Impact of preconception sodium intake on hypertensive disorders of pregnancy: The Japan Environment and Children's study

Abstract

Objectives: Determining the appropriate preconception care to reduce the occurrence of hypertensive disorders of pregnancy (HDP) remains a challenge in modern obstetrics. We aimed to examine the association between pre-pregnancy sodium (Na) intake and the development of HDP in normotensive women.

Study design: From the Japan Environment and Children's study (JECS) database, we identified 85,152 normotensive Japanese women who were recruited to the JECS between January 2011 and March 2014. Participants were categorized into five groups according to pre-pregnancy Na intake quintiles (Q1 and Q5 were the lowest and highest Na intake groups, respectively).

Main outcome measures: Multiple logistic regressions were performed to identify the effect of pre-pregnancy Na intake on HDP, early-onset (<34 weeks) HDP, late-onset (34 ≥ weeks) HDP, and HDP with/without small for gestational age (SGA).

Results: Using Q3 (the middle Na intake group) as the reference, multiple logistic regression showed that both the lowest (Q1) and highest (Q5) Na intake groups had an increased risk of HDP with SGA [adjusted odds ratio (aOR): 1.50, 95% confidence interval (CI): 1.02-2.21 and aOR: 1.52, 95% CI: 1.03-2.24, respectively].

Conclusions: Both lower and higher Na intake before pregnancy increases the risk of HDP with SGA in normotensive Japanese women. This finding may indicate new recommendations for Na intake before pregnancy to prevent HDP.

Keywords: Cohort studies; Dietary sodium chloride; Preconception care; Pregnancy-induced hypertension; Sodium.