Nifedipine in the Management of Preterm Labor

March 11th, 2011

I am always excited to see new medications and treatments for the treatment of preterm labor and management of high risk pregnancy complications. It is my ever present hope that one day there will be no need to put mamas on bed rest.  (Yes, I do hope to put myself out of business in this capacity!) But until that day comes, we need all the help that we can get.

Yet I get a bit nervous when physicians and researchers start shifting and changing medications and using a medication indicated for one ailment for something else-“off label”.  Recently, researchers at the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Perinatology Research Branch, National Institutes of Health, Department of Health and Human Services published a paper stating that Nifedipine, a calcium channel blocker used to lower blood pressure, is a useful tocolytic (anti-contraction) medication for the management of preterm labor. Nifedipine has been used to prevent preterm labor for many years and these researchers sought to determine its efficacy and how it stacked up against other routinely prescribed tocolytics.

Nifedipine is a cardiac medication. I first became acquainted with Nifedipine when I was a newbie physician assistant working with an interventional cardiology group. Many of our patients were on Nifedipine for high blood pressure as well as for aginal chest pain. Nifedipine works by relaxing the smooth muscle of the heart so that it is not pumping so hard. This relaxation allows for more blood to flow through the heart and to the rest of the body, providing more blood, nutrients and oxygen to the body. Because the muscles of the heart are relaxed and there is more oxygen available and delivered to (cardiac) cells, chest pain is relieved.

Nifedipine has a similar mechanism of action on the uterus. Preterm labor is premature contractions of the uterus that can lead to premature delivery. Just as Nifedipine relaxes smooth muscles in the heart, it also relax smooth muscles of the uterus slowing or halting contractions and avoiding preterm labor and delivery. Researchers found that Nifedipine was more efficacious in halting preterm labor contractions than many other tocolytics used, most notably Magnesium Sulfate, a mainstay of preterm labor therapy. Additionally, it was better tolerated by women who used it and women reported having fewer adverse reactions compared to the other medications. So it sounds like Nifedipine is a win win all around.

How will side effects routinely experienced by cardiac patients affect pregnant women? In the cardiac practice, the most common side effects that I saw were headaches, dizziness and flushing. Translating that to pregnant women, who may or not have high blood pressure, are we at risk of “bottoming out” their blood pressure? (Meaning, if they don’t have high blood pressure yet take the medication, will their blood pressures drop too low causing dizziness or fainting?) Women on bed rest, who are already de-conditioned and wobbly, will they be at increased risk for falls?, How about constipation and heartburn, already problematic during pregnancy, yet increased with administration of nifedipine?

Many would readily say that the risk of delivering a premature infant far outweighs the risks of developing so called “nuisance” side effects. However calcium channel blockers, the class to which Nifedipine belongs, are also known to slow heart rate, and are frequently used for patients experiencing atrial (top of the heart) arrhythmias. Now most mamas on bed rest are not experiencing arrhythmias, yet may still experience a slowing in their heart rates. Is Nifedipine transferred to the developing fetus? If so, what effect will it have on fetal heart rate? According to the article, many of these side effects were not experienced by pregnant women taking Nifedipine for preterm labor.

When Nifedipine was given to pregnant women experiencing preterm labor, the women (actually their infants) had significantly reduced incidences of respiratory distress syndrome,  necrotizing enterocolitis, intraventricular hemorrhage, neonatal jaundice, and admission to the neonatal intensive care units. Nifedipine was  also associated with a significant reduction in the risk of delivery within 7 days of initiation of treatment and before 34 weeks’ gestation. Mamas also experienced fewer adverse side effects compared with Beta Adrenergic Receptor Agents and Magnesium Sulfate.

So is Nifedipine the next great thing for the prevention of preterm labor? Perhaps. At the very least, it affords physicians and pregnant women another option for treatment while sparing infants potentially serious side effects.

31 responses to “Nifedipine in the Management of Preterm Labor”

  1. gaynell says:

    I took this med last year Along with labetol. And i miscarriage took twice, within one year and 6 month period 🙁 so spiritual. Torn………

  2. Darline says:

    So sorry to hear about your experience. I hope you have better success in the future. Best wishes!

  3. Elaine says:

    This was the only tocolytic used/discussed when I went into preterm labor and then 10 weeks of bed rest in Germany in early 2010. They seemed more advanced in both technology and medicine than what I’m experiencing in a top hospital here in 2014.

