Summary

Background:

Listening to patients and obtaining a thorough history are fundamental in clinical practice. Some pregnant women, particularly in late or preterm gestation, report regular, painful uterine contractions that may not correspond to true labor. In some cases, patients admitted to feigning contractions using the Valsalva maneuver to gain secondary benefits. Misdiagnosing such cases may lead to unnecessary interventions, including iatrogenic prematurity.

Objectives:

To explore the phenomenon of pseudo-uterine contractions and assess whether maternal heart rate (HR) can help differentiate them from true contractions.

Methods:

We performed a prospective case-crossover study, which included 30 pregnant women in their third trimester who presented to Rambam Health Care Campus. Participants underwent 20 minutes of standard external monitoring followed by 10 minutes of repeated Valsalva maneuvers (every 2 minutes). Maternal and fetal HRs were recorded and compared during baseline, pseudo-, and true contractions.

Results:

During pseudo-contractions, maternal HR decreased by approximately 10 bpm (P < 0.001), while fetal HR increased by 8 bpm (P < 0.001). In contrast, true contractions resulted in a maternal HR increase of 15 bpm (P < 0.001) and a fetal HR rise of 12 bpm (P < 0.001).

Conclusions:

Maternal HR patterns differ significantly between true and false contractions. A decline in maternal HR during contractions may indicate Valsalva-induced pseudo-contractions, while an increase suggests true labor. This simple observation could aid in preventing unnecessary interventions in suspected cases.