Antibiotics prior to embryo transfer in ART

In vitro fertilisation (IVF) describes an assisted reproductive technology (ART) during which a woman undergoes ovarian stimulation, surgical retrieval of eggs, fertilisation of eggs outside of the body, and finally the transfer of resulting embryo(s) into the uterus by an embryo transfer (ET) procedure. During an ET, the embryo(s) is passed through the cervix by means of a catheter. Many variables affect the chance of pregnancy after ET, including embryo quality, uterine factors and the embryo transfer technique. High levels of bacteria and other organisms in the upper genital tract have a detrimental effect on pregnancy rate after ET. Administration of antibiotics prior to ET may reduce the growth of these organisms and improve the outcomes of IVF. This review considered the question of whether antibiotics given at any time prior to ET affect pregnancy rates and other important outcomes of IVF.

In the only study which addressed this question, the use of an amoxycillin and clavulanic acid antibiotic regimen had no effect on clinical pregnancy rate despite demonstrating a reduction in upper genital tract colonisation. The effect on live birth rate is unknown.

The findings of this review do not support the use of an amoxycillin and clavulanic acid antibiotic regimen prior to ET for the purposes of improving IVF success. The effect of alternative antibiotic regimens on IVF outcomes is unknown and needs further research.

Authors' conclusions: 

This review suggests that the administration of amoxycillin and clavulanic acid prior to embryo transfer reduced upper genital tract microbial contamination but did not alter clinical pregnancy rates. The effect of this intervention on live birth is unknown. There are no data from randomised controlled trials to support or refute other antibiotic regimens in this setting.

Future research is warranted to assess the efficacy of alternative antibiotic regimens. Researchers should assess live birth as the primary outcome and address quantitative microbial colonization as a secondary outcome.

Read the full abstract...

Embryo transfer (ET) involves the placement of one or more embryos into the uterine cavity, usually by passing a catheter through the cervical os. ET is the final step in an assisted reproductive technology (ART) cycle, where a woman has undergone controlled ovarian stimulation, egg retrieval and in vitro fertilisation of her eggs. Despite the transfer of high quality embryos, many ETs do not result in a pregnancy. There are many factors which may affect the success of ET, including the presence of upper genital tract microbial colonisation. The administration of antibiotics prior to ET has been suggested as an intervention to reduce levels of microbial colonisation and hence improve pregnancy rates.


To evaluate the effectiveness and safety of antibiotic administration prior to ET during ART cycles.

Search strategy: 

We searched the Menstrual Disorders and Subfertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library, MEDLINE, Ovid MEDLINE® In-Process & Other Non-Indexed Citations, Ovid MEDLINE® Daily and Ovid MEDLINE® (from inception to February 2011), Ovid EMBASE (January 2010 to February 2011), Ovid PsycINFO, CINAHL, LILACS, trial registers for ongoing and registered trials, citation indexes, ClinicalStudyResults, PubMed, OpenSIGLE database and for for herbal and complimentary therapy protocols and reviews.

Selection criteria: 

Only randomised controlled trials were included.

Data collection and analysis: 

The titles and abstracts of articles identified by the search were screened by one review author for eligibility. Two review authors then independently examined the full text articles for suitability for inclusion in the review. Data were extracted independently by two review authors.

Main results: 

We identified four potential studies, of which three were excluded.

The included trial reported clinical pregnancy rates but not live births. There was no evidence of a difference in clinical pregnancy rate between those receiving an amoxycillin and clavulanic acid antibiotic combination (64/178: 36%) and those not (61/172: 35.5%) (OR1.02, 95% CI 0.66 to 1.58). Genital tract colonisation was significantly reduced in women receiving this antibiotic regimen (OR 0.59, 95% CI 0.37 to 0.95).