Fertility treatment pregnancy rates increase significantly and miscarriages are reduced if eggs that consume oxygen in a stable manner are used for in vitro fertilization, joint research by a clinic and two universities has found.
In fertility treatment, doctors decide which fertilized eggs are best for use by judging the shape and condition of the eggs using a microscope. However, this method lacks precision as it relies only on physical observations, and the rate of pregnancy using such eggs for the procedures is only 20 percent to 30 percent. Patients are often required to endure the in vitro fertilization process several times before a pregnancy occurs.
However, fertilized eggs also consume oxygen, and Takafumi Utsunomiya, director of St. Luke Clinic in Oita, measured the amount of oxygen eggs breathe by measuring subtle changes in oxygen concentration in a culture solution surrounding the egg. The technique was developed by Tohoku University and Yamagata University.
Utsunomiya and the universities compared over a two-year period the treatment results of two groups whose eggs appeared in good condition--21 women whose eggs were chosen only through visual observation and 20 women whose eggs were chosen through visual observation and measurement of oxygen consumption. The visual-observation-only group's pregnancy rate was 38 percent, while the other group's was 60 percent. The miscarriage rate was 25 percent for the first group and 8 percent for the latter.
The Japan Society of Obstetrics and Gynecology limits the number of fertilized eggs that can be returned to the womb to only one, in an attempt to reduce the risk of multiple pregnancies. The move has pressured obstetricians to develop techniques that can better select eggs that are in good condition.
"There's big difference in 'breathing' levels even among eggs that appear in good condition," Utsunomiya said. "We'll work to promote further research at more facilities."
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