A contraction monitor, or tocodynamometer, is a device used by doctors for accurately monitoring uterine activities. It is used along with electronic fetal monitoring, or cardiotocograph, for recording the fetal heart rate. In some women, the monitor will register a contraction, but they may not feel them at all. The event is entirely normal, and a contraction on the monitor does not always mean that she is going into labor. It may be just a normal physiological uterine activity that softens the cervix and prepare it for delivery.
Uterine contraction is normal and occurs throughout the pregnancy. Some contractions are mild and subtle, and moms are unaware that it is even happening.
These are the kind that is not strong enough to dilate the cervix. Some contractions are painful but are just Braxton Hicks or false contractions.
Monitoring the contraction is important to address the possibility of preterm labor. That is why later in your pregnancy, your doctor will perform a routine cardiotocography as early as the 28th week.
It will screen the fetal heart activity and the muscles of the uterus to keep track of its simultaneous contractions.
Not feeling the contractions
Did you know that a non-pregnant uterus also generates strong uterine contraction?
That’s because the uterus is a muscle that works to expel its contents – including the baby when pregnant. However, the body has a unique mechanism that prevents the expulsion of the fetus in a majority of pregnant mothers.
In pregnancy, the uterus expands excessively, and the uterine tone rises. The contractions then begin to vary in intensity, frequency, strength, duration, and even in shape. Thus, the preparatory contractions also vary in every mother’s perception.
Contractions go unnoticed when it is weak, small, and occur in a short duration. These low-intensity contractions happen during the early stages of the pregnancy.
Secondly, moms may experience a Braxton Hicks contraction that may be mild but frequent. However, Braxton Hicks can either be subtle or too strong that mothers believe they are already experiencing true labor.
True labor happens only when the contractions are strong, timely, and frequent. So even when the monitor shows contraction but you’re not feeling any pain, you are unlikely to go into labor.
Some women may not even feel them until late in the 40th week of their pregnancies.
How uterine contractions are monitored
Uterine contraction is necessary for doctors to assess the changes in the cervix. Before the advent of electronic gauges, it is monitored using manual palpation.
This traditional method can identify the frequency and duration of contraction. But, it cannot accurately quantify its intensity which is rated only as mild, moderate, or strong.
Mechanical devices such as a tocodynamometer fill this gap by accurately measuring the intensity, duration, and frequency. It helps the doctors assess uterine activity and monitor the progress of labor.
The average fetal heart rate is ideally between 110 to 160 beats per minute. This heart rate can change as the fetus responds to the changes in the uterus.
When the pattern on the monitor shows an irregular pattern, probably, the baby is not getting enough oxygen. It may also indicate other underlying fetal problems.
There are two types of monitoring the fetus and the contractions: external and internal monitoring.
External monitoring is similar to the traditional manual palpation method. It tells about the frequency of the contraction and less accurately about its duration and intensity. This method is a part of the initial assessment done to a mother upon arrival at the birthing facility.
In external fetal monitoring, a small ultrasound disc is placed on the mother’s abdomen, and another near the fetal heart. This pressure-sensitive device will monitor the baby’s heart rate and the mom’s contraction.
It is a non-invasive procedure and the standard method used for monitoring uterine contraction.
In some cases, the doctor may send you home, and you can do the external fetal monitoring yourself. When the monitor shows changes, you can call your doctor to update the status of your contractions.
Internal fetal monitoring is used only if the doctor deems that the baby needs close monitoring.
In this method, a thin catheter is inserted into the uterus. A small electrode is also attached to the fetal scalp to monitor his heartbeat.
This method can accurately rate the duration, frequency, and intensity of the contraction, as well as the fetal well-being. The device is too sensitive that it may show a diminishing graph of contractions even before your pain subside.
Internal monitoring may cause bruising of the baby’s scalp and other body parts. It is also not intended for women with herpes lesions to prevent transferring the infection to the baby.
When is fetal heart monitoring used?
Fetal heart monitoring is used in all pregnancies to assess fetal well-being and identify pregnancy and labor problems.
What are the signs of labor?
True labor happens when it is accompanied by water breaking, bloody discharge, lower back pain, and strong and regular contractions.
Some women may experience flu-like symptoms and nesting tendency a few days before the delivery.
Will fetal heart monitoring limit my mobility?
External fetal monitoring is greatly affected by position. You may be encouraged to lie in a supine position to obtain the best tracing. Internal monitoring does not limit your mobility, but a catheter to the uterus can feel a bit uncomfortable.
What happens if I experience contractions too early in pregnancy?
If you have painful contractions but way too early in pregnancy, your doctor may need close monitoring. You may either be admitted to a birthing facility or prescribed tocolytic and vasodilator medicine.
Electronic devices like the tocodynamometer provide relative and graphical data of fetal and uterine conditions.
When the monitor shows contractions, but the pregnant woman does not feel pain, it is unlikely that she is already going into labor. There is nothing to worry about subtle contractions either. She may be advised to go home and keep track of her contractions.
True labor happens when the contractions get intense, frequent, and accompanied by other signs of labor.