It is an established fact that risks associated with giving birth to babies conceived through IVF, are increased for both mothers and infants. Most of that increase in risk is related to the higher occurrence of multiple births. Currently, more than 30% of IVF pregnancies are twin or higher-order multiple gestations.
The Center for Disease Control (CDC) lists the following statistics concerning adverse outcomes associated with twin pregnancies, regardless of whether or not IVF is used:
Twin babies are nearly 6 times as likely to be born premature.
Twin babies are more than 5 times as likely to be admitted to a neonatal intensive care unit.
Twin babies are more than 4 times as likely to have cerebral palsy.
Twin babies are more likely to be stillborn, have birth defects or develop autism than single babies.
Women carrying twins are twice as likely to develop pregnancy-related high blood pressure.
Women carrying twins are one and a half times more likely to develop gestational diabetes.
In light of these facts, the American Society for Reproductive Medicine (ASRM) and the Society for Assisted Reproductive Technologies (SART), have established guidelines for the maximum number of embryos to be transferred in an IVF cycle in order to reduce the number of multiple gestations. They encourage single embryo transfer for patients who have the most favorable indicators for success, which include age less than 38, first IVF cycle, good quality embryos, and with more than one embryo available for transfer.
The CDC tracks success rates for women who receive IVF and from 2010 to 2012, they found that transferring one embryo at a time can lead to a better chance of having at least one baby while reducing the chance of having twins. For example, when a fresh embryo was transferred 5-6 days after retrieval, 51% of women had at least one baby, but the incidence of twins was only 1%. If your fresh transfer is not successful in achieving pregnancy, you can freeze extra embryos and then begin a frozen embryo transfer (FET) cycle with your next menses. The CDC shows that when a fresh embryo is transferred and then a frozen embryo is transferred later, 66% of women had at least one baby, and again the risk of having twins was only 1%. This compares to transferring two fresh embryos in which 60% of women had at least one baby, but the risk of having twins was a whopping 27%!
This research demonstrates that the best way to reduce the chance of having twins from an IVF cycle is to reduce the number of embryos transferred. Given the very serious complications associated with twin pregnancies, this is also the best way to help ensure a healthy pregnancy for the mother and the birth of a healthy baby.
Janet Chiaramonte joined the staff of Invia Fertility as a registered nurse in 2005. Years ago (too many to count), she received her Bachelor's Degree in Psychology, and then worked for a decade at Children's Memorial Hospital in an administrative position. She always wanted to be part of the patient care side of medicine though, so she went back to school and received an Associate's Degree in Nursing.