Pregnancy via Frozen Embryo Replacement Provides better Birth Outcomes than Fresh IVF

Pregnancy achieved through implantation of a frozen embryo during an in vitro fertilization (IVF) treatment can provide better birth outcomes than using a fresh one, researchers reveal.

For reaching this conclusion, Ulla-Britt Wennerholm, of Sahlgrenska University Hospital in Göteberg, Sweden and colleagues went through data of IVF treatments in Norway, Sweden and Denmark, between 1984 and 2007. They compared the details with the Nordic Medical Birth Registries. They looked at nearly 7,000 babies born via frozen embryo replacement (FER), more than 42,000 born via fresh IVF and over 288,800 babies born without the help of IVF.

Premature birth, low birth weight and small for gestational age were found more common among babies born via fresh IVF than the FER children. They also found children born via frozen embryo replacement were large for their gestational age and had a low birth weight compared to fresh IVF.

They also found birth outcomes for frozen embryo replacement poorer compared to normal pregnancies.

"FER is used increasingly in IVF programs to avoid the risks associated with multiple births,"  Wennerholm, said in a news release. "We sought to analyze the outcomes compared to spontaneous conceptions and fresh IVF."

Findings of the study will be presented February 14 at the Society for Maternal -Fetal Medicine's annual meeting, The Pregnancy Meeting, in San Francisco, California.

Various artificial methods adopted by people who experience difficulties to conceive naturally are called assisted reproductive technology or ART. In vitro fertilisation (IVF), intracytoplasmic sperm injection (ICSI), cryopreservation and intrauterine insemination (IUI) are some of the ART methods commonly used in the country. ART has been prevalent in the U.S. from 1981 and each year, over one percent of American infants are conceived through ART.

Findings of the current study confirm previous research that looked into the benefits of conceiving with frozen embryos than fresh ones.

A study presented at the British Science Festival in Sep.2012, found frozen embryos more effective in ensuring success of IVF treatment and having a smooth and trouble -free pregnancy than using fresh embryos. Two theories were put forward by the investigators to explain the factors that influenced this occurrence- only quality embryos survive freezing process and  it will give the  womb enough time to recover from the strain involved in releasing eggs during the IVF treatment.

Another study conducted by Dr. Claudino Benadiva from The Center for Advanced Reproductive Services (CARS) at the University of Connecticut Health Center and Linda Siano, chief embryologist found vitrification, a technique that is used in rapid freezing of eggs, highly promising for women who want to postpone pregnancy.