Lack of Corpus Luteum May Impair Cardiovascular System in IVF Pregnancies

By Marilynn Larkin

August 13, 2019

NEW YORK (Reuters Health) - A corpus luteum (CL) plays a "critical role" in the transformation of a woman's cardiovascular system early in pregnancy, and lack of a CL common in IVF pregnancies - may raise the risk of pre-eclampsia, researchers say.

"Women who conceive by IVF using frozen autologous or fresh/frozen donor embryos in an 'artificial' cycle lack a CL - the major source of reproductive hormones during early pregnancy - due to hypothalamic-pituitary suppression," Dr. Kirk Conrad of the University of Florida College of Medicine in Gainesville explained in an email to Reuters Health.

"These women demonstrated generalized impairment of the cardiovascular adaptations that normally transpire during the first trimester," he said. "Thereafter, cardiovascular function mostly recovered in the second trimester, coincident with placental maturation and hormone secretion."

Dr. Conrad and colleagues enrolled women conceiving: 1) naturally without IVF (singleton pregnancies/single CL); 2) by transfer of a frozen-thawed embryo produced using donor or autologous oocytes or fresh donor oocyte-generated embryos in a programmed, suppressed cycle (absent CL); or (3) after ovarian stimulation, IVF, and fresh embryo transfer (multiple CL).

Each group had 19 to 26 women. Race, parity, maternal smoking, and history of hypertensive disease of pregnancy were similar.

As reported online July 29 in Hypertension, the team evaluated maternal cardiovascular adaptations of gestation during the follicular phase before conception, six times during pregnancy and, on average, 1.6 years post-partum.

In the first trimester, compared with women with one or more CLs, those who conceived without a CL had significant attenuation, or absence, of the expected increases of cardiac output, left atrial dimension, peak left ventricular filling velocity in early diastole (E wave velocity), peripheral/central arterial pulse pressure ratio, and global arterial compliance - as well as a decrease in the augmentation index.

By contrast, first-trimester cardiovascular adaptations were comparable among women with one and more than one CL.

After the first trimester, cardiovascular measures recovered in women without a CL, except for E wave velocity, which remained depressed.

"From the standpoint of the physiologist, these findings implicated CL hormone(s) in the maternal changes of the cardiovascular system during the first trimester," Dr. Conrad said. "Of importance to the clinician is that the cardiovascular derangements during early pregnancy in women lacking a CL were shown to be associated with increased risk of preeclampsia."

"Whether absence of CL hormone(s), cardiovascular dysregulation in early pregnancy, and enhanced preeclampsia risk are causally linked needs further study," he said. "If increased preeclampsia risk in pregnancies conceived without a CL is corroborated by a randomized clinical trial comparing autologous frozen embryos transferred in an artificial (0 CL) versus natural (1 CL) cycle, then a natural cycle might be recommended for some women, or eventually, replacement of the missing CL hormone(s) might prove to be salutary."

Dr. Basky Thilaganathan of St. George's University of London, UK, author of a related editorial, commented by email, "Although it is entirely plausible that CL factors may directly influence early pregnancy maternal cardiovascular adaptation as the authors suggest, their data actually shows that cardiovascular maladaptation predated conception and the development of the CL in cases of preeclampsia."

"These findings are consistent with the finding that the majority of women without a CL required ovum donation for premature ovarian insufficiency - a condition associated with increased cardiovascular dysfunction and morbidity," he told Reuters Health.

"This study highlights the emerging evidence that maternal cardiovascular dysfunction predisposes to the development of preeclampsia, predominates in the preeclamptic state and persists in the postnatal period," he concluded.


Hypertension 2019.