Fertility specialists know IVF success is more likely in younger women, a situation often attributed to the age of the egg. A new study, however, indicates it may not be the egg but the egg’s environment that influences success. The research team found that a slight alteration in the standard IVF procedure could boost success rates for many older women.
A live birth is the measure of IVF success and the number of births per cycle has been improving steadily as medical advances develop but the rate continues to drop dramatically in correlation to the woman’s age. Recent data indicates success rates for older women are:
- 23.6% for women aged 38 and 39
- 1.3% for women 44 and older
Dr. Yan-Guang Wu and his research team at The Center for Human Reproduction in New York City found the timing of egg retrieval is a key to success when treating older women and that the natural hormonal fluctuations of the menstrual cycle help establish the best time for retrieval.
During a menstrual cycle, hormonal changes at the time of ovulation include:
- Follicle-stimulating hormone (FSH) — spikes to encourage egg maturity.
- Luteinizing hormone (LH) — triggers the release of a mature egg (ovulation).
- Estrogen — spikes slightly and then drops and maintains its lowest level until after menstruation.
- Progesterone — rises gradually but significantly after ovulation to prepare the uterus for possible pregnancy.
During a typical IVF cycle, egg size is measured for maturity and when eggs reach 19 to 21 millimeters (mm), the patient receives an injection of human chorionic gonadotrophin (hCG), a hormone that ripens eggs for harvesting.
Until eggs reach maturity, they are cradled by granulosa cells within the ovary. Granulosa cells have receptors for FSH and LH. The researchers discovered fewer FSH receptors in the granulosa cells of older women and more LH receptors, a factor that could trigger premature luteinization, a condition that would halt both egg maturity and uterine preparation for pregnancy.
The researchers tried administering hCG earlier than usual, when eggs were only 16mm in size, with the hope that harvesting them before luteinization begins would increase odds of success.
The 16mm eggs were more immature than usual at harvest but, in many cases, fertilization did occur, embryo development and implantation progressed as hoped, and the overall success rate of IVF in older women undergoing regular treatment increased admirably.
Wu described his study as a demonstration that the eggs’ environment is more responsible for poor IVF success than the age of the eggs themselves. “The chances of reversing damage to an egg (caused by premature luteinization) are practically zero,” he said but “it’s much more hopeful to therapeutically target the egg’s supporting environment” to achieve the best odds for IVF success in older women.
- Wu, Yan-Guang, et al. "Aging-related premature luteinization of granulosa cells is avoided by early oocyte retrieval." Journal of Endocrinology 226.3 (2015): 167-80. Web. 25 Aug. 2015.
- Wu, Yan-Guang. "Retrieving eggs earlier in fertility treatment may improve IVF success rates for older women." AlphaGalileo. Society for Endocrinology, 10 Aug. 2015. Web. 25 Aug. 2015.