Monitoring uterine activity during pregnancy and labor provides insights into the body’s processes. A fetal monitor, also known as a tocodynamometer, is a common tool to track these activities and help individuals interpret the output.
Understanding the Fetal Monitor
The external fetal monitor uses a tocodynamometer to detect contractions. It is placed on the maternal abdomen and secured with a belt. It measures subtle changes in the tension of the abdominal wall as the uterus tightens.
When the uterus contracts, it becomes firmer, and this change in pressure is transmitted through the abdominal wall to the tocodynamometer. It converts these mechanical pressure changes into an electrical signal. This signal is displayed as a wave-like pattern on a monitor screen or printed paper, representing uterine activity. The display features a vertical axis for relative intensity or amplitude, and a horizontal axis for time and frequency.
Visualizing Contractions on the Monitor
Contractions appear on the monitor’s uterine activity tracing as distinct wave-like patterns, often described as “hill” or “bell-shaped” curves. These curves begin with a gradual rise, reach a peak, and then gradually return to the baseline. Small contractions are represented by waves with a lower amplitude, appearing shorter in height compared to more intense contractions.
The monitor illustrates the frequency and duration of these uterine events. Frequency is the time from the beginning of one contraction wave to the beginning of the next. Duration is measured from the wave’s ascent to its return to the baseline. The external tocodynamometer provides a measure of relative intensity, reflecting changes in abdominal pressure rather than actual uterine muscle strength.
Differentiating Types of Contractions
The monitor’s tracing helps distinguish between various types of uterine activity, even when individual contractions appear “small.” Braxton Hicks contractions, often referred to as “false labor,” typically present as irregular, non-rhythmical waves on the monitor. These practice contractions have a low amplitude and are short in duration. They may also subside with changes in activity or position.
Early true labor contractions, while sometimes starting with a similar “small” appearance on the monitor, show a progressive pattern. Unlike Braxton Hicks contractions, true labor contractions become more regular, increase in duration, and often grow in amplitude over time. The key indicator on the monitor is this evolving pattern of regularity and increasing intensity, rather than the initial size of an individual contraction. True labor contractions persist despite changes in activity.
Interpreting Monitor Readings and When to Seek Guidance
Small contractions on the fetal monitor are a normal occurrence, particularly if irregular, short in duration, and not showing an increasing pattern of frequency or intensity. These are typical of Braxton Hicks contractions. While the monitor provides objective data, its readings should always be considered alongside how the individual feels and any other physical sensations.
Contact a healthcare provider if contractions become consistently regular and closer together, or if they increase in duration or perceived intensity. Other signs that warrant contacting a provider include the breaking of water or any significant vaginal bleeding. The fetal monitor serves as a tool for assessment, but a complete clinical evaluation by a medical professional is essential for accurate interpretation and guidance.