Don't put all your eggs in one basket.
It's
advice that couples tend to ignore when talking to their fertility
doctor about the number of embryos to transfer during IVF. Because the
cost of fertility treatment is high and is usually not covered by
insurance, they hedge their bets and gamble that transferring multiple
embryos will increase the chances of getting pregnant. And while
stricter guidelines for embryo transfer have been successful at reducing
higher order multiples (triplets or more), "the next hurdle is how do
we reduce the twin rate while maintaining the same pregnancy rate?" says
R. Stan Williams, MD, president of the Society for Assisted
Reproductive Technologies (SART), and professor and chair of the
Department of OB-GYN at the University of Florida.
Patients,
however, tend to not see the risks of being pregnant with two. Michael
A. Feinman, MD, Medical Director of HRC Fertility in Southern
California, says some couples strongly want to transfer two embryos or
actually desire twins. "Some couples think twins are 'cute,' because
they do not see the ones who experience the problems of prematurity or
see how difficult it is for parents to handle them."
The Risks of Multiples
Fertility
doctors and patient advocates are working to educate patients about the
serious health risks and high costs of having more than one baby at the
same time.
"We have to do a better job educating patients about
the health risks - they are not getting these messages," says Barbara
Collura, executive director of the infertility patient advocacy group
RESOLVE. "They are being told it by their doctor as part of the informed
consent process. But reproductive endocrinologists - you can ask any
single one of them if they ever get pressure from the patients to
transfer more than the required guidelines state, and they will tell you
'yes, every day.'"
Even though there seem to be twins everywhere
these days (between 1980 and 2004, the rate of multiple births increased
by 70 percent), the risks to the health and well-being of the mother
and babies - and the costs to society - are quite high.
"It has
been shown that twin pregnancies cost society billions of dollars each
year," Dr. Feinman says. "These costs are due to increased maternal
hospitalizations to prevent prematurity, increased intensive care for
the babies from prematurity, and increased rates of lifelong
disabilities like cerebral palsy in twins."
Women who are pregnant with twins are at much higher risk for pregnancy complications, including:
- Premature birth: About 60 percent of twins are born prematurely at an average of 35 weeks.
- Low birthweight: More than half of twins are born at less than 5 ½ pounds. Low birthweight babies, especially those born before 32 weeks and/or weighing less than 3 1/3 pounds, are at increased risk of health problems during the newborn period, as well as lasting disabilities such as mental retardation, cerebral palsy, and vision and hearing loss.
- Cesarean section: Women who carry multiples may be more likely to need Caesarean sections, which may require a longer period of recovery and at times can increase the risk of hemorrhage during and after delivery.
- Twin-Twin Transfusion Syndrome (TTTS): About 10 percent of identical twins who share a placenta develop TTTS, which occurs when a connection between the two babies' blood vessels in the placenta causes one baby to get too much blood flow and the other too little.
- Pre-eclampsia: Women expecting twins are more than twice as likely to develop pre-eclampsia, which is a combination of high blood pressure, protein in the urine and generalized swelling that can be dangerous for mother and baby.
- Gestational diabetes: This pregnancy-related form of diabetes can cause the baby to grow especially large, increasing the risk of injuries to mother and baby during vaginal birth. Babies may also have breathing and other problems during the newborn period.
Single Pregnancy Is Safer
Being
pregnant with one child is safer, with the greatest chances for an
optimal outcome. A recent study published in BMJ (British Medical
Journal) found that women who undergo IVF are almost five times more
likely to give birth to a single healthy baby following a single embryo
transfer (SET) when compared with women who choose to have two embryos
transferred. In addition, the SET appeared to significantly increase the
chances of carrying the baby to full term (37 weeks).
With
medical advances, assisted reproductive technology (ART) has come a long
way from the early days of transferring six embryos in the hopes of
getting just one to implant. Newer techniques such as blastocyst stage
culture and transfer are maximizing pregnancy rates and minimizing the
risk of a multiple pregnancy. By growing embryos for five days in the
laboratory and enabling them to reach the blastocyst stage of
development, fertility doctors can better determine which embryos have
the greatest likelihood of implantation.
Research has shown that
success rates for single embryo transfer vs. double embryo transfer are
similar in certain circumstances. "In a favorable patient who is having a
blastocyst (Day 5 embryo) transfer, one blastocyst is an equivalent
pregnancy rate to two," Dr. Williams says.
But some couples have
difficulty accepting these studies, according to Dr. Feinman. "They
intuitively feel that the second embryo must hedge their bet. Also,
input from friends and former patients often affects their feelings."
The
most recent 2009 guidelines on embryo transfer from the American
Society for Reproductive Medicine (ASRM) and SART are very
individualized. For example, for a woman under age 35 who is in the
favorable category, the recommendation is to transfer one embryo if it
is a Day 5 (blastocyst), and one to two embryos if it is a Day 3.
"The
big advantage of the American system is we can look at shades of gray,"
Dr. Williams explains. "Depending on the patient's age, the prognosis
of the patient, and the stage of the embryo development, we can develop
guidelines that are more flexible to meet the needs of the patient while
trying to reduce the potential for multiples."
