Investigating The Association Of Women's Pre-Pregnancy Nutrition And Adverse Pregnancy Outcomes In Rural China

Unhealthy maternal nutrition before pregnancy increases the risk of various adverse pregnancy outcomes.We conducted a nutrition survey to provide baseline data on the pre-pregnant nutritional status of mothers in order to better understand the association between maternal nutrition before pregnancy and adverse outcomes.We did a large,prospective,population-based cohort study.Data was from the National Free Pre-pregnancy Health Examination Project(NFPHEP)in China during 2010-2012.The primary nutrition indicators included body mass index(BMI)and Hemoglobin concentration(Hb).Adverse outcomes included preterm birth(PTB),low-birth-weight(LBW),spontaneous miscarriage(SM),ectopic pregnancy(EP)and stillbirth(SB).Chi-square test for trend was used to compare the prevalence of each BMI or Hb category during 2010-2012.Univariable and multiple logistic regression analyses were performed to assess the association between pre-pregnancy BMI or Hb and various adverse pregnancy outcomes.2,120,131 childbearing women were evaluated.The average BMI decreased from 21.31 to 21.16,while underweight prevalence increased from 10.40%to 14.14%during 2010-2012.An age-stratified subgroup analysis indicated underweight prevalence increased from 13.52%to 17.02%among women aged 21-24 and from 10.72%to 13.71%among 25-to 34-year-old women.Overweight prevalence increased from 9.84%to 10.75%(25-34 years)and from 17.10%to 19.20%(35-49 years).Obesity prevalence increased from 2.17%to 2.42%and from 4%to 4.2%among women aged 25-34 and 35-49 respectively.From 2010 to 2012,the average hemoglobin concentration of women in reproductive age increased from 125.70 g/L to 126.78 g/L,and the anemia prevalence decreased from 13.24%to 10.4%.There was a 21.71%decrease in mild anemia,a 17.89%decrease in moderate-to-severe anemia,and a 9.4%decrease in high hemoglobin concentration.536,098 women with pregnancy outcomes were evaluated in the association of pre-pregnancy BMI and adverse pregnancy outcomes,and 527,386 pregnant women were analyzed in the association of pre-pregnancy hemoglobin concentration and adverse pregnancy outcomes.In the relationship analysis,pre-pregnancy underweight was associated with PTB,LBW and SM;overweight women had an increased risk of LBW;obese women had a higher risk of LBW,SM,EP and SB.Mild anemia before pregnancy was associated with PTB,SM and SB when compared with pre-pregnancy normal hemoglobin concentration.High hemoglobin concentration was associated with PTB and SM.However,moderate to severe anemia was not associated with adverse birth outcomes;mild anemia and high hemoglobin concentration were not associated with LBW.Though the average pre-pregnancy BMI decreased,the prevalence of underweight individuals in a very large population significantly increased.The average pre-pregnancy hemoglobin concentration increased,and the prevalence of anemia individuals significantly decreased in China's rural areas.Pre-pregnancy maternal underweight,overweight and obesity were associated with increased risks for adverse pregnancy outcomes.Pre-pregnancy maternal mild anemia and high hemoglobin concentration were associated with increased risks for adverse pregnancy outcomes.