Low serum interleukin-17 is associated with preterm delivery.

Objective: To study maternal serum interleukin-17 (IL-17) during normal pregnancy and evaluate the association with preterm delivery.

Design: Prospective study.

Setting: Aarhus University Hospital, Denmark.

Population: Three cohorts: (a) low-risk cohort of 1,069 women who had serum drawn in weeks 12 and 19, (b) subgroup of the low-risk cohort, consisting of 40 women, who had serum drawn at 12, 19, 26, 33 and 39 weeks of gestation and (c) a symptomatic cohort of 93 women admitted with symptoms of preterm delivery at a gestational age of 24(+ 0) weeks to 33(+ 6) weeks.

Methods: Serum IL-17 determined by an in-house developed multiplex sandwich immunoassay.

Main Outcome Measures: Preterm delivery <37(+0) weeks gestation.

Results: Serum IL-17 did not change during normal pregnancy. At admission to hospital, women with preterm contractions had significantly decreased serum IL-17 as compared with normal pregnancies (median <4 [interquartile ranges, IQR, <4-10 pg/ml] vs. 174 pg/ml [IQR, 92 - 485 pg/ml]); this difference was enhanced and highly significant for women delivering preterm versus term (median <4 [IQR, <4-7.9 pg/ml] vs. median 6.0 [IQR, <4-221 pg/ml]; p-value 0.03). Serum IL-17 was also lower in women with preterm prelabor rupture of membranes. A slightly, but not statistically significant decrease was found in weeks 12 and 19 in low-risk women who subsequently delivered preterm.

Conclusion: Maternal serum IL-17 may be involved in preterm delivery.