Natural Fertility and Why Age Is the Single Biggest Factor

Natural fertility is defined as the capacity to produce a child, and the single most important factor affecting it is a woman's age. Women are born with a fixed, finite number of eggs that only ever decreases: 6 to 7 million eggs at 20 weeks of gestation in the womb, down to 1 to 2 million at birth, and down further to 300,000 to 500,000 by puberty. That original supply is used throughout a woman's entire reproductive life; it is never replenished.

Why age drives the pregnancy rate

Both the number and quality of eggs decline as a woman ages, which is why fertility itself declines with age. The pregnancy rate is highest between 25 and 35 years and drops meaningfully by 40. In a regular 28-day menstrual cycle, the highest chance of pregnancy is around ovulation, since a released egg survives only 12 to 24 hours, while sperm can survive 4 to 5 days.

This article is based on a Jivo Masterclass session conducted by Dr. Parul Prakash, Head, Reproductive Medicine (IVF), Artemis Hospital, Gurugram. The article has been summarised with the assistance of an AI tool from the original masterclass recording. Watch the full Masterclass recording

Looking for a fertility or IVF consultation? Get in touch with the Jivo team