Neurohypophysial hormones are thought to be involved in alterations in fluid balance during pregnancy and delivery. In the course of normal pregnancy intravascular volume is increased whereas sodium restriction is thought to reduce plasma volume and cardiac output. In the present study, we measured the effect of long-term severe sodium restriction on vasopressin (AVP) and oxytocin (OT) levels during normal pregnancy and after delivery.Fifty-nine healthy nulliparous women were randomized either for a low sodium diet (20 mmol sodium daily) or for a normal diet from week 12 of pregnancy onwards, Circulating plasma levels and urinary excretion of AVP and OT, their neurophysins (Np-AVP and Np-OT) and AVP bound to platelets were determined at regular intervals during pregnancy and after delivery. After com pletion of the study, women on a sodium-restricted diet were compared with control women on a normal diet using repeated measurement ANOVA with adjustment for potentially confounding variables.After randomization, a reduction in urinary sodium excretion of, on average, 40-82% was found. In general, no effect of sodium restriction could be demonstrated on the various parameters (0*53< P < 0*98) with the exception of a significantly lower 24-h urinary AVP excretion by non-smokers with sodium restriction compared with non-smokers having a normal diet (P=0'018). For all parameters, clear changes were found in the course of pregnancy and puerperium (P<0*0001 to P<0'005). Platelet-bound AVP decreased and N p -O T increased during pregnancy. After birth, free plasma AVP, plateletbound AVP, O T, osmolality, sodium and potassium increased, while Np-AVP and N p -O T decreased.Although elevated Np-AVP and N p-O T levels during pregnancy seem to indicate increased release of neuro hypophysial hormones, pregnancy up to 36 weeks of gestation is accompanied by low circulating AVP and O T levels.Long-term severe sodium restriction diminishes urinary AVP excretion in (non-smoking) pregnant women, with out changing circulating levels of AVP and OT, despite the known reduction in circulating volume. The reduced circulating (plat el et-bound) AVP levels during pregnancy, whether or not in combination with severe sodium restriction, support the absence of significant non-osmotic stimulation of AVP during pregnancy.
A 30-year-old nulliparous woman underwent surgery for a ruptured aneurysm of the left vertebral artery in gestational week 27. The fetal heart rate (FHR) was monitored continuously with an abdominal Doppler transducer. Anesthesia was induced with midazolam, fentanyl, and thiopental and maintained with fentanyl, isoflurane, and nitrous oxide 67% in oxygen. Surgery was performed under moderate hypotension (mean arterial pressure +/- 70 mmHg) and moderate hyperventilation (arterial carbon dioxide pressure +/- 33 mmHg). There was a complete disappearance of FHR variability without decelerations or bradycardia. In the night following surgery, the patient was sedated with large parenteral doses of midazolam and fentanyl. Despite this sedation, some FHR variability reappeared within 40 minutes after discontinuation of the inhalation anesthetics. After discontinuation of parenteral midazolam and fentanyl, normal FHR variability returned within 60 minutes. In week 41 of pregnancy, a healthy girl of 4015 gm was born.
Dietary sodium restriction is used in the Neth erlands in the prophylaxis of preeclampsia. To study the effects of long-term sodium restriction on the intake of other nutrients and the outcome of pregnancy, 6 8 healthy nulliparous pregnant women were randomly assigned to either a low-sodium diet (20 mmol/24 h) or an unrestricted diet. The diet was consumed between week 14 of gestation and delivery. The dietary intakes of energy, fat, protein, carbohydrate, sodium, potassium, and calcium were esti mated with the dietary-history technique. A low-sodium diet re duced the intake of protein (by «=15 g/24 h), fat (by 20 g/24 h), and calcium (by 350 mg/24 h) and tended to decrease the energy intake (by ^O.? MJ/24 h). The intakes of carbohydrate and potassium did not differ between the groups. The maternal weight gain was less in the low-sodium group (6.0 ± 3 .7 compared with 11.7 ± 4.7 kg). Mean birth weight was not significantly different (3.2 ± 0.5 compared with 3.4 ± 0.5 kg).Am J Clin Nutv 1995;62:49-57.KEY WORDS Sodium-restricted diet, pregnancy, prophy laxis of preeclampsia, energy intake, fat intake, protein intake, carbohydrate intake, calcium intake, maternal weight gain, birth weight, body fat mass
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