Akinkugbe A, Adewoye H O, Eneli A C
Br J Obstet Gynaecol. 1977 Nov;84(11):855-8. doi: 10.1111/j.1471-0528.1977.tb12507.x.
Serum electrolytes, creatinine, urea and urine osmolality were estimated in 25 healthy pregnant women at term, 25 women in early normal labour, and 25 healthy parturients in prolonged labour. A statistically significant fall in serum potassium was found in early labour with a further significant fall in prolonged labour. Bicarbonate changes followed the same pattern of a progressive fall. Sodium fell slowly, reaching significant levels only in prolonged labour and chloride fell even more slowly. There was a conspicuous or significant rise in serum urea with a smaller, not significant rise in creatinine. The rapid insensible loss of water in tropical areas was reflected in the rise in serum urea while homeostatic mechanisms maintained a slower fall in sodium and chloride by renal conservation.
