Birth Rates and Statistical Probabilities

 

Applying Probability to Birth Rates

This section examines cycle probabilities using the overall 2008 CFAS report (live birth rates for deliveries in 2007). Keep in mind that a previous result does not change the odds of a next result. Moreover, individual risk factors and circumstances differ from patient to patient.

There are many factors that influence cycle rates that are not considered on this page, such as the cause of infertility, quality and number of eggs, treatment protocols and possible protocol changes in subsequent cycles, quality of semen, age of the woman, performance of clinic, environmental factors, health, unexplained variations, etc. This exercise cannot predict the success of any individual case.

The overall live birth rate was 27%. 70% of births were singletons and 95% of the multiple births were twins.

What were the delivery rates per cycle?

Singleton 18.9%
Twins 7.70%
Triplets or more .4%

Based on the live birth rate, what is the probability of one birth over three cycles?

61.1%

For women under 35 years old, the live birth rate was 34%

What were the delivery rates per cycle?

Singleton 23.8%
Twins 9.69%
Triplets or more .51%

Based on the live birth rate, what is the probability of one birth over three cycles?

71.3%

For women aged 35-39 years, the live birth rate was 26%

What were the delivery rates per cycle?

Singleton 18.2%
Twins 7.41%
Triplets or more .39%

Based on the live birth rate, what is the probability of one birth over three cycles?

59.5%

For women 40 years old and over, the live birth rate was 11%.

What were the delivery rates per cycle?

Singleton 7.7%
Twins 3.14%
Triplets or more .16%

Based on the live birth rate, what is the probability of one birth over three cycles?

29.5%

Note: there would be substantial deviation between age 40 and mid to late 40's.

 

Combining IVF and FET Cycles - Probabilities

Assuming FET rates are 10% lower than fresh cycle rates we'll compare probabilities using one fresh cycle followed by two fet cycles. These are hypothetical numbers (not CFAS) and look at the probability of a success over three cycles. Refer to your clinic for their IVF and FET live birth rates.

IVF Live Birth Rate Success Probability Example - 1 Fresh and 2 Frozen
1st IVF 1st FET 2nd FET Live Birth
Probability
20.0% 18.0% 18.0% 46.21%
25.0% 22.5% 22.5% 54.95%
31.0% 27.9% 27.9% 67.23%
35.0% 31.5% 31.5% 69.50%
41.0% 36.9% 36.9% 76.51%

 

IUI - Clinical Pregnancy Rate Probability

This chart looks at the probability of becoming clinically pregnant after n IUI cycles. The IUI Success Rates are hypothetical (not CFAS). Refer to your clinic for their expected success rate.

IUI Pregnancy Probability Chart
IUI Success Rate 1 cycle 2 cycles 3 cycles 4 cycles 5 cycles 6 cycles
06.00% 06.00% 11.64% 16.94% 21.92% 26.60% 31.00%
07.00% 07.00% 13.51% 19.56% 25.19% 30.43% 35.30%
08.00% 08.00% 15.36% 22.13% 28.36% 34.09% 39.36%
09.00% 09.00% 17.19% 24.64% 31.42% 37.59% 43.21%
10.00% 10.00% 19.00% 27.10% 34.39% 40.95% 46.86%
11.00% 11.00% 20.79% 28.97% 36.78% 43.73% 49.92%
12.00% 12.00% 22.56% 31.85% 40.03% 47.23% 53.56%
13.00% 13.00% 24.31% 34.15% 42.71% 50.16% 56.64%
14.00% 14.00% 26.04% 36.39% 45.30% 52.96% 59.55%
15.00% 15.00% 27.75% 38.59% 47.80% 55.63% 62.29%
16.00% 16.00% 29.44% 40.73% 50.21% 58.18% 64.87%
17.00% 17.00% 31.11% 42.82% 52.54% 60.61% 67.31%
18.00% 18.00% 32.76% 44.86% 54.79% 62.93% 69.60%
19.00% 19.00% 34.39% 46.86% 56.95% 65.13% 71.76%
20.00% 20.00% 36.00% 48.80% 59.04% 67.23% 73.79%