Fewer embryos per cycle are being transferred in favor of increased use of single cell embryo transfer, leading to further reductions in the percentage of twins and high-order multiple births, according to the latest data on the use of assisted reproductive technologies in the United States.
The data come from the Society for Assisted Reproductive Technology’s 2010 IVF Success Rate National Summary, a yearly report that has been generated since 2003.
For 2010, 370 clinics reported data to SART on 146,693 treatment cycles leading to the birth of 58,727 babies. The percentage of cycles resulting in live births among women younger than age 35 years was 41.7%, compared with 31.9% for those aged 35-37 years, 22.1% for those aged 38-40, 12.5% for those aged 41-42, and 4.1% for those older than age 42. Corresponding live birth rates from the 2003 IVF Success Rate National Summary were 37.5% for women younger than age 35, 30.4% for those aged 35-37, 20.2% for those aged 38-40, 11.2% for those aged 41-42, and 4.5% for those older than age 42.
According to the 2010 report, the average number of embryos transferred per cycle was 2.0 for women younger than age 35 years, 2.2 for those aged 35-37, 2.6 for those aged 38-40, 3.0 for those aged 41-42, and 3.1 for those older than age 42. In 2003, the corresponding average number of embryos transferred per cycle was 2.6 for women younger than age 35 years, 2.9 for those aged 35-37, 3.2 for those aged 38-40, 3.5 for those aged 41-42, and 3.5 for those older than age 42.
A striking increase in the use of elective single cell embryo transfer (eSET) has occurred since 2003. In that year, the percentage of cycles with elective single embryo transfer was only 0.7% for women younger than age 35 years, 0.4% for those aged 35-37 years, 0.2% for those aged 38-40, 0.1% for those aged 41-42, and 0.0% for those older than age 42. In 2010, percentage of cycles with elective single embryo transfer was 9.6% for women younger than age 35 years, 5.3% for those aged 35-37 years, 1.7% for those aged 38-40, 0.6% for those aged 41-42, and 0.5% for those older than age 42.
The percentage of live births with twins has decreased only slightly over time, but only in the three youngest age categories. In 2003, those rates were 33.5% for women younger than age 35 years, 27.9% for those aged 35-37 years, 22.7% for those aged 38-40, 14.8% for those aged 41-42, and 7.3% for those older than age 42. By 2010 the percentage of live births with twins was 32.4% for women younger than age 35, 27.2% for those aged 35-37, and 22.1% for those aged 38-40, yet had increased to 16.9% for those aged 41-42 and 9.6% for those older than age 42.
In the meantime, the percentage of live births with triplets or more has decreased sharply. In 2003, those rates were 6.4% for women younger than age 35 years, 6.1 % for those aged 35-37 years, 5.6% for those aged 38-40, 2.8% for those aged 41-42, and 0.6% for those older than age 42. By 2010 the percentage of live births with triplets or more had fallen to 1.5% for women younger than age 35 years, 1.5% for those aged 35-37 years, 1.1% for those aged 38-40, 1.1% for those aged 41-42, and 0.9% for those older than age 42.
SART sponsored the national study.