A study of 4.5 million women discovered that the danger increased when frozen embryos were utilized instead of fresh embryos. According to a study published Monday in the journal Hypertension, utilizing frozen embryos for in vitro fertilization increases the risk of hypertensive diseases, including preeclampsia, during pregnancy.
While the association between frozen embryo transfers and high blood pressure is not new, the current study, which includes data from millions of Norwegian women, provides a clearer picture of the risk. The study was also the largest to date to include data on multiple pregnancies in women.
The risk of hypertensive disorders was modest overall: about 7.4% in women who used frozen embryos, 5.6% in women who utilized fresh embryos, and 4.3% in women who conceived spontaneously.
When the researchers controlled for other factors that could cause hypertensive disorders during pregnancy, such as age, pre-existing high blood pressure, and obesity, they discovered that using frozen embryos increased the risk by 74% when compared to IVF using fresh embryos or a naturally conceived pregnancy. Furthermore, they discovered no statistically significant difference in risk between women who conceived spontaneously and those who used fresh embryos for IVF.
After the 20th week of pregnancy, approximately 75% of the women in the research who acquired hypertensive problems developed preeclampsia, which is defined by dangerously high blood pressure and symptoms of liver or kidney damage. If left untreated, it can be fatal.
“We wouldn’t be concerned if our study only found an association for isolated gestational hypertensive disorders, but we discovered in our extra analysis that there was a strong association between frozen IVF and preeclampsia,” said the study’s lead author, Dr. Sindre Petersen, a doctoral fellow at the Norwegian University of Science and Technology.
High blood pressure during pregnancy may not necessarily result in difficulties, but doctors must constantly watch these women for signs of preeclampsia. According to the Centers for Disease Control and Prevention, around one in every twelve women in the United States has high blood pressure during pregnancy, and approximately one in every twenty-five pregnant women has preeclampsia, according to the American Heart Association.
The latest study examined data from 4.5 million Norwegian pregnancies from 1988 to 2015. The study compared 4.4 million spontaneously conceived pregnancies to little over 78,000 IVF pregnancies conceived with a fresh embryo and around 18,000 with a frozen embryo. Approximately 33,000 pregnancies occurred in women who had more than one pregnancy.
According to preliminary CDC data, over 80,000 kids born in the United States in 2020 will be the result of assisted reproductive technology, which includes IVF.
“The truth is that women are now older when they have their first baby,” said Dr. Anum Minhas, a cardio-obstetrician at Johns Hopkins Medicine who was not involved in the new study.