    I normally am hypotensive/have low blood pressure, but I didn’t have any unusual side effects, and nifedipine/Adalat stopped my frequent, strong, full-blown labor contractions in minutes.

    I hear horror stories about magnesium sulfate. I hope the FDA approves nifedipine for non “off-label” use shortly.

  4. Darline says:

    Elaine,
    Thanks so much for your comment. So glad you had a positive experience on Nifedipine and a healthy baby. Yes, Magnesium Sulfate is a tough one, but effective. Hopefully Nifedipine and other tocolytics with less dramatic effects will be available soon.

  5. me says:

    Im on it now still contractions but random instead of every ten minutes. I am 35 wks off in 7 now six days if I make it to then. Myqquestion is when I go off does labor start or could it wait?

  6. Darline says:

    Hi and congratulations for making it so far into your pregnancy! Nifedipine can be tricky, but thankfully it worked in your case.
    When you are taken off the drug, some will remain in your system for a time (blanking on the half life of Nifedipine at the moment). You won’t likely immediately go into labor, but as the drug washes out of your body, the contractions will begin and labor and delivery will take place. This normally isn’t more than a couple of days.

    FYI, sometimes women come off their drugs, the cerclage is removed, they are allowed to move about and then they go to term or even post dates. There really is no way to predict what your wee one is going to do (as the fetus initiates labor by getting into position in the pelvis, sending messages to your brain and kick starting a hormonal cascade that puts everything in motion!). So in answer to your question, your labor could start immediately (not typical but can happen) or it could take a few days to a few weeks as the drug washes out of your system. Good luck and let us know when your wee one arrives!!

  7. heather says:

    I’m 33 weeks pregnant and I was just put on procardia it makes me very tired but it has made my contractions slow an they aren’t as strong. I had bad contractions that made me not able to move they where 5 minutes apart so the tiredness is better to deal with

  8. Darline says:

    Heather,
    I am glad that procardia is working for you. Are you on bed rest or are they letting you go about your normal activities? Let me know as this is an interesting comment on the ongoing discussion of, “Is bed rest really necessary, or should a clinician simply treat the symptoms and let a pregnant mama maintain a modified lifestyle schedule?”

  9. heather says:

    I am 29 weeks pregnant and have been on procardia and bedrest for the past month due to preterm labor. The procardia occasionally gives makes me feel as though my heart is skipping a beat or is causing 3 beats close together then back to normal my pulse corresponds with this feeling. Doesnt happen everytime I take it (4x daily) but does it every so often approx an hour or two after taking.

  10. Darline says:

    Heather,
    Nifedipine is a Calcium Channel Blocker designed to slow heart rate and allow the heart to regulate. That being said, it has been shown to help reduce contractions that lead to preterm labor. Given that you likely didn’t have an arrhythmia (irregular heart rhythm) before starting Nifedipine, you may be experiencing some irregularity now with the drug. If it is very occasional, it is likely nothing to worry about. But if the rhythms become irregular, persistent, you experience dizziness, lightheadedness, shortness of breath or any other discomfort, notify your heatlh care provider immediately!!

  11. Bryana says:

    I took procardia with my last baby when I went into labor at 33 weeks. Combined with bed rest, it successfully delayed labor for 3 weeks. I am currently pregnant and in preterm labor (again). It started at 33 weeks and I have now been on bed rest and procardia for 2 weeks. No baby yet :-). Though I did experience some shortness of breath and low blood pressure, once I stopped the medication, I experienced no further side effects. In addition, my first son has shown no indication of negative repurcussions.

  12. Darline says:

    Bryana,
    I am thrilled to hear this! So glad that your first baby did so well and that this baby, too is doing well. Thanks so much for sharing your story and letting it inspire other mamas. If there is anything we can do to support you, please let me know! All the best and keep us posted.

