Prepregnancy low-plasma volume and predisposition to preeclampsia and fetal growth restriction.

Objective: To estimate whether recurrence risks of preeclampsia, preterm birth, and fetal growth restriction relate to prepregnancy plasma volume.

Methods: We conducted a retrospective cohort study in 580 formerly preeclamptic women and a control group. In all women we measured plasma volume (iodine-human serum albumin indicator dilution method) in the nonpregnant state. One hundred seventy-eight normotensive (formerly preeclamptic) women had a subsequent pregnancy within the study period (1996-2008). Odds ratios (ORs) for recurrent preeclampsia, preterm birth, and small for gestational age (SGA) neonates were estimated, using multivariable logistic regression with adjustment for confounders.

Results: Plasma volumes were lower in women who developed recurrent preeclampsia (1,241±158 mL/m², 17% lower compared with women in the control group) than in women without recurrent preeclampsia (1,335±167 mL/m², 11% lower compared with women in the control group). Logistic regression analysis demonstrated that each 100-mL/m difference in plasma volume was associated with an OR of 0.6 (95% confidence interval [CI] 0.5-0.8) to develop recurrent preeclampsia in subsequent pregnancy. Risk of preterm delivery (before 37 weeks of gestation) depended on preeclampsia in subsequent pregnancy, the adjusted hazard ratio for preterm birth was 0.9 (95% CI 0.7-1.1) for each 100-mL/m² change in plasma volume. Risk of delivering an SGA neonate was independent of recurrent preeclampsia. Each 100-mL/m² change in plasma volume was associated with an adjusted OR of 0.8 (95% CI 0.5-0.9) to deliver an SGA neonate in subsequent pregnancy.

Conclusion: The risk of recurrent preeclampsia and fetal growth restriction in subsequent pregnancy relates inversely and linearly to prepregnancy plasma volume.