# When to Choose In Vitro Fertilization (IVF) When Postponing Conceiving: The Age‐Related Risk of IVF Failure at an Advanced Age

## TL;DR

This study identifies age 35 as a key threshold for IVF success, showing that the risk of failure increases rapidly after this age.

## Contribution

The study provides a validated age reference for IVF success rates and identifies a specific inflection point at age 35.5.

## Key findings

- Age 35.5 is identified as the inflection point where IVF success rates begin to decline significantly.
- The live birth rate does not vary with age for women 35 and younger.
- The risk of IVF failure increases rapidly between ages 35–37 and 37–40.

## Abstract

To validate previous age subgrouping methods and provide an optimal age reference for women planning to delay in vitro fertilization (IVF).

From July 2014 to March 2018, 3012 patients that received IVF/intracytoplasmic sperm injection (ICSI) were continuously recruited in this retrospective, single‐center study. We analyzed the relationships of baseline characteristics and IVF outcomes. A smooth fitting curve depicting the association of age and live birth was plotted using the generalized additive model (GAM) method. We also evaluated the association of age and live birth among different age groups (> 20, ≤ 35; > 35, ≤ 37; > 37, ≤ 40; and > 40).

Age, duration of infertility, and baseline follicle‐stimulating hormone (FSH) were significantly related to the live birth rate. The adjusted Odd Ratio (OR) value of age was 0.95 (P < 0.001), indicating the higher occurrence of no live birth with age increasing. The fitting curve showed that the live birth rate decreased with age. And 35.5 (34.5–36.5) was identified as the inflection point of the curve. The slopes before 35.5 and after 35.5 were significantly different (0.9 [0.9, 1.0], P < 0.001). When ≤ 35, live birth rate did not vary with age. For the ages of 35–37 and 37–40, the occurrence of negative outcome increased with age (aOR: 0.73 [0.53, 0.99], 0.80 [0.65, 1.00]; P = 0.0441, 0.0465, respectively).

The age of 35 can be referred to as the safe time point when the IVF success rate does not decline with age. And the risk of IVF failure increases rapidly in the period of 35–37 and 37–40.