Uterine contraction frequency in the last hour of labor: how many contractions are too many?

Objective: Increased frequency of uterine contractions is a component in the cluster of causal conditions that can lead to fetal hypoxia and acidosis and increase the risk for neonatal neurologic injury. For most international obstetrical societies, 5 contractions per 10 min averaged over 30 min is considered as the upper limit of normal uterine activity. We hypothesize that it might be safer to adopt an upper limit of 4 contractions per 10 min.

Bacterially induced preterm labor in the mouse does not require maternal interleukin-1 signaling.

Objective: We tested the hypothesis that intrauterine bacterial inoculation induces labor via expression of the inflammatory cytokine interleukin-1 (IL-1) in a murine model.

Study Design: Pregnant mice on day 14.5 of a 19-20 day gestation were inoculated with killed Escherichia coli or sterile media into either (a) the right uterine horn, (b) the right uterine horn following its surgical isolation from the contralateral horn and cervix, or (c) the kidney.