A study shows that frozen embryos have a higher risk of pregnancy complications associated with high blood pressure


Pregnancy from in vitro fertilization utilizing frozen embryos is associated with a higher risk of complications associated to high blood pressure or hypertension than when utilizing freshly fertilized embryos or when conceived naturally.

That’s in line with a study revealed Monday within the American Heart Association’s Journal of Hypertension, which included knowledge on greater than 4.5 million pregnancies over almost three a long time in three European international locations: Denmark, Norway and Sweden.

The knowledge confirmed that the risk of pregnancy complications associated to high blood pressure was higher after frozen embryo switch in comparison with naturally conceived pregnancies, and the risk after recent embryo switch was much like naturally conceived pregnancies.

More analysis is required to find out whether or not related findings emerge within the United States.

Researchers from the Norwegian University of Science and Technology and different establishments in Europe analyzed medical registers of births from Denmark between 1994 and 2014, Norway between 1984 and 2015, and Sweden between 1985 and 2015. 4.4 million pure pregnancies, 78,300 recent embryo transfers and 18,037 frozen embryo transfers.

The researchers in contrast the risk of hypertension in pregnancy by group and located that the unadjusted risk of such problems was 7.4% after embryo freezing, 5.9% after recent embryo switch, and 4.3% after pure conception. The knowledge additionally confirmed that untimely pregnancies resulting from frozen and recent embryo transfers had been 6.6% higher with frozen and eight.1% with recent embryos in comparison with 5%.

“Frozen embryo switch is now turning into extra frequent worldwide, and up to now few years some medical doctors have begun to keep away from transferring new embryos as a way to routinely freeze all embryos of their scientific apply,” lead study writer Dr. Cindre H. Petersen, Ph.D. This was introduced by a researcher on the Norwegian University of Science and Technology in Trondheim, Norway, in a press launch on Monday.

“In abstract, though most IVF pregnancies are wholesome and uncomplicated,” she stated, “this evaluation confirmed that the risk of gestational hypertension is considerably higher after frozen embryos in comparison with pregnancies from recent embryo switch or pure conception.”

Petersen added, “Our outcomes recommend that all advantages and potential dangers needs to be fastidiously thought-about earlier than freezing all embryos in scientific apply.”

In a study by the researchers, these findings had been “in settlement with earlier population-level research” and confirmed an elevated risk of hypertensive problems throughout pregnancy after frozen embryo switch.

A massive French study final 12 months, introduced on the annual on-line assembly of the European Society of Human Reproduction and Embryology, additionally discovered a higher risk of preeclampsia and hypertension in pregnancies from frozen-thawed embryos. When the uterus is ready for implantation with hormone substitute therapies.

“The affiliation between frozen embryo cycles and gestational hypertension has been recognized for a while, and the present query is, ‘Is freezing for everybody?’ There is an energetic dialogue concerning the professionals and cons of amongst fertility medical doctors,” Dr. Ying Cheong, a professor of reproductive medication on the University of Southampton, advised the UK-based Science Media Center in July. He was not concerned in both study.

“There are two necessary factors right here, firstly, when frozen embryo switch know-how adjustments reproductive medication, FET ought to solely be carried out the place it’s clinically applicable, and secondly, clinicians and scientists in early improvement and later start and after, in my view, the sector of analysis continues to be poorly supported. obtained and studied,” Chong stated.

The new study did not assess what could be driving this hyperlink between frozen embryo switch and high blood pressure, however some IVF medical doctors query whether or not it is actually new. frozen.

“There is one factor that is unclear: is it from the present embryo freezing process or the protocol used?” Most IVF medical doctors consider that the most recent analysis and proof suggests that it’s the treatment protocol, not the IVF process itself. Aimee Eywazzadeh, a reproductive endocrinologist in San Francisco who was not concerned within the new study, wrote in an electronic mail to CNN on Monday.

“There are other ways to organize the uterus for switch,” she stated. One protocol entails the corpus luteum cyst, a fluid-filled mass that types within the ovaries and performs an necessary function throughout pregnancy as a result of the corpus luteum produces the hormone progesterone wanted throughout pregnancy. Another protocol depends on medicine that mimic ovulation.

“Studies present that corpus luteum deficiency will increase the risk, and because of this, frozen switch could also be associated with a higher risk of preeclampsia,” Eyvazzadeh wrote.

Overall, the brand new study is “essential for these caring for post-IVF pregnancies,” he wrote. IVF after frozen embryo switch will increase the risk of preeclampsia.


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