Netherlands 1998.
Methods | Randomisation: random numbers in blocks of 10. Stratified by centre. Allocation concealment: sealed, numbered, opaque envelopes. Follow up: no loss to follow up (A). Blinding: participants not blinded. Caregiver blinded only to urinary sodium concentration. Blinding of outcome assessment not reported. | |
Participants | 361 women booked for midwifery care, nulliparous, DBP < 90 mmHg at booking visit before 20 weeks. Randomised if DBP > 85 x 2 in subsequent visit, or weight gain > 1 kg/week for 3 consecutive weeks, or excess oedema. Excluded if planning to leave the city or risk factors for PIH. | |
Interventions | Low: sodium‐restricted diet, aimed at less than 50 mmol/day. Written dietary instructions given by midwife. Normal: asked not to change eating habits. | |
Outcomes | Woman: highest DBP, PE (HT (not defined) with significant proteinuria (not defined)), eclampsia, hospital referrals and admissions for HT, time to delivery, abruption, mode of delivery. Baby: death, gestation at delivery (mean), birthweight, Apgar at 5 minutes, NICU admission. | |
Notes | Multicentre study: 9 centres. Setting: midwifery practices and hospital clinic. Mean urinary sodium after randomisation 84 mmol/day in low sodium group, 124 mmol/day for normal diet. | |
Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Allocation concealment? | Low risk | A ‐ Adequate |
DBP: diastolic blood pressure GH: gestational hypertension HT: hypertension hr: hour NICU: neonatal intensive care unit PE: pre‐eclampsia PIH: pregnancy induced hypertension SGA: small‐for‐gestational age