Biological Clock and Fertility Calculator

The best reproductive years for women are in their twenties. After that, fertility declines rather rapidly, especially after age 35.

A woman’s biological clock can estimate her monthly chance of having a baby. From age 15 to age 45, there are approximately 200,000 eggs left in reserve. Within that timeframe of 30 years and given normal monthly menstruation, you have an estimated 550 available eggs per month in which only one best egg will be released.
A healthy 30 year old attempting pregnancy each month will have 18% chance of getting pregnant every month. This means that for every 100 fertile 30 year old women trying to get pregnant during one cycle, 18 will get pregnant and the other 82 will have to try again. A 40 year old woman will have 5% chance of pregnancy if she tries every month.
The diminishing quantity and quality of eggs are unbelievable, especially after age 35. Your egg quality at age 20 is that 90% are normal and 10% are abnormal. Your egg quality at age 40 is that 10% are normal and 90% are abnormal.

Egg quality is extremely important as the internal organelles of the egg are primarily responsible for creating a chromosomally normal embryo.

The Natural Process of Egg Selection – Only the Strongest Egg Survives

Each month, at the start of a new menstrual cycle, the ovaries initiate recruitment of 40 to 50 eggs from the resting oocyte (egg) pool. An elimination process begins such that by ovulation time 14 days later, only the most favorable oocyte is released each month.

Even with this rigorous selection, an oocyte can still have undetectable abnormalities, which can slip by nature’s protective screening mechanisms. These checks and balances help minimize abnormal pregnancies, insuring that only the healthiest embryos can implant.

Unsuitable eggs may fail to become fertilized or not divide properly leading to failed implantation or abortion. Unfortunately, the changes discussed above cannot be reversed and with advancing age, even IVF may not overcome the egg abnormalities. In these cases the physician may recommend the use of donor eggs to bring about a healthy pregnancy and a happy family.