Women, weight, and fertility: the effect of body mass index on the outcome of superovulation/intrauterine insemination cycles.

OBJECTIVE: To determine the fecundity of overweight and obese infertile women treated with gonadotropins and undergoing intrauterine insemination (IUI).
DESIGN: Retrospective study.
SETTING: Academic infertility clinic. PATIENT(S): Four hundred seventy-seven women undergoing 1,189 ovulation induction (OI)/IUI cycles stratified by body mass index (BMI). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): BMI groups were compared regarding the following: gonadotropin dose, duration of treatment, peak E(2), number of follicles (total, large, and medium size), E(2)/follicle, endometrial thickness, spontaneous abortion, and clinical and multiple pregnancy rates. RESULT(S): There was a significant trend toward higher medication requirements and lower E(2) levels with increasing BMI. BMI was inversely associated with [1] the E(2) level per produced preovulatory follicle and [2] the number of medium-size follicles. Furthermore, BMI was inversely associated with the number of medium, large, and total follicles divided by total FSH dose, suggesting that women with a higher BMI develop a lower number of medium and/or large follicles at a given total FSH dose. BMI was positively associated with endometrial thickness, and endometrial thickness was positively associated with pregnancy. Mean number of cycles required to conceive, clinical pregnancy, and spontaneous abortion rates did not differ significantly among the different BMI categories. CONCLUSION(S): Obese women require higher doses of medication and produce fewer follicles for a given dose, but once medication and response are adjusted to overcome the weight effect, the success of the treatment cycle is comparable to that of normal weight women.