  13. Jessica says:

    Thank you for this article, as a mama on bed rest who is on a nifedipine regimen currently, it’s quite interesting. I do have a question though! Can taking this medicine for the “relaxation” of contractions somehow inhibit the body’s “normal” labor progression? Here is a brief backstory: at 31 weeks (with twins) I was having regular contractions and a funneling cervix. I was given the steroid shots, along with two injections on different occasions to halt the contractions. OB immediately placed me on bed rest and a nifedipine prescription. We quickly found out that “every 4-6 hours” wasn’t cutting it and I had to take it every 4 hours on the dot, since my contractions start coming back at about the 3h30m mark.
    So, here is my question. I’ve been having NST done twice a week since being placed on this medication (on bed rest). The last two times, baby B has been “lethargic” with his heart rate, but ultimately passes the NST after I move around, drink ice water, etc. Well in all my pregnant paranoia I am now starting to worry about decreased fetal movement–something I’ve noticed in the past few days–and I’m wondering if taking this nifedipine is stopping labor that I “need to” be in, so to speak. If there is something wrong, or if the babies “need to” come out, my body would begin labor, right?
    My contractions have been slowly getting stronger and “breaking through” the nifedipine prescription, so I know it’s getting close. I will be 37 weeks on Thursday, and due to circumstances with where we live I am DESPERATE to keep them in past 37 weeks… But could it potentially be making things worse?
    Sorry this was SO long. Thank you for any insight you can provide.

  14. Darline says:

    Jessica,
    First, congratulations on making it to 37 weeks with twins!! That is no small feat and I applaud all your efforts. Now to the Nifedipine Question. When your body is ready for labor, you will go into labor. What caught my eye in your post is the fact that you are noting decreased fetal movement. This is something that you should bring to your OB’s attention and they should take a closer look at the babies’ movements. You are not being over reactive or a worry wart! This is serious stuff and I would contact your OB regarding this sooner rather than later. While I know that you want to keep them in past 37 weeks, sometimes in twins uterine space and placental supply necessitate that the babies be a bit early. Again, you made it to 37 weeks, so they are most likely going to be in really good shape. But I would address your concerns with your OB immediately and get his/her take. You may need an extra NST or you may need to be observed more closely. In any event, your OB needs to be in on this and to examine you and your babies to make the best treatment decision. Good luck and keep us posted, especially when your babies are born!!

  15. Emily says:

    I am almost 29 weeks with twins and have been on Procardia for almost 2 weeks now due to an irritable uterus. My doctor has also told me to stay off my feet. To date, I havent had any cervical change, and I still have frequent, BH-like contractions. If these “contractions” aren’t being stopped by the meds, I wonder if the risk of taking a class C drug like this is worth the potential harm to my babies. I know that the effects on humans aren’t well-studied but toxic effects have occurred in animals fetuses. I just don’t like the thought of taking something that could be potentially harmful, especially for another 5 weeks or so.

  16. Darline says:

    Hi Emily,
    While Procardia is a class C, this means that the potential risks may outweigh the benefits, but without it, there are potential adverse risks. This is always a difficult choice OB’s make. However, if you don’t have some sort of med to halt/reduce the contractions, you may go into labor and deliver your babies too early.

    I would recommend asking your OB what they feel is the benefit/risk ratio of taking Procardia. Express your concerns and ask if it is necessary since you are still having contractions. You can also ask if there is another alternative, something not a class C drug.

    The one thing I want to stress is NOT to stop the medication without your OB’s knowledge. This could most definitely have adverse side effects. Call/have an appointment as soon as you can and let me know if I can be of further assistance. Good luck and do let us know when you’ve delivered!!!

  17. Tipling says:

    I am 33 weeks and started on Nifedipine for pre-term labor 2 days ago. In the hospital they checked my BP before every dose. A couple of times it was low and they had to wait a bit before I could take it. Now that I am home, I find that when I take it, I get very dizzy if I get up and walk around and even sitting, I am light headed and feel off, like I have to catch my breath. I know dizziness is a side effect, I am just curious if I should be monitoring my bp. They didn’t say when I left the hospital. I will call my DR but just curious if others experience this and just deal with it or what is to be expected. Thank you.

  18. Darline says:

    Hi Tipling,
    I find it odd that OB’s don’t advise women to check there blood pressures. It’s so simple and gives so much pertinent information. There really is no contraindication, so I’d say, if you have a blood pressure machine handy, take your blood pressure-especially when you are feeling dizzy or just before taking a pill. If your blood pressure is low, check in with your OB. Also, you can check the accuracy of your machine by taking it to your next OB visit and seeing how the machine measures against the BP they take in the office.

    Nifedipine is notorious for making people dizzy, typically because it does such a good job of lowering blood pressure. If you are being prescribed nifedipine for preterm contractions, yet your blood pressure is/was normal, it’s no surprise Good Luck!!

