Table 1 Characteristics of included studies
First author, publication year | Methodology | Single center or multi center | Location | Study period | Definition of standard trigger timing | Intervention and Comparison | Sample Size | Trigger drug and dose | Fertilization method | Embryo transfer strategy | Primary outcome | Findings |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Kolibianakis, 2004 [15] | RCT | single center | Belgium | 2002.5-2003.4 | at least three follicles were 17 mm | standard trigger VS 48 h-delay trigger | 194/196 | hCG,10000 IU | IVF/ICSI | fresh embryo | ongoing pregnancy rate | Prolongation of the follicular phase in patients stimulated with rec-FSH and GnRH antagonists for IVF does not affect oocyte or embryo quality but is associated with a significantly lower ongoing pregnancy rate. |
Tremellen1, 2010 [13] | Cohort | single center | Australia (Adelaide) | 2008 | two or more follicles ≥ 17 mm in diameter, with the majority of follicles being ≥ 14 mm | standard trigger VS 24 h-delay trigger | 221/251 | hCG,5000 IU | IVF/ICSI | fresh embryo | live birth rate | It is possible to safely avoid weekend oocyte retrievals (ORs) during GnRH antagonist cycles by simply advancing an ideal Saturday OR to Friday, and delaying an ideal Sunday OR to Monday, without adversely impacting on IVF live birth outcomes. |
Kyrou, 2011 [16] | RCT | single center | Belgium | 2010.1-2011.4 | three or more follicles of size ≥ 16 mm | standard trigger VS 24 h-delay trigger | 52/54 | hCG,10000 IU | IVF/ICSI | fresh embryo | ongoing pregnancy rate. | Earlier administration of hCG is not associated with the probability of pregnancy in cycles stimulated with recombinant FSH and GnRH antagonists. |
Morley, 2012 [17] | RCT | single center | United Kingdom | 2002–2007 | ≥ 3 follicles ≥ 17 mm in diameter | standard trigger VS 24 h-delay trigger VS 48 h-delay trigger | 39/37/31 | hCG,10000 IU | IVF/ICSI | fresh embryo | the number of oocytes retrieved | Delaying hCG administration had no significant negative impact upon morphological quality of embryos, availability of surplus embryos for freezing or pregnancy outcomes. Postponing hCG may enable increased flexibility of cycle scheduling to avoid weekend procedures. |
Davar, 2017 [6] | RCT | single center | Iran | 2016.8-2016.10 | at least 3 follicles with ≥ 18 mm diameters | standard trigger VS 24 h-delay trigger | 43/42 | —— | IVF/ICSI | fresh embryo | Number of metaphase II oocytes, number of fertilized oocytes, number of embryo formation. | Delaying of triggering oocyte maturation by 24 h in antagonist protocol with not-elevated progesterone (progesterone ≤ 1 ng/ml) have not beneficial nor harmful effect on the number of mature oocytes (MII) and other in vitro fertilization cycle characteristics. |
Awonuga, 2018 [7] | Cohort | single center | USA | 2003.1-2009.12 | two mature follicles, defined as ≥ 18 mm | standard trigger VS delay trigger | 121/79 | —— | IVF/ICSI | fresh embryo | - | delaying hCG administration to allow further growth of the medium-sized follicles added further days of superovulation and cost without improvement in CPR and LBR. |