What is the effect of age on live birth rates after one or multiple in vitro fertilizations?

This study investigated the effect of age on the live birth rate (LBR) after one or multiple in vitro fertilization (IVF) procedures. 

They found that LBR increases after more IVF cycles in patients younger than 40 years. 

In vitro fertilization (IVF) is the most common method of assisted reproduction (AR). Couples with infertility may undergo IVF to become pregnant. The primary outcome of IVF is the live birth rate (LBR). There are multiple steps in IVF. Women will take hormones to stimulate the release of eggs. Eggs are harvested and fertilized in a laboratory. The fertilized embryos are then transferred to the uterus. 

Many studies show that LBR after IVF decreases with advancing age. Many couples undergo multiple IVF cycles to achieve a pregnancy. It is unclear if the chance of live birth increases with more IVF cycles. It is also unclear if age can affect LBR after repeated IVF cycles.

This study included 547 women undergoing IVF. All women underwent controlled ovarian stimulation (COS). Fresh embryo transfer (Fr-ET) was performed in all cycles. The main outcome was LBR per cycle. 

The overall LBR after 1 IVF cycle was 33%. After 3 cycles the total LBR increased to 56.9% and to 67.9% after 6 cycles.

In women under 35 years, after 6 cycles the total LBR was 69.9%. The total was LBR after 6 cycles was 83.7% in women aged 36-39. However, the total LBR peaked after cycle 4 in women over 40 at 21.9%. 

The authors concluded that LBR increases with multiple IVF cycles in women under 40.

The cause of infertility varied greatly. It is unclear if this could also affect the LBR. The same ovarian stimulation protocol was not used in all cycles. This could have influenced the LBR. More studies are needed.