Most Americans think two children is the ideal number to complete a family, so it’s no surprise that many fertility patients hope that IVF can deliver all the children we want in a single retrieval cycle. In this month's Fertility and Sterility, the team from Boston IVF estimated that nearly a quarter of patients are “one-and-done” candidates – they’ll have two pregnancies and live births from one IVF egg retrieval. Those most likely to qualify are younger, healthier, and produced more eggs in the first cycle.
The group looked at approximately 2,000 patients who had completed an egg retrieval and then used only those fresh or frozen embryos. Since a fair number of patients had not yet returned back to use their frozen embryos, the Boston IVF group had to make a few assumptions on future rates of use and success.
The group determined about 22% of patients were likely to have two or more children from the eggs retrieved in that first cycle. A key determinant was the number of eggs retrieved. Below are actual success rates by the number of eggs retrieved. This doesn’t contemplate those patients with stored embryos who could still return to use them and that’s why the numbers below don’t average out to the 22% figure.
The number of eggs a woman produces is a function of her own underlying fertility and the hormone regimen she is proscribed. On the first count, younger women and those with a lower Body Mass Index were far more likely to produce more eggs and ultimately be “one-and-done” candidates.
When it comes to treatment regimen, clinicians can clearly push the dosage of hormones to yield more eggs. The risk is the doctor overstimulates the woman’s ovaries and dramatically raises her risk of OHSS. For instance, when a woman produces 16 – 20 eggs she is four-times more likely to develop OHSS than a similar woman who produces 6 – 10 eggs. Study investigators were quick to point out that 2% of patients developed OHSS and only 3 of those were hospitalized .
The results of the study are intriguing because for a non-insignificant minority, they had the chance to complete their family goals without absorbing the additional medical, financial and emotional trauma associated with future retrieval cycles. That said, the study has its limitations in that it was conducted at a single center, so it may not be generalizable, and was short enough in duration to require a prediction model to compensate for the fact many patients hadn’t yet returned to use their extras embryos.