Risk factors of eclampsia other than hypertension: pregnancy-induced antithrombin deficiency and extraordinary weight gain.

OBJECTIVE Recent findings suggest that cerebral edema is a characteristic finding on magnetic resonance imaging in women with eclampsia and that pregnancy-induced antithrombin deficiency (PIATD) may reflect enhanced vascular permeability and may allow the retention of excess water in the interstitial space. Whether PIATD and extraordinary weight gain (EOWG) are risk factors for eclampsia remains to be studied. METHODS The medical records of 11 women with eclampsia among 17,522 deliveries were reviewed retrospectively with respect to changes in the laboratory data and the maternal body weight. PIATD was defined as a perinatal antithrombin activity of ≤65% of the normal activity levels with an antenatal decline and/or a prompt postnatal increase. A large net weight gain during the last two antenatal weeks >97.5th percentile value (>4.01 kg) obtained from 272 control women with neither hypertension nor PIATD was defined as EOWG. Relative risk was obtained on the assumption that the prevalences of PIATD and EOWG were 2.0 and 2.5%, respectively, among 17,511 women who did not develop eclampsia. RESULTS The duration of hypertension until an eclamptic fit was within 7 days in all 11 cases. PIATD and EOWG were observed in 6 (54.5%) and 2 (18.2%) cases, yielding a relative risk (95% confidential interval) of 57.9 (17.7-188.7) and 8.65 (1.87-39.91) for eclampsia among women with PIATD and EOWG, respectively. CONCLUSIONS PIATD and EOWG may be risk factors for eclampsia.