Women aged 43 and above could improve their chances of getting pregnant by means of in vitro fertilization (IVF) if they allow egg retrieval at an earlier stage of their menstrual cycle, according to a new study.

"We used to think that aging eggs were responsible for poor IVF success rates in older women, but here we show that it is more due to the aging of the egg's environment," said Dr Yanguang Wu, Embyrologist and Associate Scientist at the Centre for Reproductive Medicine in New York.

Mechanisms that nourish and support the eggs decline rapidly after a woman turns 43, according to the U.S.-based research team, which leaves the eggs exposed to potentially damaging hormones.

In the study, the team found that retrieving eggs from smaller follicles early on in the IVF procedure minimizes exposure to hormones, leading to higher-quality embryos and improved pregnancy rates.

The goal of the study, which was published in the Journal of Endocrinology, was to examine the dire statistics for older women trying to conceive using IVF technologies.

Women over age 44 have a 1.3 per cent chance at conceiving through IVF, yet for those between the ages of 38 and 39, chances are 23.6 per cent.

Comparing the reproductive tissue of egg donors in their 20s against those aged 30 to 37 and also against infertile patients between 43 and 47, the team found that the supportive cells -- called granulosa cells -- were sparse in the oldest age bracket.

Older women's granulosa cells produce fewer cell receptors for follicle-stimulating hormone (FSH), which regulates the cycle, yet their production of cell receptors for ovulation-inducing luteinizing hormone (LH) spikes, according to the study.

This means that the once-supportive granulosa cells of mature women could interrupt the egg development process in the ovaries and also the preparation of the uterus for pregnancy.

A false start significantly decreases the odds of conception, according to the researchers.

Normally, doctors wait until a woman's follicles expand to a significant size before injecting hormones intended to ripen the eggs inside them, yet the team tried a different approach.

They administered the ripening hormone -- human chorionic gonadotropin (hCG) -- early on when the follicles were just 16mm, instead of the 19 to 21mm that is standard in conventional IVF.

Indeed, the eggs harvested using this strategy were less mature than those extracted by the conventional method, yet they produced a higher number of quality embryos and higher pregnancy rates when compared to conventional IVF technologies.