Internal Fetal Monitoring

Internal fetal monitoring (IFM) is sometimes used when a pattern of non-reassuring fetal heart tones has been detected during labor.  This can include a non-reactive pattern in which the baby's heart rate drops during contractions, which is a normal occurrence and is expected, but then fail to return to a normal rate after the contraction. This type of pattern can indicate fetal distress such as from oxygen deprivation or general stress from the labor process. It can also indicate potential placental problems or a compressed umbilical cord.

During a contraction, the oxygen supply to the baby decreases and then resumes to normal levels once the contraction subsides.  When pitocin is using to augment labor, currently in 80% of hospital births in the US, it can cause fetal distress in that pitocin-induced contractions are unnaturally longer and stronger with shorter rest periods between them than the spontaneous uterine contractions produced by a woman's body.  In this case, the wisest course of action is to either stop or lower the dose of pitocin and then re-assess the fetal heart tones rather than opting for an invasive procedure first such as the use of internal fetal monitoring.

While internal fetal monitoring is the most accurate assessment of true fetal condition, it is also extremely invasive.  It  uses an electrode that is screwed directly into the baby's scalp to measure the heart rate.  A pressure monitor to measure the relative strength of contractions often accompanies it.  The wires will be taped to the mother's leg so they do not get pulled out when shifting position.

The largest disadvantage of this method is that the bag of waters must be ruptured, i.e. an amniotomy must be performed, in order to place the internal fetal monitor.  This increases the risk of infection, limits mobility which can in turn prolong labor, increases pressure on the baby's head, increases the chances of dilating with an anterior cervical lip, and is painful for the baby.

In addition, once the bag of waters is ruptured, either naturally or artificially, mothers will be put "on the clock" to deliver within a certain time frame in a hospital birth.  Depending on location, this can range from 12-24 hours.  Some care providers even insist on a 6 hour time limit.  This is due to the fact that once the waters break, the chance of infection increases dramatically, especially if repeated cervical checks are performed.

However, research has shown that the risks do not increase until after 24 hours have passed.  However, most providers and hospital policies will be pressuring for a cesarean section much before this time limit has expired.   The risk of infection can be limited by refusing all cervical checks.  They are the easiest way to transfer infection to the mother and provide little useful information and are not required routinely in any labour.

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Page Last Modified by Catherine Beier, MS, CBE