Table 1.

Characteristics of the studies included in the meta-analysis.

Investigator (year), country	Study design	Inclusion criteria	Sample size	Main outcomes eligible for meta-analysis	Adjusted for the following confounding factors
Moran (2011), Australia22	RCT	18–40 years, 28 ≤ BMI < 45 kg/m2, GnRH agonist protocol	Lifestyle treatment (diet & exercise) (n = 18), control (n = 20)	Live birth rates Weight change Clinical pregnancy rate	Unadjusted
Sim (2014), Australia23	RCT	18–37 years, BMI ≥ 30 kg/m2, intending to commence IVF, ICSI, or cryostored embryo transfer treatment at RPAH Fertility Unit	Intensive dietary support & activity intervention (n = 27), Allocated to standard care (n = 17)	Live birth rates Weight change Clinical pregnancy rate Miscarriage rate (< 6 weeks, 6–12 weeks)	Number of fertility treatment cycles
Mutsaerts (2016), