Objective: To investigate maternal cardiac output in the first trimester as a predictor of preeclampsia and delivery of small for gestational age (SGA) infants.
Methods: In women attending for routine care between 11(+0) and 13(+6) weeks of gestation, we recorded maternal variables and measured cardiac output by echocardiography. We compared cardiac output in those that developed preeclampsia (n=83), pregnancy-induced hypertension (PIH) (n=87), or SGA (n=532) with those unaffected by preeclampsia, PIH, or SGA (n=3,591). Regression analysis was used to first determine which of the factors among the maternal variables were significant predictors of cardiac output in the unaffected group and, secondly, to predict each complication by a combination of maternal variables and cardiac output.
Results: In the unaffected group, cardiac output increased with gestation and maternal weight and decreased with maternal age. Cardiac output was higher in parous women, in cigarette smokers, in those taking antihypertensive or beta-mimetic medications, and in those conceiving after in vitro fertilization, and lower in women of Afro-Caribbean origin. Compared with the unaffected group, cardiac output was significantly higher in the preeclampsia and PIH groups and lower in the SGA group. In screening by cardiac output and maternal variables, for a 10% false-positive rate, the detection rates were 43.4% for all preeclampsia, 52% for preeclampsia without SGA, 23.3% for PIH, and 23.9% for SGA.
Conclusion: In pregnancies complicated by preeclampsia, PIH, and SGA, alterations in maternal cardiac output predate the clinical onset of the disorders by several months. Maternal cardiac output in the first trimester is increased in women who develop preeclampsia and decreased in women who deliver SGA infants.
Level of evidence: II.