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EB Research - Reproductive Epidemiology

Effects of Aspirin in Gestation and Reproduction (EAGeR) Study

Study Objective

The EAGeR Study is a multisite, randomized placebo-controlled clinical trial designed to evaluate the effect of daily low-dose aspirin (LDA) on live-birth rates.


Maximally fertile couples have only an approximately 30-percent chance of conception in a given menstrual cycle, and average monthly fecundity is 20 percent. Estimates of miscarriages and early pregnancy loss vary, ranging from about 15 percent to 30 percent. Available data suggest that LDA has the potential to favorably impact several aspects of reproduction, including conception, implantation, early pregnancy loss, late fetal death, low birth weight, placental insufficiency, and preterm birth. LDA is widely available, inexpensive, and has few maternal side effects. Prior studies focused on narrow aspects of the effects of LDA, such as in vitro fertilization outcome or development of preeclampsia; such studies have also generally begun therapy mid or late gestation. Reproduction is unique in that each stage is inextricably linked. Therefore, better blood flow at the time of conception and implantation may ultimately lead to improved placental function and a reduced risk of preeclampsia, small-for-gestational-age infants, and preterm birth.

Study Design & Progress

The EAGeR trial is a multi-site, prospective, double-blind trial designed to assess the effects of low-dose aspirin on implantation and pregnancy outcome. A total of 1228 regularly menstruating women age 18-40 years with up to two recent miscarriages and who planned to become pregnant again were randomized for this trial. Each woman was randomly assigned to the treatment group with 81 mg aspirin plus 0.4 mg folic acid daily or the placebo group with 0.4 mg folic acid only. Treatment/placebo administration began prior to conception and continued during pregnancy. Fertility monitors were used to assist with timing of intercourse; home digital pregnancy testing kits were used to indicate pregnancy; and, daily urine samples were collected to monitor very early pregnancy and pregnancy loss.

Women were followed by the clinic through regular visits as well as phone interviews. During non-pregnancy follow-up, women were in what was referred to as active follow-up for two menstrual cycles. In this phase, women kept daily diaries and visited the clinic four times, where they filled out questionnaires and provided blood samples, in addition to daily urine samples. After this, they entered passive follow-up for an additional four cycles, visiting the clinic at the end of each cycle. At the end of passive follow-up, if no pregnancy was confirmed, subjects were considered to have completed the study. However, if a woman became pregnant at any time during this stage, she switched to pregnancy follow-up. Women in pregnancy follow-up were followed actively for four weeks post-conception and passively through parturition. Pregnancy loss, pregnancy complications, and perinatal outcomes were monitored throughout pregnancy.

Trial recruitment started in June 15, 2007, and ended in July 2011, with the last screening done on July 14, 2011, and the last randomization on July 15, 2011. Follow-up has been completed as of September 2012 and results of the trial are pending.

Principal Investigator

Enrique F. Schisterman, Ph.D.

DIPHR Collaborators

Last Reviewed: 05/05/2015

Contact Information

Name: Dr Enrique Fabian Schisterman
Chief and Senior Investigator
Epidemiology Branch
Phone: 301-435-6893
Fax: 301-402-2084

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