Authors of a paper on cryonic preservation during pregnancy found no studies and proposed policies for cryonics organizations and two hypotheses for researchers on delivering cryoprotectant solution to the fetus
Authors of a paper on cryonic preservation during pregnancy found no studies and proposed policies for cryonics organizations and two hypotheses for researchers on delivering cryoprotectant solution to the fetus
On October 21, Frontiers in Reproductive Health published a paper by Carrie Radomski, a director of several cryonics-related organizations, and Natasha Vita-More, a member of the cryonics organizations Alcor and Tomorrow Bio.
Cryonics preserves the body after legal death. A cryoprotectant solution is pumped through the blood vessels so that tissues enter a glassy state during cooling rather than forming ice. Of 1411 recorded members of Tomorrow Bio and Cryonics Institute, 171 are women aged 20–50, roughly one in eight members (2024 data; Alcor has no age breakdown). According to the authors, the organizations’ policies provide for neither pregnancy testing nor procedures to follow if a member is pregnant, although early pregnancy may have no outward signs.
The authors describe the pregnant woman and fetus as “a single physical body containing two biologically distinct systems”: both undergo the same procedure, but they may respond differently to the solution and to cooling. Their first hypothesis is that, when the solution is pumped through the blood vessels throughout the body, it crosses the placenta slowly. Its concentration would therefore be lower in the fetus than in the mother, potentially allowing ice to form in fetal tissues during cooling. Their second hypothesis is that this concentration difference depends on the stage of pregnancy. As pregnancy progresses, the placental barrier becomes thinner, which may speed up exchange and reduce the difference. However, fetal mass and the volume throughout which the solution must be distributed also increase, so the difference could instead grow. Equal concentrations in the mother and fetus would refute the first hypothesis; the absence of a relationship with the stage of pregnancy would refute the second. The authors propose testing these hypotheses in pregnant guinea pigs because the barrier between maternal and fetal blood resembles that in humans.
Timing presents another obstacle: circulation must be restored and the body cooled quickly after legal death. In the United States, brain death is legally recognized as death, but physicians may maintain a pregnant woman’s bodily functions with life support for weeks after brain death to allow the fetus to mature. In 35 cases reported in the literature, support continued for an average of about seven weeks. Cryonic preservation is postponed while life support continues. During that time, the initial brain injury and complications of prolonged intensive care, such as infections, may damage maternal tissues. The authors propose deciding how many weeks to continue support on a case-by-case basis, weighing the condition of the mother and fetus, the law, and the woman’s wishes.
The law can override a family’s wishes. In late November 2013, Marlise Muñoz was declared brain-dead at 14 weeks of pregnancy. The hospital kept her on life support for about two months against her family’s wishes because Texas law prohibits withdrawing life support from a pregnant woman. In January 2014, a court ruled that the prohibition did not apply to her because she was legally dead. The authors advise organizations to record each woman’s decisions in her membership documents: whether to maintain her bodily functions, whether to prioritize the mother or fetus, and what to do with the fetus if it is removed. These decisions would need to be checked against local law: many US states restrict the applicability of advance directives during pregnancy.
The authors acknowledge a substantial objection: while preserving one person remains an unresolved problem, studying the more difficult case of two systems may be a poor use of limited research resources. They therefore propose conducting experiments alongside programs on freezing gametes and embryos. On organizational policies, they write:
“In short, organizational policy in this area should precede practice.”