Association of number of retrieved oocytes with live birth rate and birth weight: an analysis of 231,815 cycles of in vitro fertilization

Abstract

Objective To determine if number of oocytes correlates with live birth rate and incidence of low birthweight (LBW). Design Retrospective cohort. Setting N/A. Patients Women undergoing fresh embryo transfer utilizing either autologous (n=194,627) or donor (n=37,188) oocytes whose cycles were reported to the Society for Assisted Reproductive Technology 2004–2010. Main outcome measures Live birth rate, birthweight, birth weight z-score, LBW. Interventions None. Results For both autologous and donor oocyte cycles, increasing number of oocytes retrieved paralleled live birth rate and embryos available for cryopreservation in most analyses performed with all models adjusted for age and prior births. For cycles achieving singleton pregnancy using autologous oocytes via transfer of 2 embryos, a higher number of oocytes retrieved was associated with lower mean birth weight, lower birthweight z-score, and greater incidence of LBW. In contrast, for cycles using donor oocytes, there was no association of oocyte number retrieved with measures of birthweight. Conclusions A higher number of oocytes retrieved was associated with an increased incidence of LBW in autologous singleton pregnancies resulting from transfer of 2 embryos but not in donor oocyte cycles. Although the effect of high oocyte number on the incidence of LBW in autologous cycles was of modest magnitude, further study is warranted to determine if a subgroup of women may be particularly vulnerable.

Endometrial injury, the quality of embryos, and blastocyst transfer are the most important prognostic factors for in vitro fertilization success after previous repeated unsuccessful attempts

“…In conception cycles compared to non-conception cycles, higher number of oocytes retrieved, all available embryos, good-quality embryos, blastocysts, freezing surplus blastocysts, proportion of cycles with embryo transfer of at least one good-quality embryo, and lower dose of gonadotrophins were all related to a higher clinical pregnancy rate which is in consistence with findings of other authors [3, 15–18]. Women who did not get pregnant were older that those who did, but this difference did not reach statistical significance.…”

Pregnancy, birth, and infant outcomes by maternal fertility status: the Massachusetts Outcomes Study of Assisted Reproductive Technology

“…Other factors affecting the endometrium and uterine environment may also be associated with adverse outcomes. Both gonadotropin dose and number of oocytes retrieved are associated with reduced live birth rates and decrements in birthweight (62, 63). …”

Total number of oocytes and zygotes are predictive of live birth pregnancy in fresh donor oocyte in vitro fertilization cycles

“…Prior studies have evaluated an association between the number of mature oocytes retrieved and pregnancy outcomes in both autologous and donor IVF cycles respectively (12,16–19). Consistent with our findings, Baker et al found that an increasing number of total number of oocytes retrieved was associated with greatest probability of live birth rate in both autologous and donor cycles.…”

“…Mirkin et al suggested that a baseline follicle stimulating hormone (FSH) between 4 and 8 IU/L was predictive of IVF outcomes (8). In contrast, Barton et al did not observe an association between FSH levels and LB outcomes (11), and observed that the total number of oocytes retrieved was associated with greatest probability of live birth (12). Following adjustment for oocyte donor age, Cohen et al found that the number of oocytes was not associated with pregnancy outcome (7,12).…”

“…In contrast, Barton et al did not observe an association between FSH levels and LB outcomes (11), and observed that the total number of oocytes retrieved was associated with greatest probability of live birth (12). Following adjustment for oocyte donor age, Cohen et al found that the number of oocytes was not associated with pregnancy outcome (7,12). Additionally, Letterie et al found that there were no differences in fertilization rates or clinical pregnancy rates regardless of the number of oocytes retrieved, ranging from 3 to >25 (13).…”