(Patho)physiological implications of chronic dietary sodium restriction during pregnancy; a longitudinal prospective randomized study.
Study Goal
To study the pathophysiological implications of long-term dietary sodium restriction during pregnancy, comparing a low sodium diet to unrestricted sodium intake.
Results Summary
Sodium restriction led to reduced maternal weight gain, lower circulating volume, higher systemic vascular resistance, and no major effects on blood pressure or birthweight.
Population
42 healthy nulliparous women.
Effective Dosage
20 mmol sodium daily.
Duration
From the 14th week of pregnancy until delivery.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
low sodium diet (20 mmol sodium daily) | decrease | total maternal weight gain during pregnancy | healthy nulliparous women | - | significantly lower | #1 |
low sodium diet (20 mmol sodium daily) | decrease | dietary energy intake during pregnancy | healthy nulliparous women | - | significantly lower | #2 |
low sodium diet (20 mmol sodium daily) | decrease | weight at 1 week postpartum | healthy nulliparous women | - | significantly lower | #3 |
low sodium diet (20 mmol sodium daily) | decrease | weight at 6 weeks postpartum | healthy nulliparous women | - | significantly lower | #4 |
low sodium diet (20 mmol sodium daily) | no change | blood pressure during pregnancy | healthy nulliparous women | - | did not show major differences | #5 |
low sodium diet (20 mmol sodium daily) | decrease | stroke volume during pregnancy | healthy nulliparous women | - | significantly lower | #6 |
low sodium diet (20 mmol sodium daily) | decrease | cardiac output during pregnancy | healthy nulliparous women | - | significantly lower | #7 |
low sodium diet (20 mmol sodium daily) | increase | systemic vascular resistance during pregnancy | healthy nulliparous women | - | significantly higher | #8 |
low sodium diet (20 mmol sodium daily) | decrease | haematocrit values during pregnancy | healthy nulliparous women | - | tended to be lower | #9 |
low sodium diet (20 mmol sodium daily) | decrease | haematocrit values at 1 week postpartum | healthy nulliparous women | - | significantly lower | #10 |
low sodium diet (20 mmol sodium daily) | decrease | haematocrit values at 6 weeks postpartum | healthy nulliparous women | - | significantly lower | #11 |
low sodium diet (20 mmol sodium daily) | no change | placental weight | healthy nulliparous women | - | not significantly different | #12 |
low sodium diet (20 mmol sodium daily) | no change | birthweight | healthy nulliparous women | - | not significantly different | #13 |
OBJECTIVE: To study the possible pathophysiological implications of long continued dietary sodium restriction in pregnancy. DESIGN: Longitudinal prospective randomized study of the effects of a low sodium diet compared with unrestricted sodium intake in pregnancy. SETTING: Academic Department of Obstetrics and Gynaecology at Sint Radboud Hospital, Nijmegen, The Netherlands. SUBJECTS: 42 healthy nulliparous women. INTERVENTION: A low sodium diet (20 mmol sodium daily) started in the 14th week of pregnancy and stopped after delivery. MAIN OUTCOME MEASURES: Maternal weight gain, food intake, blood pressure, cardiac output, systemic vascular resistance, haematocrit and birthweight. RESULTS: Total maternal weight gain and dietary energy intake during pregnancy and weight at 1 and 6 weeks postpartum were significantly lower in the low sodium group. Blood pressure during pregnancy did not show major differences. Stroke volume and cardiac output during pregnancy were significantly lower in the low sodium group whereas systemic vascular resistance was significantly higher. Haematocrit values in the low sodium group tended to be lower during pregnancy, but were significantly lower at 1 and 6 weeks postpartum than in the unrestricted group. Placental and birthweights were not significantly different between the two groups. CONCLUSIONS: Chronic dietary sodium restriction during pregnancy is characterized by a diminished body fat accumulation and a reduction in circulating volume, due to a decrease in both plasma and red cell volume, in combination with a high systemic vascular resistance without major effects on blood pressure and birthweight.