Table 3  Interrelationships between maternal hyponatraemia (≤130 mmol/l) immediately postpartum and the various variables analysed with univariate (left) and multivariate (right) logistic regressions
Parameter  Total  Na ≤130  Na ≤130 (%)  Univariate logistic regression  Multivariate logistic regression*
OR (95% CI)  P value  OR (95% Cl)  P value
Fluid group**
<1000  113  1  0.9  1.00   1.00
1000–2500  87  4  4.6  6.8 (2.9–15.7)   5.2 (2.2–12.7)
>2500  61  16  26.2  46 (8.5–247)  <0.001  27 (4.6–162)  <0.001
Oxytocin
<5 units  221  10  4.5  1.00   1.00
≥5 units  40  11  27.5  8.0 (3.1–21)  <0.001  2.6 (0.9–7.4)  0.072
Epidural
No  172  3  1.7  1.00
Yes  89  18  20.2  14.3 (4.1–50)  <0.001  —  —
Parity
Multipara  148  6  4.1  1.00
Nullipara  113  15  13.3  3.6 (1.4–9.7)  0.011  —  —
Body mass index and age are not shown (P = 0.62 and P = 0.59, respectively, in the univariate analysis and are therefore not included in the multivariate analysis).
*  Parity was deleted from the multivariate analyses with P = 0.86 and epidural with P = 0.12.
**  Fluid groups as defined in Tables 1 and 2. The control group elective caesarean section is not included in the analysis.