Aim: Study of the blood serum content of pro-inflammatory cytokines (interleukin-6 (IL-6), soluble receptor of IL-6, interleukin-8 (IL-8), leptin, lactoferrin) during pregnancy and their role in the development of the threat of premature birth and preeclampsia (PE). Materials and methods. 180 pregnant women were examined, which were divided into 3 groups: Group 1 — 84 patients with threatened preterm labor, group 2 — 48 pregnant women with preeclampsia. Group 3 included 48 pregnant women with a normal pregnancy in the third trimester. Serum levels of IL-6, soluble receptor IL-6, IL-8, leptin, lactoferrin were determined using enzyme-linked immunosorbent assay method. Results. It was demonstrated in patients with preeclampsia, the level of IL-6 was increased, and in cases of threatened premature labor it remained at the same level; in women with threatened premature labor, level of the soluble IL-6 receptor was lowered, while in the preeclampsia patients, there was only a tendency to its decrease. The level of lactoferrin was increased in women with threatened premature labor, and it was increased in patients with preeclampsia significantly more. The level of leptin in women with threatened premature labor was elevated; in patients with preeclampsia, this index exceeded its value in the control group by 3 times. The level of IL-8 in women with threatened premature labor was elevated and was even higher in preeclampsia patients. It was established that «sterile» inflammation in PE has a more pronounced systemic nature — there are higher levels of pro-inflammatory cytokines. In cases of threatened premature labor, an increase in the concentration of leptin may be associated both with hypoxia in the myometrium and with the hypoxic inflammatory reaction caused by uterus contraction. Conclusion. Based on the results obtained, we conclude that lactoferrin and the classic indicators of “sterile” inflammation — pro-inflammatory cytokines, as well as the energy regulator leptin, are involved in the pathogenesis of the development of preeclampsia and the threatened premature labor