IVF medication dosing change could increase chance of successful pregnancy in obese women

IVF medication dosing change could increase chance of successful pregnancy in obese women

Obese women may need a different dose of medication than normal weight women in order to successfully have their eggs harvested for in vitro fertilization (IVF), according to a new study published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism (JCEM).

IVF is a type of assisted reproductive technology used to help women become pregnant. More than 1 percent of all infants born in the United States each year are conceived using assisted reproductive technology, according to the U.S. Centers for Disease Control and Prevention.

IVF involves mixing sperm with an egg outside the body and then transferring the resulting embryo into the uterus. The goal is to harvest many eggs to ensure a successful IVF cycle. As part of the egg harvesting process, women receive a medication called a GnRH antagonist to prevent the brain from giving the ovulation signal too early and ruining the egg harvest.

"If the GnRH antagonist clears from a woman's body too quickly, there is a risk that the brain will signal the body to discharge the eggs from the ovaries too early," said one of the study's authors, Nanette Santoro, MD, of the University of Colorado at Denver. "We were surprised to find obese women were more likely to experience this, and it may be one reason why overweight and obese women have a higher rate of unsuccessful IVF cycles than normal weight women do."

The interventional study examined the rate of medication absorption in 10 obese and 10 normal-weight women. Researchers gave each participant a dose of a GnRH antagonist used in IVF procedures. To determine how quickly the medication was absorbed, the participants had their blood frequently sampled for six hours, beginning eight hours after the medication was first administered.

The study found the GnRH antagonist cleared out of the obese women's systems more quickly than the normal-weight women. In addition, half of the obese women had a rebound of luteinizing hormone - the hormone that causes the body to release eggs - during the 14-hour monitoring period.

"Our findings indicate obese women may need a different or increased dosing regimen to improve fertility treatment outcomes," Santoro said. "Given the cost of IVF and stress of infertility, it is important to maximize each woman's chances of conceiving a child."

Eggs of adolescent girls are different from those of adult women

Eggs of adolescent girls are different from those of adult women

Are the eggs produced by adolescent girls the same as the ones produced by adult women? A recent study published in Human Molecular Genetics by Professor Kui Liu from the University of Gothenburg in Sweden shows compelling evidence that there are two completely distinct types of eggs in the mammalian ovary - "the first wave" and "the adult wave".

Professor Liu's team used two genetically modified mouse models to show that the first wave of eggs, which starts immediately after birth, contributes to the onset of puberty and provides fertilizable eggs into the transition from adolescence to adulthood. In contrast, the adult wave remains in a state of dormancy until activated during the adult life and then provides eggs throughout the entire reproductive lifespan.

This is the first time that the developmental dynamics of two distinct populations of eggs have been clearly described in an animal model, and there is evidence that these two waves of eggs most likely also exist in the human ovary. The identification and characterization of the two waves of eggs will lead to new ways of thinking about how to obtain the best eggs when treating women for ovarian diseases that cause infertility. Such techniques will prove especially useful for women suffering from premature ovarian failure (POF), which affects 1%-4% of all women of childbearing age. The results may also lead to more effective treatments for ovarian diseases by specifically targeting the different egg populations.

Dr. Liu is a professor at the Department of Chemistry and Molecular Biology, University of Gothenburg. His research group specializes in the development of female germ cells. His work in recent years has focused on translating the results from animal models into clinical techniques for treating female infertility.