Does freezing of embryos improve live birth rates in women of advanced reproductive age?

This study investigated live birth rates (LBRs) in women that underwent frozen (Fz) embryo transfer (ET). 

They found that LBRs were higher with Fz-ET in women under 35, but there was no difference between Fz and fresh (Fr) ET in those older than 35.

Infertility is a common condition. Assisted reproductive technology (ART) has greatly improved outcomes for infertile people. There are a number of procedures available to couples. In vitro fertilization (IVF) is one option. Intracytoplasmic sperm injection (ICSI) is another option. After IVF or ICSI embryos must be transferred to the uterus. This can be done straight away. This is called a fresh embryo transfer (Fr-ET). Alteratively embryos can be frozen. This means embryos can be transferred at a more suitable time (Fz-ET).

Fz-ET has become more popular for this reason. Fz-ET allows the best quality embryos to be transferred when the uterus is more prepared. It also reduces the risk of ovarian hyperstimulation syndrome (OHSS). Many clinicians recommend freezing all embryos after IVF/ICSI. It is unclear if women's age affects fertility outcomes with Fz-ET.  

This study included 1882 embryo transfers. There were 1412 Fr-ETs and 470 Fz-ETs. The authors grouped patients according to age. Under 35, 35-38 and over 38 were the age groups. Fertility outcomes such as clinical pregnancy rate (CPR), live birth rate (LBR), and pregnancy loss (PL) were compared between Fr-ET and Fz-ET. 

A significantly higher LBR was associated with Fz-ET (43.7%) compared to Fr-ET (24.5%) in women under 35. The chance of live birth was 2.46 times higher in this age group with Fz-ET. There was no difference in LBR in the other age groups. CPR was higher in all age groups with Fz-ET. PL was lower in the under 35 group with Fz-ET. 

The authors concluded that LBRs were higher with Fz-ET in women under 35.

This study was based on medical records. Some information on fertility was not available. This included endometrial (uterine lining) thickness and ovarian reserve. These factors could also influence fertility outcomes. More controlled studies are needed. 

If you have any concerns regarding infertility management please consult with your doctor.