[1] Zhang J, Sun K, Zhang YJ. The rising preterm birth rate in China: a cause for concern. Lancet Global Health, 2021; 9, e1179−80. doi:  10.1016/S2214-109X(21)00337-5
[2] Lee ACC, Katz J, Blencowe H, et al. National and regional estimates of term and preterm babies born small for gestational age in 138 low-income and middle-income countries in 2010. Lancet Global Health, 2013; 1, e26−36. doi:  10.1016/S2214-109X(13)70006-8
[3] Conde-Agudelo A, Rosas-Bermudez A, Castaño F, et al. Effects of birth spacing on maternal, perinatal, infant, and child health: a systematic review of causal mechanisms. Stud Family Plann, 2012; 43, 93−114. doi:  10.1111/j.1728-4465.2012.00308.x
[4] Scholl TO, Johnson WG. Folic acid: influence on the outcome of pregnancy. Am J Clin Nutr, 2000; 71, 1295S−303S. doi:  10.1093/ajcn/71.5.1295s
[5] Bruinse HW, van den Berg H. Changes of some vitamin levels during and after normal pregnancy. Eur J Obst Gyn Reproduct Biol, 1995; 61, 31−7. doi:  10.1016/0028-2243(95)02150-Q
[6] van Eijsden M, Smits LJM, van der Wal MF, et al. Association between short interpregnancy intervals and term birth weight: the role of folate depletion. Am J Clin Nutr, 2008; 88, 147−53. doi:  10.1093/ajcn/88.1.147
[7] Naimi AI, Auger N. Population-wide folic acid fortification and preterm birth: testing the folate depletion hypothesis. Am J Public Health, 2015; 105, 793−5. doi:  10.2105/AJPH.2014.302377
[8] Hu X, Yang Y, Wang L, et al. Interpregnancy interval after healthy live birth and subsequent spontaneous abortion. JAMA Netw Open, 2024; 7, e2417397. doi:  10.1001/jamanetworkopen.2024.17397
[9] Nilsen RM, Mastroiacovo P, Gunnes N, et al. Folic acid supplementation and interpregnancy interval. Paediatr Perinat Epid, 2014; 28, 270−4. doi:  10.1111/ppe.12111
[10] Huang X, Tan HZ, Cai M, et al. Gestational weight gain in Chinese women - results from a retrospective cohort in Changsha, China. BMC Pregnancy Childb, 2018; 18, 185. doi:  10.1186/s12884-018-1833-y
[11] Ray JG. Folic acid food fortification in Canada. Nutr Rev, 2004; 62, S35−9. doi:  10.1111/j.1753-4887.2004.tb00072.x
[12] Mamo H, Dagnaw A, Sharew NT, et al. Prevalence of short interpregnancy interval and its associated factors among pregnant women in Debre Berhan town, Ethiopia. PLoS One, 2021; 16, e0255613. doi:  10.1371/journal.pone.0255613
[13] Zhao YL, Hao L, Zhang L, et al. Plasma folate status and dietary folate intake among Chinese women of childbearing age. Matern Child Nutr, 2009; 5, 104−16. doi:  10.1111/j.1740-8709.2008.00172.x
[14] Ren AG. Prevention of neural tube defects with folic acid: the Chinese experience. World J Clin Pediatr, 2015; 4, 41−4. doi:  10.5409/wjcp.v4.i3.41