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For ‘in vitro’, 15 is the perfect number

By Dr Sesh Kamal Sunkara


In vitro fertilization (IVF) involves the retrieval of an egg and fertilization with sperm in the laboratory (in vitro) as opposed to the process happening within the human body (in vivo), with a natural conception. IVF was first introduced to overcome tubal factor infertility but has since been used to alleviate all types of infertility and nearly four million babies have been born worldwide as a result of assisted reproductive technology.

The birth of Louise Brown in 1978, the world’s first IVF baby was from a natural menstrual cycle without the use of any stimulation drugs. As success rates were low with natural cycles in the early days of IVF, ovarian stimulation regimens were introduced into IVF to maximize success rates. The aim was to retrieve more eggs to overcome the attrition in numbers at fertilization, cleavage, and implantation. However, with the introduction of ovarian stimulation regimens the complication of ovarian hyperstimulation syndrome (OHSS) arose.

There have been several discussions among IVF clinicians on what the ideal number of eggs should be to optimize IVF outcome and minimize risk of OHSS. We analysed a large database of over 400, 000 cycles provided by the Human Fertilisation and Embryology Authority (HFEA) in order to establish the association between egg number and live birth rate in IVF.

We found that live birth rate increased with increasing number of eggs retrieved up to 15 eggs and plateaued from 15 to 20 eggs with a decline in live birth rate beyond 20. The analysis of the data suggested that around 15 eggs may be the optimal number to aim for in a fresh IVF cycle in order to maximize treatment success whilst minimizing the risk of OHSS. We also established a nomogram which is the first of its kind that allows prediction of live birth for a given egg number and female age group. This is potentially valuable for patients and clinicians in planning IVF treatment protocols and counselling regarding the prognosis for a live birth occurrence, especially in women with either predicted or a previous poor ovarian response.

The full paper and supplementary data has been made publicly available here, as published in Human Reproduction by Sesh Kamal Sunkara, Vivian Rittenberg, Nick Raine-Fenning, Siladitya Bhattacharya, Javier Zamora and Arri Coomarasamy. Above table appears with full permission from Human Reproduction and Oxford Journals.

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Recent Comments

  1. Alison Bagshawe

    This is a very helpful piece of research, indicating how the live birth rate varies with the number of eggs produced. It is very interesting to see how it plateaus and then falls with numbers greater than 15. It would be interesting to know whether the same pattern holds with donor eggs from younger altruistic donors providing eggs for older recipients.

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