Q&A: Major differences found among current guidelines for managing twin pregnancies
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Key takeaways:
- Twin pregnancy guidelines offer different advice pertaining to preterm birth, aspirin use, growth restriction definitions and timing of delivery.
- Key new research areas involve genetic screening of twin fetuses.
Current guidelines for the management of twin pregnancies differ regarding recommendations about preterm birth screening and prevention, aspirin use to prevent preeclampsia, fetal growth restriction definitions and delivery timing.
Researchers reviewed 28 clinical practice guidelines published by 11 professional societies, of which 13 focused on twin pregnancies. Most of the clinical guidelines were published within the past 3 years. Researchers identified recommendations on first-trimester care, antenatal surveillance, preterm birth, preeclampsia, fetal growth restriction, gestational diabetes, and timing and mode of delivery.
Results, published in the American Journal of Obstetrics & Gynecology, highlighted considerable disagreement between guideline recommendations especially among preterm birth screening and prevention, aspirin use to prevent preeclampsia, fetal growth restriction definitions and delivery timing. In addition, researchers noted areas of twin pregnancy management that have limited guidance, such as implications of the “vanishing twin” phenomenon, risks and technical aspects of invasive procedures, nutrition and weight gain, physical and sexual activity, use of the optimal growth chart, gestational diabetes diagnosis and management, and intrapartum care.
Healio spoke with study co-author Vincenzo Berghella, MD, professor, director in the division of maternal-fetal medicine and director of the Maternal-Fetal Medicine Fellowship Program at Sidney Kimmel Medical College at Thomas Jefferson University, about these findings and how to mend gaps in recommendations on twin pregnancy management.
Healio: How common are twin pregnancies and what complications are most common with twin pregnancies?
Berghella: Twin pregnancies are pretty common. They used to be only 1% of the population, but, for example, in the U.S. about 3% of pregnancies are now with twins. This is because women tend to have twins later in life and mean age during pregnancy has been rising. Also, assisted reproductive technologies like IVF are associated with twin pregnancies and there are more and more pregnancies using these procedures. There are also some countries, for example, West Africa, that have a much higher incidence of twins. Interestingly, in Asia the incidence is a little bit less.
The most common complications are the big complications of any pregnancy, such as preterm birth, preeclampsia, fetal growth restriction, requiring a cesarean section for delivery and many others, but those are the top ones.
Healio: How do twin pregnancies differ from singleton pregnancies?
Berghella: They differ because there are two babies instead of one, to be simple. But the issue is, while the lay public could think, “I’m carrying a pregnancy once to carry two babies, so I get two for one,” it’s much more difficult to carry that pregnancy so that you have two healthy babies. There’s a much higher chance of carrying a healthy baby in a singleton pregnancy to term without preeclampsia, without fetal growth restriction, etc. I always joke around that I’m all for having 10 kids per family. It’s good for obstetrics, but you usually should have one baby at a time because twins present higher risks for surgery or complications.
Healio: What are the most common recommendations observed in current clinical guidelines for managing twin pregnancies?
Berghella: We’ve identified four areas, in particular, with discrepancies. There were not a lot of similarities across guidelines, but there were some discrepancies:
- screening and prevention of preterm birth, which is a major complication;
- using aspirin to prevent preeclampsia, which is another major complication. It would be good to agree that every woman with twins should take aspirin to prevent preeclampsia, but the guidelines did not agree;
- the definition of fetal growth restriction, meaning one of the twins is too small. If that happens, then the baby has risks for dying or having complications, and we need to have some kind of management for that. If we don’t even agree on whether a twin is small or not during pregnancy, then it’s hard to manage; and
- timing of delivery, which is when exactly you deliver when you’re carrying twins.
Healio: What recommendations for twin pregnancy management are missing in current guidelines?
Berghella: In general, the guidelines were pretty comprehensive. Some were obviously larger and more comprehensive than others. An area in which there are a lot of changes is genetics and how you screen twin pregnancy. Twin pregnancy has a risk for more genetic complications in the babies, more structural anomalies and more birth defects. As genetics change, the guidelines should be more up-to-date on genetic screening, which is probably the area of the most active research.
Healio: Should physicians treating women with twin pregnancies pick and choose certain parts of a guideline or just choose one guideline, like the ACOG guideline, and follow everything that one says?
Berghella: In the U.S., while unfortunately there is no national health service that says use to use ACOG for pregnancy-related guidance, that is the accepted guidance. Nothing is perfect, but practitioners in the U.S. should be aware that that’s the standard, including for twins, and if they don’t do what ACOG recommends, they should document that. Sometimes there are occasions to deviate from the guideline. But they should be aware of it, and they should explain why they chose not to use it case by case. For other countries, if there is no national guidance, I think that the [International Federation of Gynecology and Obstetrics] international guidelines are good to use. We reviewed Canadian guidelines, which are good, and they should probably be the lead ones there. The U.K. has Royal College guidelines, which are the standard there. Many countries — France, Germany, Australia and New Zealand — have national guidelines and usually those are the standard to use.
For somebody at a research level, it’s good to be aware of this study. It’s an important paper so that people now have all of the options for twin pregnancies right on the chart. They can look at all the best guidelines in the world and see, for example, whether five of the seven guidelines suggest that twins should have an early anatomy scan. I think that that’s probably a good thing to do. Most people agree. We’re hoping that the different societies who are making guidelines look at this paper and say, “We’re in the U.K., but we forgot to talk about early screening. Everybody else does, so we can put it in.” By looking at the differences, we can all the help the other ones to be more aligned, so that there is less difference.
Healio: In the study, you mention disagreement among guidelines regarding screening and prevention of preterm birth, aspirin use to prevent preeclampsia, defining fetal growth restriction and timing of delivery. What future research is required to make consistent recommendations for these areas?
Berghella: That’s a great question. I am not sure that it’s future research that we need because, hopefully, we’re looking at similar research, but came up with different conclusions depending on how they interpreted their research and on their own biases. It would be good to have some policy changes or even some political changes. For example, in the U.S., someone higher than the doctor’s level, at the political level or the NIH or FDA, who can say, “In general, for pregnancy, we recommend following the American College of Obstetrics and Gynecologists.” This is kind of an unwritten understanding in the U.S., and every other country could do something similar. Then this higher-level figure could decide what the official guidelines would be because how we are right now is too confusing.
Healio: Is there anything else you would like to add?
Berghella: It’s important in general to follow guidelines. The important thing is to be aware. Historically, 30, 40 or 100 years ago, it was OK, maybe, to practice by common sense, but there’s so much science, so much research and so many publications every month. It’s hard to read everything, but that’s what the guidelines are there for. One of the messages is to follow at least one guideline that you believe is the standard for your local needs and location.
For more information
Vincenzo Berghella, MD, can be reached at vincenzo.berghella@jefferson.edu.