June 20, 2008 -- One in 100 U.S. babies was conceived in a test tube -- and
half these babies were twins, triplets, or higher multiple births, the CDC
The CDC's most recent data on in vitro fertilization or IVF covers the year
2005. The data come from 422 of the 475 U.S. medical centers that provide
various forms of assisted reproduction technology to people with fertility problems.
The findings highlight a
major issue for IVF: multiple births. Because IVF is expensive, and in 2005
had only a 35% chance of resulting in a live birth, doctors most often implant
multiple embryos into a woman's womb. The result: In 2005, 49% of IVF babies
came in multiple births.
While IVF led to 1% of births in 2005, it accounted for 16% of twins and 38%
of triplets or higher multiples. That's a $1 billion health problem, the CDC
calculates, because twins and higher multiples are at high risk of being born
Preterm babies have more health problems than do full-term infants, and IVF
babies are more than three times more likely to be preemies.
"Approximately 42% of assisted-reproduction-technology infants born in
2005 were preterm, compared with approximately 13% of preterm births in the
general U.S. population," the CDC's Victoria Clay Wright, MPH, and
colleagues note in their report.
Currently, there is a trend among fertility specialists to encourage
single-embryo procedures. Wright and colleagues argue that these efforts to
limit the number of embryos transferred in each procedure "should be
continued and strengthened."
Single-embryo transfers in women under age 35 had a 43% chance of resulting
in a live birth. That's only 10% less than the 53% live-birth rate for
"The 10% increase in the live-birth rate was accompanied by a 41%
increase in the risk for a multiple delivery," Wright and colleagues
observe. They suggest that IVF success should be measured not only by whether
the technique resulted in a live birth, but by whether the technique resulted
in a singleton birth.
Fertility, Infertility, and In Vitro Fertilization
The report carries a number of other eyebrow-raising findings:
42% of IVF procedures result in a pregnancy; 35% result in a live birth.
The highest live-birth rate -- 52% -- comes from IVF procedures using
freshly fertilized embryos from donor eggs.
The lowest live-birth rate -- 28% -- comes from IVF procedures using the
patient's eggs and thawed embryos.
Low birth weight was seen in 9% of IVF single births, 57% of IVF
twins, and 95% of IVF triplets or higher multiples.
Premature birth occurred in 15% of IVF single births, 66% of IVF twins, and
97% of IVF triplets or higher multiples.
11% of medical centers performing IVF procedures did not report data to the
CDC as required by federal law.