Assessment of multiple intrauterine gestations from ovarian stimulation (AMIGOS) trial: baseline characteristics

Fertil Steril. 2015 Apr;103(4):962-973.e4. doi: 10.1016/j.fertnstert.2014.12.130. Epub 2015 Feb 20.


Objective: To identify baseline characteristics of women with unexplained infertility to determine whether treatment with an aromatase inhibitor will result in a lower rate of multiple gestations than current standard ovulation induction medications.

Design: Randomized, prospective clinical trial.

Setting: Multicenter university-based clinical practices.

Patient(s): A total of 900 couples with unexplained infertility.

Intervention(s): Collection of baseline demographics, blood samples, and ultrasonographic assessments.

Main outcome measure(s): Demographic, laboratory, imaging, and survey characteristics.

Result(s): Demographic characteristics of women receiving clomiphene citrate (CC), letrozole, or gonadotropins for ovarian stimulation were very consistent. Their mean age was 32.2 ± 4.4 years and infertility duration was 34.7 ± 25.7 months, with 59% primary infertility. More than one-third of the women were current or past smokers. The mean body mass index (BMI) was 27 and mean antimüllerian hormone level was 2.6; only 11 women (1.3%) had antral follicle counts of <5. Similar observations were identified for hormonal profiles, ultrasound characterization of the ovaries, semen parameters, and quality of life assessments in both male and female partners.

Conclusion(s): The cause of infertility in the couples recruited to this treatment trial is elusive, as the women were regularly ovulating and had evidence of good ovarian reserve both by basal FSH, antimüllerian hormone levels, and antral follicle counts; the male partners had normal semen parameters. The three treatment groups have common baseline characteristics, thereby providing comparable patient populations for testing the hypothesis that use of letrozole for ovarian stimulation can reduce the rates of multiples from that observed with gonadotropin and CC treatment.

Clinical trial registration number: NCT 01044862.

Trial registration: NCT01044862.

Keywords: Unexplained infertility; aromatase inhibitors; clomiphene citrate; gonadotropins; letrozole; multiple gestations.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Clomiphene / therapeutic use*
  • Female
  • Fertility Agents, Female / classification
  • Fertility Agents, Female / therapeutic use*
  • Gonadotropins / therapeutic use*
  • Humans
  • Infertility, Female / epidemiology*
  • Infertility, Female / therapy*
  • Letrozole
  • Male
  • Nitriles / therapeutic use*
  • Ovulation Induction / adverse effects
  • Ovulation Induction / methods
  • Ovulation Induction / statistics & numerical data*
  • Pregnancy
  • Pregnancy Outcome / epidemiology
  • Pregnancy, Multiple / statistics & numerical data*
  • Quality of Life
  • Triazoles / therapeutic use*


  • Fertility Agents, Female
  • Gonadotropins
  • Nitriles
  • Triazoles
  • Clomiphene
  • Letrozole

Associated data