The number of eggs needed to be retreived for IVF will largely depend on the quality of the eggs retrieved but the average number of eggs retrieved per cycle is between 10 to 14 eggs. The number of good quality eggs retrieved from the ovaries will influence the number of embryos suitable for successful transfer/implantation and subsequently achieving a successful birth.
How many eggs should be retrieved to have the best chance of a successful live birth?
In a 2011 UK study, researchers analyzed more than 400,000 IVF cycles done in the UK from 1991 to 2008 and found the rate of live births increased as the number of eggs increased to 15, plateaued between 15 and 20 eggs and steadily declined beyond 20 eggs. These results were reflective of a younger patient population (more than half were ages between 18 to 34 years) and the IVF cycles were done with fresh eggs retrieved from the patient.
The same study also created a chart using the data analyzed to predict live birth rates based on the age group and the number of eggs retrieved as shown below.
Image: Sunkara SK, et al.
As one can see, the predicted live birth rate peaked around 15 to 20 eggs in all the four age groups. The chart shows the predicted live birth rate decreasing as the age of the women increases, even when the number of eggs retrieved increased. Retrieving 15 eggs at the age of 40 years and over had similar predicted live birth rate as retrieving 2 eggs at the ages of 18 to 34 years. This shows the general decline in the fertility and the increasing difficulty of becoming pregnant as women ages.
In a 2013 Chinese study, researchers analyzed 2,455 women who undergone their first IVF treatment cycle from 2007 to 2011 and found the cohort that collected between 6 and 15 eggs had the best rates of live births. Like the 2011 UK study, this study is reflective of a younger patient population (study only analyzed women aged between 18 and 34 years) and the IVF cycles were done with fresh eggs retrieved from the patient.
So does this mean every woman undergoing IVF should be stimulated toward the retrieval of about 15 eggs?
A woman’s age is a strong predictor in the number of eggs retrieved after ovarian hyperstimulation. This is due to the natural decline in the woman’s ovarian reserve as the woman ages. For example, women over 40 years with maximal ovarian stimulation would have great difficulty producing 15 eggs, whereas a young woman with polycystic ovarian syndrome (PCOS) will often exceed this number, even with the mildest stimulation.
Giving higher doses of reproductive hormones during ovarian hyperstimulation to boost the number of eggs retrievable increases the risk for ovarian hyperstimulation syndrome (OHSS), increases the risk for possibility harming the endometrium, and may negatively affect the egg quality. As seen in the chart above, a 40-year-old woman with 15 eggs only has a predicted live birth rate of about 15%. The risk of adverse effects from maximizing the hormone doses in a 40-year-old woman to try to retrieve 15 eggs often outweighs the benefit of increased egg retrieval.
The goal of the fertility doctor is not solely focused on the number of eggs retrieved, but trying to retrieve “enough eggs” to have a successful birth. A clinician and the patient will need to balance the risks and benefits of aggressively stimulating the ovaries to maximize egg production to improve the success rate of a live birth. For a woman with normal ovarian function and less than 35 years of age, retrieving 15 eggs looks to be the magic number for the best chance of having a baby through IVF. For women who are older or have a complicated case, the number needed to retrieve will be individualized to their specific case.
Vaughan DA, Leung A, Resetkova N, et al. How many oocytes are optimal to achieve multiple live births with one stimulation cycle? The one-and-done approach. Fertil Steril. 2017; 107: 397-404.
Sunkara SK, Rittenberg V, Raine-Fenning N, Bhattacharya S, Zamora J, Coomaeasamy A. Association between the number of eggs and live birth in IVF treatment an analysis of 400,135 treatment cycles. Hum Reprod. 2011; 26: 1768–1774.
Ji J, Liu Y, Tong XH, Luo L, Ma J, Chen Z. The optimum number of oocytes in IVF treatment: an analysis of 2455 cycles in China. Hum Reprod. 2013; 28: 2728-2734.