Qin Xu1,2, Ying Yang2,3, Fangchao Liu4, Long Wang5, Qiaomei Wang6, Haiping Shen6, Zongyu Xu6, Yiping Zhang6, Donghai Yan6, Yuan He2,3, Ya Zhang2,3, Hongguang Zhang2,3, Zuoqi Peng2,3, Xu Ma2,3,4. 1. National Research Institute for Health and Family Planning, No. 12, Dahuisi Road, Haidian District, Beijing100081, China. 2. Graduate School of Peking Union Medical College, Beijing, 9 Dongdansantiao, Dongcheng District, Beijing100730, China. 3. National Human Genetic Resources Center, No. 12, Dahuisi Road, Haidian District, Beijing100081, China. 4. Department of Epidemiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing100037, China. 5. Institute of Epidemiology and Statistics, School of Public Health, Lanzhou University, Lanzhou730000, China. 6. Department of Maternal and Child Health, National Health Commission of the People's Republic of China, Beijing, China.
Abstract
OBJECTIVE: Evidence on the relationship between maternal Hb concentration and spontaneous abortion (SA) risk is limited and conflicting. The purpose of the study was to evaluate whether maternal preconception anaemia or high Hb concentration is associated with risk of SA. DESIGN: A population-based cohort study established between 2013 and 2017. SETTINGS: Local maternal and child care service centres in each county. PARTICIPANTS: In total, 3 971 428 women aged 20-49 years, who participated in National Free Pre-Pregnancy Checkups Project from 2013 to 2016 and successfully got pregnant before 2017 in rural China. RESULTS: A total of 101 700 (2·56 %) women were recorded having SA, with highest SA rate in women with severe anaemia (4·58 %). Compared with women with Hb of 110-149 g/l, the multivariable-adjusted OR for SA was 1·52 (95 % CI: 1·25, 1·86) for women with Hb < 70 g/l, 0·92 (0·84, 1·01) for 70-99 g/l, 0·80 (0·77, 0·83) for 100-109 g/l, 1·11 (1·08, 1·15) for 150-159 g/l, 1·12 (1·04, 1·20) for 160-169 g/l and 1·02 (0·93, 1·12) for ≥ 170 g/l, respectively. An approximate U-shaped curve for the risk of SA with Hb concentrations was observed when Hb concentrations less than 145 g/l, above which the association plateaued (Pnon-linear < 0·001). CONCLUSIONS: Severe anaemia and high Hb concentration before pregnancy were associated with an increased risk of SA. Women with mild anaemia prior to pregnancy had lower risk of SA. Underlying mechanisms need to be further studied.
OBJECTIVE: Evidence on the relationship between maternal Hb concentration and spontaneous abortion (SA) risk is limited and conflicting. The purpose of the study was to evaluate whether maternal preconception anaemia or high Hb concentration is associated with risk of SA. DESIGN: A population-based cohort study established between 2013 and 2017. SETTINGS: Local maternal and child care service centres in each county. PARTICIPANTS: In total, 3 971 428 women aged 20-49 years, who participated in National Free Pre-Pregnancy Checkups Project from 2013 to 2016 and successfully got pregnant before 2017 in rural China. RESULTS: A total of 101 700 (2·56 %) women were recorded having SA, with highest SA rate in women with severe anaemia (4·58 %). Compared with women with Hb of 110-149 g/l, the multivariable-adjusted OR for SA was 1·52 (95 % CI: 1·25, 1·86) for women with Hb < 70 g/l, 0·92 (0·84, 1·01) for 70-99 g/l, 0·80 (0·77, 0·83) for 100-109 g/l, 1·11 (1·08, 1·15) for 150-159 g/l, 1·12 (1·04, 1·20) for 160-169 g/l and 1·02 (0·93, 1·12) for ≥ 170 g/l, respectively. An approximate U-shaped curve for the risk of SA with Hb concentrations was observed when Hb concentrations less than 145 g/l, above which the association plateaued (Pnon-linear < 0·001). CONCLUSIONS: Severe anaemia and high Hb concentration before pregnancy were associated with an increased risk of SA. Women with mild anaemia prior to pregnancy had lower risk of SA. Underlying mechanisms need to be further studied.
Entities:
Keywords:
Anaemia; Cohort study; High Hb; Pre-pregnancy; Spontaneous abortion