The objective of this study was to measure maternal total digoxin-like immunoreactive factor levels in singleton pregnancies with or without hypertension and in twin pregnancies. Plasma digoxin-like immunoreactive factor was measured in 113 third-trimester patients: 51 normotensives, 20 preeclamptics, 19 with latent or chronic hypertension, and 23 with twin pregnancies. The concentration of total digoxin-like immunoreactive factor in the twin gestations (1143 +/- 249 pg/mL) was significantly higher than that in either the normotensive pregnancies (890 +/- 161 pg/mL) (P less than .001) or in the hypertensive pregnancies (903 +/- 256 pg/mL) (P less than .01). However, there were no significant differences in digoxin-like immunoreactive factor levels between the normotensive and hypertensive groups. A trend of higher, although not statistically significant, levels of digoxin-like immunoreactive factor was noted in the chronic hypertensive group as compared with the preeclamptic patients (957 +/- 212 versus 852 +/- 288 pg/mL). We therefore conclude that digoxin-like immunoreactive factor does not contribute significantly to the pathogenesis or prediction of preeclampsia. The increased amount of digoxin-like immunoreactive factor in twin pregnancies may reflect a contribution from multifetal origin, or might be a physiologic adaptive mechanism allowing higher cardiac output by a possible cardiotropic effect.