MUNICH – Women who hyperrespond to ovarian stimulation have an increased risk for obstetric complication of a pregnancy started during the same oocyte retrieval cycle, based on data from more than 40,000 women who underwent assisted reproduction during 2001-2008.
A retrospective review of 28,275 singleton pregnancies that followed in vitro fertilization or intracytoplasmic sperm injection found that hyperresponsive women, defined as those producing more than 15 oocytes following ovarian stimulation, had a relative 9% increased risk for having a low-birth-weight baby and a 10% relative increased rate of preterm birth, compared with women who produced a normal oocyte number, 4-15, Dr. Sesh K. Sunkara said at the annual meeting of the European Society of Human Reproduction and Embryology. These differences were statistically significant.
Mitchel L. Zoler/Frontline Medical News
Dr. Sesh K. Sunkara
Other significant correlates of an increased risk for low birth weight and preterm birth were age, presence of an ovulatory disorder, and presence of a tubular disorder, said Dr. Sunkara, an obstetrician at Royal Marsden Hospital in London. After establishing these risk factors in this derivation cohort of more than 28,000 women, Dr. Sunkara and her associates tested the relationships with data collected from an additional 12,118 women drawn from the same U.K. registry during 2001-2008 and found identical relationships.
The findings highlight the importance of using ovarian stimulation methods that avoid hyperstimulation and hyperresponse, Dr. Sunkara said. In addition, future research should explore the physiologic processes that underlie the increased obstetric risk seen in the oocyte hyperresponders.
The study used data collected by the U.K. Human Fertilization and Embryology Authority. The overall live birth rate among the 28,275 women in the derivation cohort was 23%. The rate of preterm birth (less than 37 weeks’ gestation) and low-birth-weight babies (less than 2500 g) was 10% for each category. The rate of extreme preterm birth (less than 32 weeks) and the rate of extreme low birth weight (less than 1500 g) was 2% for each category.
The rate of extreme low birth rate was increased by a relative 16% among the hyperresponsive women, compared with those who produced 4-15 oocytes. The rate of extreme preterm birth increased by a relative 32%, compared with normally responsive women. Women with a poor response to ovarian stimulation, producing three or fewer oocytes, had similar rates of obstetric complications as normally responding women.
The analysis showed the highest combined rate of low birth weight plus preterm birth as 19% of all births in women younger than age 34 with hyperresponse to stimulation and both ovulatory and tubular disorders. In contrast, women aged 38 or older with a poor response to ovarian stimulation and neither an ovulatory nor a tubal disorder had a 10% combined rate of low-birth-weight and preterm birth pregnancies.
Dr. Sunkara had no disclosures.
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