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  20. Darline says:

    Hello,
    While I am sure that there is some benefit to Beets and their effect on blood pressure, this particular post is about Nifedipine’s use as a tocolytic, i.e. in the prevention of preterm labor. Nifedipine, which is an antihypertensive (Blood pressure lowering) medication is being used “off label” in the case of preterm labor.

    I am happy to review your literature on Beets and their effect on elevated blood pressure, but I have to say, I will not be recommending beets be used in lieu of medications to lower blood pressure in pregnant women or in women who have Pre-eclampsia, a potentially life-threatening condition comprised of elevated blood pressure, proteinuria, hemolysis (breakdown of red blood cells) and in severe cases elevated liver enzymes and low platelets. Thanks for your interest and if you would like, do send your literature for review.

  21. Yvette says:

    3 weeks of Procardia and I feel awful. I have been constantly experiencing headaches, shortness of breath, hot flashes, my ankles and calves are the same size, heart palpitations and all out tired. I looked for long term affects on the fetus, can’t find the information. I searched to see what would be the long affects on me and found nothing as well. i am 28 weeks with twins and the Procardia stopped the pain of the contractions but for 3 weeks steady they have been constant. I can say they are not close together but they are still constant. I saw that I have to be weaned off of the medication, which is another issue for me. Why would I be prescribed medications what makes me ill and hurts me this way? What is the point of stopping preterm labor when I’m not sure what will be wrong with my children long term OR if in 5 years my heart will be messed up in some sort of way dealing with these meds. I am now weaning myself off of the medication, if there is nothing else that can help me then I pray my children are ok if born early.

  22. Darline says:

    Yvette,
    I am so sorry that you are going through all of this! Procardia has been effective in halting labor contractions, but as you can see, it can have some ghastly side effects. I would definitely call into your OB’s office and let them know the symptoms which you are experiencing. While Pericardia has been used extensively for high blood pressure and to halt preterm labor contractions, you should not be feeling this poorly. Definitely contact your OB and schedule an office visit. Take care and let us know how you are doing and if we can help.

  23. Martha Sanchez says:

    I am 17 weeks. I pprom at 15 weeks.
    My ob has prescribed Nifedipine help me reach viability. Has anyone else taken it this soon in pregnancy

  24. Darline says:

    Martha,
    I have not heard of Nifedipine being used in cases of PPROM. Typically its used for hypertension and preterm labor. While PPROM is a form of preterm labor, once membranes are ruptured, I am not sure that Nifedipine can help the pregnancy. I would ask your OB to sit down and describe in detail how this works and what is his/her intended outcome. Good Luck!!!

  25. Kouvonia says:

    I’m 33 weeks and 2 days. Prescribed nifedipine yesterday after strong, frequent contractions. I’m also currently dilated 1cm so I’ve been put on bed rest. So far no side affects of the medicine just hope this works as good as everyone else’s and I deliver my baby closer to my due date. Thanks for enlightening me on this medication

  26. Deborah says:

    At what week of pregnancy can a woman starts to take nifedipine?

  27. Darline says:

    Pretty much anytime her blood pressure rises. If she has blood pressure significant enough to warrant medication, it’s time to take it. Elevated blood pressure is more of a risk to mamas than Nifedipine. If you are concerned, ask your OB for further clarification. Good Luck!!

  28. Krista says:

    I’m 25 weeks and started having frequent contractions due to my subchorionic hematoma at 20 weeks and again a few days later at 21 weeks. I was given Indocin at L&D and continued it at home for a total of 48 hours.They also prescribed Procardia in case my contractions returned, which they did about 2.5 weeks later at 24 weeks. I’ve been told to take it until my SCH is gone and then we’ll try tapering. I still feel some occasional contractions, but it’s definitely helping a ton! I’m hoping once this SCH (this is #2 SCH for this pregnancy) is gone from US scan – maybe at my 27 week visit, and we taper off meds that I can hold off on labor!

  29. Darline says:

    Congratulations Krista!!
    All the best to you and your little one. Hope things go well and you can taper off meds at 27 weeks. Keep us posted.

  30. Joan says:

    I’m currently 22weeks pregnant and i was prescribed 10mg 2x/day. Can i continue with this dosage until i’m about 37 weeks? i have an irritable uterus which led to cervical dilation/funneling at 20weeks.

  31. Darline says:

    Joan,
    This is a question you should pose to your OB. Ask how long you need to take the medication and about any potential side effects for both yourself and your baby. They should be able to ease any of your anxiety and answer your question. Good Luck!!

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