(Bloomberg News) When Heidi Sanders, 31, was facing cervical cancer in July 2008 she was concerned she wouldn't be able to have children in the future, so she had 15 of her eggs and 14 embryos frozen.

"It was a huge source of comfort for me while I was going through treatment that a part of me might survive if I could not," said Sanders, a gallery director in Manhattan.

Sanders told her boyfriend-now husband-and parents that she wanted them to try and use her genetic material to conceive a child if she died.

Most states don't have laws governing the inheritance rights of children conceived after a parent dies even as the use of assisted reproductive technologies has doubled in the U.S. over the last decade, according to the Centers for Disease Control and Prevention in Atlanta.

"There are situations where it's not so clear that a person would have wanted to be deemed a parent after death," said Laura Twomey, who specializes in estate planning and is a partner at Simpson Thacher & Bartlett LLP in New York. Questions also arise over whether posthumously conceived children may benefit from a relative's trust: "Is that what Grandma would have wanted?" Twomey said.

Eggs, sperm and embryos used in procedures such as in vitro fertilization and artificial insemination can be frozen and stored indefinitely, said Nicole Noyes, a physician and professor at New York University School of Medicine and co- director of the egg-freezing program at NYU Fertility Center.

Wide Open Field

About 132 women have frozen their eggs in the past year at NYU's center in New York, up from about 20 three years ago, said Noyes, who treated Sanders. Some patients are trying to preserve their ability to get pregnant later in life, while about a quarter of them have cancer and may become infertile or sterile through treatments, Noyes said.

"If any of these young women die, what are the heir rights for these eggs?" she said. "It's a wide open field. This is new."

One cycle of in vitro fertilization at NYU, in which eggs are retrieved and embryos are transferred to the uterus, costs $10,565, if insurance doesn't cover it, according to the center. Patients with any extra eggs or embryos may freeze them for $1,500 the first year and $1,000 each additional year. The center requires people to fill out forms stating what they want done with the genetic material if they die, Noyes said.

Sanders specified in her paperwork that the eggs and embryos would go to her husband in the event of her death, she said. She said she didn't have a will.

State Issue

Disputes over whether children conceived after a parent's death have inheritance rights to the deceased mother or father's estate and family trusts will happen more frequently, said Joshua Rubenstein, national chair of trusts and estates at Katten Muchin Rosenman LLP in New York. Rubenstein has settled six such cases in the last seven years. They've generally revolved around instances where a wife who has been distanced from her deceased husband's family has a child posthumously and wants to access money in a trust fund, he said.

The issue falls to the states rather than the federal government because it involves parentage, said Kristine Knaplund, a professor at Pepperdine University School of Law in Malibu, California, who specializes in estates and bioethics.

New York Rule

In Florida, posthumously conceived children aren't heirs of a deceased parent unless provided for in a will, Knaplund said. California requires evidence of a parent's wishes and notification to the estate of the intent to use the frozen genetic material. Implantation must occur within two years of a decedent's death. Louisiana has a similar rule saying the child must be born within three years.

New York State amended its rules in 2006 regarding a parent with a will who may not have updated it before dying to provide for additional children. The statute says in that situation a child conceived after a parent dies doesn't have rights to a portion of the estate.

A 2007 case before the Surrogate's Court of New York County centered on whether two children conceived by means of in vitro fertilization years after their father died could inherit from trust agreements set up by a grandparent, according to court documents.

Judge Renee R. Roth ruled the infants were deemed to be descendants for purposes of the trusts. "There is a need for comprehensive legislation to resolve the issues raised by advances in biotechnology," the opinion said. The ruling was limited to the facts of that specific case, Rubenstein, the estate lawyer, said.

Uniform Code

Three states-Colorado, North Dakota and Utah-have adopted amendments in the Uniform Probate Code since 2008 addressing the issue, said Michael Kerr, legislative director for the Chicago-based Uniform Law Commission. The commission is a non-profit, governmental organization that establishes statutes states may adopt when it's important to have consistency nationally. The provisions are pending in Minnesota and New Mexico, Kerr said.

The UPC says a child conceived posthumously must be in utero no more than 36 months after a parent's death-or born within 45 months-to inherit. That gives a spouse or partner time to grieve and for failed attempts to achieve pregnancy, while not leaving an estate open indefinitely, said Lawrence Waggoner, a professor at the University of Michigan Law School, who helped draft the amendments.

Claims on Relatives

The Code also stipulates that a child who is deemed an heir to a parent may also inherit from a relative of that parent, Waggoner said. By contrast, children born from an anonymous sperm or egg donor don't have a claim to the inheritance of the donor under the Code, he said.

Documents such as a will or forms signed at a fertility center specifying a parent's wishes about a posthumously conceived child can override the UPC provisions, Waggoner said.

A provision in a trust, for example, might include language such as "any child born to my husband and me shall include a posthumously conceived child by me by means of assisted reproduction" as long as that baby "is born during my husband's lifetime and my husband has acted as such child's legal guardian," said Teresa Baird, an attorney at Denver-based law firm Fairfield and Woods PC.

Be Proactive

"Don't count on a statute or judge correctly interpreting what your intentions are," said Bruce Fowler, a partner at Fairfield and Woods PC, who has clients with frozen genetic material. "If you do have genetic material preserved you need to do the thoughtful planning and be proactive."

Grandparents should also specify whether they want any grandchildren conceived after their child's death using the deceased child's preserved genetic material to inherit from any trust they set up, Fowler said.

Sanders said she is cancer-free after treatment and a hysterectomy. She and her husband still have some eggs and embryos frozen and her sister is carrying their first child.

"We're expecting in March," she said.