Pregnancy with known syndrome of inappropriate antidiuretic hormone.

Syndrome of inappropriate antidiuretic hormone (SIADH) is rarely encountered in pregnancy. We report a case of severe hyponatraemia with idiopathic SIADH. A total of 18 cases of hyponatraemia in pregnancy have been reported; seven fit the criteria of SIADH. Unlike our case, none were diagnosed before pregnancy. Of the cases, 13 were associated with pre-eclampsia. Our patient developed intrauterine growth restriction (IUGR) but did not develop pre-eclampsia.