Implantation Rate (IR)

Definition - What does Implantation Rate (IR) mean?

Implantation rate (IR) is the percentage of embryos transferred during an in vitro Fertilization (IVF) cycle that develop into gestational sacs (a visual indicator of pregnancy.) The IR can be calculated for an individual patient or a group of patients.

Critiques of using IR as a measure of success include that it is easy to distort data when fewer embryos a transferred. Additionally, the ideal outcome from an IVF procedure is the birth of a baby and not simply the implantation of an embryo.

FertilitySmarts explains Implantation Rate (IR)

Implantation rates are calculated by dividing the number of gestational sacs visualized by ultrasound 3-5 weeks post transfer by the number of embryos transferred. If two embryos were transferred and one gestational sac is observed, that means the IR is 50%.

The implantation rate primarily depends on the quality of embryos; poor quality embryos are the most common cause of low implantation rates.

Additionally, in a study conducted to analyze the effect of age on implantation rates, researchers found that the implantation rate decreased by 2.77% per year in their study population after the age of 35.

Most doctors use live birth rate or ongoing pregnancy rate to quantify outcomes of IVF.

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