About Statistics

Any serious discussion of IVF success demands a strict definition of terms. The term "pregnancy" can have various connotations from positive pregnancy test to live born delivery. The term “biochemical pregnancy” indicates that the embryo has implanted with a rise in the pregnancy hormone (beta hCG) level with early loss prior to visualization on ultrasound. A “clinical pregnancy” must at least progress to the point where a pregnancy sac and fetal heart activity may be documented on ultrasound. “Ongoing pregnancies” are those pregnancies which proceed toward term, minus any miscarriages.

Pregnancy rates may be expressed per IVF cycle started, per egg retrieval, or per embryo transfer procedure.

Approximately 1 in 5 IVF pregnancies is miscarried, mostly in the first twelve weeks as spontaneous miscarriage. After age 40 years, approximately one-half of all pregnancies are lost. The miscarriage rate in IVF is greater than for spontaneous conceptions in the general population.

The most frequent complication of IVF has been multiple gestation. Prior to the advent of blastocyst culture and transfer, approximately 30% of IVF pregnancies were multiple gestation of which approximately 25% were twins, 4.8% were triplets and 0.2% were quadruplets or more. With blastocyst culture and transfer of one or two blastocysts, the multiple gestation rate is approximately 25% of which 24% are twins and one percent are triplets or more.

Pregnancies with more than one baby represent an increased risk for pre-term labor and deliver and could result in poor outcome with lifelong consequences for the offspring. These risks increase as the number of fetuses in a pregnancy increases.

Babies delivered following IVF may be a slightly increased risk for congenital abnormalities or other problems compared with children who are conceived spontaneously. This risk is thought to be secondary to infertility diagnoses, including advanced reproductive age.

In general, at the Center for Reproductive Medicine, patients who are 34 years of age and younger should have an approximately 50% chance for ongoing pregnancy per blastocyst transfer and patients age 35-39 should have an approximately 30+% chance. Patients who are 40 years of age have an approximately 20% chance and this chance decreases to approximately 10% at 42 years.

For a review of CRM’s most recent statistics, as reported by the CDC, please visit the CDC website at www.cdc.gov/reproductivehealth/art.htm.