Longitudinal Measurement of Cytokines in Pre-eclamptic and Normotensive Pregnancies

Objective: To evaluate differences in plasma cytokine levels longitudinally in pre-eclamptic and normotensive pregnancies. An increased inflammatory response has long been associated with pre-eclampsia, both early and late in the pre-eclamptic pregnancy.

Design: Blood samples were collected longitudinally during pregnancy from a cohort of 1 631 pregnant women. Thirty-two women with pre-eclampsia and 67 normotensive pregnant women were identified from the cohort.

Setting: A Danish regional hospital.

Samples: Samples were collected from the 18th week of pregnancy until delivery and divided into the following four gestational intervals: <25th week, 26th-29th week, 30th-35th week and >36th week.

Methods: Simultaneous measurement of all nine cytokines was done using a capture bead system.

Main Outcome Measures: Plasma levels of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor-α, interferon-γ and granulocyte macrophage colony-stimulating factor during pre-eclamptic and normotensive pregnancies.

Results: Pre-eclampsia was associated with increased tumor necrosis factor-α between the 26th and 29th week (p=0.0421) and increased IL-6 after the 36th week (p=0.0044). The other cytokines measured were comparable in the two groups.

Conclusions: This large prospective collection of blood samples was undertaken to determine inflammatory status during pre-eclamptic and normotensive pregnancies. Our results support a tendency towards increased inflammation in pre-eclampsia, but the measured cytokines are not eligible for prediction, monitoring or diagnosing pre-eclampsia.