Frozen embryo transfer associated with hypertension risk during pregnancy

Research highlights:

• Assisted reproductive pregnancies with frozen embryos may have a 74% higher risk of developing hypertensive disorders than natural pregnancies.
• In contrast, the risk of hypertensive disease in pregnancies with fresh embryo transfer was similar to that in spontaneous pregnancies.
• High blood pressure during pregnancy can be a sign of pre-eclampsia. This is a serious and potentially life-threatening pregnancy complication for the mother and fetus.

Embargoed until Monday, September 26, 2022 at 4:00 AM / 5:00 AM ET

Dallas, Sept. 26, 2022 — In vitro fertilization (IVF) using frozen embryos may be associated with 74% higher risk hypertensive disorders during pregnancyaccording to a new study published today high blood pressure, Journal of the American Heart Association. In contrast, this study found that pregnancies from fresh embryo transfer (implanting fertilized eggs immediately after in vitro fertilization (IVF) instead of frozen embryos) and pregnancies from spontaneous pregnancies develop hypertensive disease. It turns out that we share the risk.

High blood pressure during pregnancy often signals preeclampsiacomplications of pregnancy, including persistent hypertension, which can endanger the health and life of the mother and fetus. In the United States, approximately 1 in 25 pregnancies develops pre-eclampsia.according to the American Heart Association.

One of the available IVF treatment processes utilizes frozen embryos. After the eggs are fertilized with sperm in the lab, they are frozen using a cryopreservation process and thawed at a later date and transferred to the uterus. This technique is becoming more popular due to significant improvements in cryopreservation techniques or cryopreservation methods that started in the late 2000s and because more patients are choosing to freeze their embryos. However, frozen embryo transfer is known to have a higher risk of hypertensive disease during pregnancy than natural pregnancy or fresh embryo transfer. However, prior to this study, it was unclear whether this was due to the freezing process or parental risk factors.

“Frozen embryo transfers are now becoming more and more common around the world. In the last few years, some doctors have begun skipping fresh embryo transfers and routinely freezing all embryos in their clinical practice. The so-called “freeze everything” approach. ‘ said Cindle H. Petersen, M.D., Ph.D., lead author of the study. Fellow of the Norwegian University of Science and Technology, Trondheim, Norway.

The researchers looked at national data from medical birth registers in Denmark, Norway and Sweden of approximately 2.4 million women aged 20 to 44 who delivered single deliveries during the study period from 1988 to 2015. was investigated. These data are population-based studies that also include comparisons of women who have had both IVF pregnancies and spontaneous pregnancies, called sibling comparisons. was used to determine whether it was due to

The study included more than 4.5 million pregnancies, of which 4.4 million were spontaneous pregnancies. Over 78,000 pregnancies were fresh embryo transfers. Over 18,000 pregnancies were frozen embryo transfers. Among all pregnancies, over 33,000 were grouped for sibling comparison. This is a mother who became pregnant through her two or more of these methods. This study is the largest to date using sibling comparisons. The odds of developing hypertensive disease during pregnancies after fresh versus frozen embryo transfer compared with spontaneous pregnancies were adjusted for variables such as year of birth and maternal age.

“In summary, although most IVF pregnancies are healthy and uncomplicated.”This analysis found that the risk of hypertension during pregnancy was significantly greater after frozen embryo transfer compared with pregnancies resulting from fresh embryo transfer or natural conception. was found to be high.”

Specifically, the study found that:

• In a population analysis, women who became pregnant as a result of frozen embryo transfer were 74% more likely to develop a hypertensive disorder during pregnancy compared with women who conceived naturally.
• Among women who had both natural and frozen embryo transfer IVF conceptions (sibling comparison), the risk of hypertensive disorders in post-frozen embryo transfer pregnancies was twice as high as in pregnancies resulting from spontaneous pregnancies.
• Pregnancies resulting from fresh embryo transfer were not at increased risk of developing hypertensive disease compared with spontaneous conception, either in population-level analyses, or in sibling comparisons.

“Our sibling comparison indicates that the higher risk may not be caused by factors associated with the parents, but may involve some IVF treatment factors.” Studies should investigate which parts of the frozen embryo transfer process may influence the risk of hypertension during pregnancy.”

The average age of women who gave birth after in vitro fertilization was 34 years for frozen embryo transfer, 33 years for fresh embryo transfer, and 29 years for spontaneous conception. Approximately 7% of babies conceived from frozen embryo transfers were born preterm (before 40 weeks of gestation) and her 8% of babies after fresh embryo transfer were born preterm, compared to 5% of her naturally conceived babies. was.

In addition to pre-eclampsia, the researchers defined hypertensive disorders during pregnancy as a combination of outcomes including: pregnancy hypertensioneclampsia (seizure onset in preeclamptic patients) and chronic hypertension superimposed on preeclampsia.

One of the limitations of this study was the lack of data on the type of frozen embryo cycle, so it was difficult to pinpoint exactly what part of the freezing cycle or cryopreservation may contribute to the increased risk of hypertensive disease. Could not identify. Another limitation is that data from Scandinavian countries may limit the generalization of findings to people in other countries.

“Our results highlight the need to carefully consider all benefits and potential risks before freezing all embryos as a routine part of clinical practice. “It’s important to have a comprehensive and individualized discussion between doctors and patients about the benefits and risks of transplantation,” said Petersen.

Co-authors are Kjersti Westvik-Johari, MD, Ph.D. Anne Laerke Spangmose, MD, Ph.D.; Anja Pinborg, MD, Ph.D.; Liv Bente Romundstad, MD, Ph.D.; Christina Bergh, MD, Ph.D.; Bjørn Olav Åsvold, MD, Ph.D. D.; Dr. Mika Gisler. Aila Tiitinen, MD, Ph.D.; Ulla-Britt Wennerholm, MD, Ph.D.; and Signe Opdahl, MD, Ph.D.

This study was funded by the Norwegian University of Science and Technology, the Nordic Council of Ministers and NordForsk, the Central Norwegian Regional Health Authority, the Nordic Union of Obstetrics and Gynecology, the Interreg Øresund-Kattegat-Skagerrak European Regional Development Fund and Research. Norwegian Council Center of Excellence.

Research published in the American Heart Association scientific journal is peer-reviewed. The statements and conclusions in each manuscript are solely those of the study authors and do not necessarily reflect the policy or position of the Society. The Society makes no representations or warranties as to their accuracy or reliability. The association receives funding primarily from individuals. Foundations and companies (including pharmaceuticals, device manufacturers, and other companies) also make donations to fund specific programs and events of the association. The Society has strict policies to prevent these relationships from affecting the content of science. Income from pharmaceutical companies, biotech companies, device manufacturers, health insurers, and the association’s overall financial information are available. here.

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