In nine women studied serially before conception and through the first trimester, plasma osmolality (Posm) started to decline with the first missed menstrual period, was significantly decreased by the fifth week of pregnancy and was 10 mosmol/kg lower than preconception values by the tenth week, changing little thereafter. Changes in plasma sodium (and its attendant [...]

The metabolic clearance rate (MCR) of arginine vasopressin (AVP) increases fourfold during human pregnancy. To explore whether circulating vasopressinase may play a role in this change, six women underwent a three-tier infusion clearance study, twice, in random order, to determine the MCRs of either AVP or 1-deamino-8-D-AVP (dDAVP, an analogue resistant to degradation by vasopressinase). [...]

Osmoregulation was studied in eight women during late pregnancy and again 8-10 wk postpartum. Base-line plasma osmolality (Posmol) was significantly lower during (280.9 +/- 2.1 mosmol/kg, SD) than after (289.4 +/- 2.1 mosmol/kg) pregnancy yet 24-h urinary volume and plasma arginine vasopressin (PAVP) measured in vasopressinase-inactivated blood was similar in both groups (pregnancy, 1.39 +/- [...]

Serial studies were designed to characterized changes in osmoregulation throughout gestation. Eight women underwent a 2-h infusion of hypertonic saline before conception, during gestational weeks 5-8, 10-12, and 28-33, and then 10-12 wk postpartum. Basal plasma osmolality (Posmol) was already significantly decreased by 5-8 wk (P less than 0.001) and remained 10 mosmol.kg-1 below nonpregnant [...]

An in-hospital prospective, observational cohort study was conducted to assess the effects of type of feeding (exclusively breastfed [EBF] vs partially breastfed [PBF]) on the hydration status of near-term newborns in the first week of life. A total of 205 babies of 35 to 37 weeks of completed gestation were enrolled (82 in the EBF [...]

No abstract available.

This study was conducted in 4 villages in India during the hottest and driest season of the year to determine whether exclusively breast-fed infants need additional water under extremely hot and dry climatic conditions. The ambient temperature was 35-40 degrees C and the relative humidity 10-35%, except during the early morning hours. 63 urine samples [...]

During normal pregnancy total body water increases by 6 to 8 liters, 4 to 6 liters of which are extracellular, of which at least 2 to 3 liters are interstitial. At some stage in pregnancy 8 out of 10 women have demonstrable clinical edema. There is also cumulative retention of about 950 mmol of sodium [...]

OBJECTIVE--To determine whether the fall in plasma osmolality in normal human pregnancy resulted in cellular overhydration. DESIGN--The changes in erythrocyte hydration, potassium and total osmoles in response to a decrease in osmolality in vitro and associated with the fall in plasma osmolality in normal pregnancy were determined. SUBJECTS--Fifty-one women were studied serially during pregnancy and [...]

Earlier results have shown that some infants born by elective Caesarean section start to sweat in a warm environment while others do not, and that sweating can be inhibited by feeding cold glucose. To determine whether these earlier observations, indicating a difference in postnatal temperature adaptation, could be reproduced in vaginally born infants, we measured [...]