Once in the hospital, there is a tendency for the beeping of the monitor to become everyone’s focal point. The family does not even need to be told that interpreting fetal monitoring strips is a tricky business, and best left to the professionals. However, you are an informed health care consumer, and you know that misinterpretation of these wiggly lines has led many to conclude that fetal monitoring is ineffective at best, and can often lead to increased cesarean rates. You may also know that, since 2008, a new effort is in place to tighten up definitions, make training more rigorous, and standardize management of abnormal readings. Call me a rebel, but I love to empower patients as full partners in their care. Understanding what all the fuss is about will enable you to be able to discuss the finer points of your baby’s status.
So here is a brief guide for parents, doulas, and other curious minds, on the not-too-mysterious reading of strips.
A good strip, termed “Category I,” reassures us that baby is neurologically functioning, and not currently deprived of oxygen. This strip has 3 characteristics:
- The heart rate is between 110 and 160 beats per minute
- The heart rate line on the graph paper is not flat, but has some wiggle. This is called “variability” and shows that the baby’s opposing sympathetic and parasympathetic nervous systems are both working and in balance.
- There are no significant dips down (“decels”) in the heart rate. The only sort of decels that are okay are those seen at the very end of the birth, when the head is getting a good squeeze by the descent into the pelvic bones. These are called “earlies.”
A bad strip, termed “Category III,” which means a cesarean section needs to be done if this doesn’t resolve pretty quickly, shows these characteristics:
- The heart rate line has a visually apparent, smooth, sine wave-like undulating cycle of 3-5 minutes for 20 minutes or more. This is the dreaded “sinusoidal” pattern, which happens when baby is extremely anemic. Short periods of this pattern can occur after a mom is given Stadol, a common pain medication. It can also happen briefly if baby is sucking her thumb, which is not a problem. This is why we wait for 20 minutes to see if it resolves. OR
- The heart rate line is flat as can be, without any detectable variability, AND
- There are subtle dips that start after the peak of more than half of the contractions (“recurrent lates”) OR
- There are deep decels happening with more than half of the contractions (“recurrent variables”) OR
- The heart rate is less than 110 and staying that way
Category II, as you can guess, is anything in between. Over 80% of babies will have fetal heart rate patterns that are in this category for at least part of their labor. As many as 1/3 of babies have a cord wrapped around a body part, which is compressed by contractions. Most of them do just fine. Here are things we do when the Category II changes happen:
- Change mother’s position
- Give IV fluids
- Give mom oxygen by facemask
- Do an amnioinfusion, which is pushing sterile fluid into the uterus
- Use medications to stop contractions, or stop giving Pitocin, which causes them
- Have mom push only every other or every third contraction
- Give mom medication to raise her blood pressure if it has been lowered by an epidural
- Check to be sure the umbilical cord is not coming out before baby
Hopefully, your trust in your health care providers will be complete and unwavering. When you look at the fetal monitoring strip, and your interpretation agrees with theirs, it will reassure you that they know what they are doing. This brief guide took you a few minutes to read. Your health care providers will have spent many, many hours being trained and tested on interpreting these strips. And you certainly don’t want it documented in the legal record that you delayed care by arguing with them. But at least you have some familiarity with the terms. You can participate in the discussion of the baby’s condition. This is your baby. You will handle the outcome of the day’s events. Feel the power!