Evaluation of weight change during ovarian stimulation treatment

The number of women undergoing ovarian stimulation for either in vitro fertilization or planned oocyte cryopreservation for conception or fertility preservation has remarkably increased over the past decade. Prior to undergoing ovarian stimulation, patients are typically counseled about risks, including medication reactions, surgical risks, and anticipated number of oocytes from each cycle based on ovarian reserve testing. One possible side effect that is a common concern among patients is what amount of weight change might be expected during the treatment cycle. However, there are very limited data on how much weight can change during modern ovarian stimulation treatment cycles.

To determine the mean weight change for patients undergoing ovarian stimulation and to evaluate whether this differed in patients diagnosed with ovarian hyperstimulation syndrome and/or those undergoing multiple cycles.

Retrospective cohort study of 22,106 antagonist ovarian stimulation cycles with weight collected prior to stimulation and on the day of retrieval (n=8332) or postretrieval (n=13,774) from January 1, 2017 to December 31, 2023. Main outcome was mean weight fluctuation (kg) from baseline weight during ovarian stimulation. P values were obtained from linear regression models fitted with generalized estimating equations.

Mean weight gain for the entire cohort was 0.64±1.64 kg, ranging from 2.3 to 6.8 kg. Smaller initial body mass index and higher oocytes retrieved were associated with greater weight gain. Weight gain among patients diagnosed with ovarian hyperstimulation was 47% higher than patients who did not develop ovarian hyperstimulation syndrome (0.94 kg vs 0.64 kg), but this difference was not statistically significant (P=.08). There was no difference in time of return to baseline weight in patients with ovarian hyperstimulation syndrome vs those without ovarian hyperstimulation syndrome after retrieval. There was no difference in return to baseline weight in those with higher number of oocytes retrieved (≥10) vs those with lower number of oocytes retrieved (<10). For patients who underwent multiple cycles, there was no difference in the weight gained in each subsequent cycle compared to the first cycle.

Our study is the first large cohort to report weight changes during antagonist ovarian stimulation cycles, which was on average modest and temporary. Patients of low body mass index, recipients of dual trigger, and ≥10 oocytes retrieved exhibited higher weight gain.