 851 women who had a previous NTD-affected pregnancy, there were 578 subsequent pregnancies, with 10 recurrent NTDs, a 1.7% recurrence rate. The recurrence rate was 1.5% and 2.6% for those taking FA supplements and without FA supplementation respectively. Women with recurrent NTDs had higher BMI before pregnancy compared to those who had a second pregnancy without NTDs. Among the recurrent NTDs, the majority were spina bifida.
Conclusions: The recurrence rate of NTDs was approximately five times higher than the overall prevalence in the same region of northern China. Risk of recurrence appeared lower among women who took FA supplements. These findings are consistent with the reduction in NTD frequency in the population since introduction of the nationwide FA supplement program. Data on recurrence rates in northern China will inform power calculations for future intervention studies.
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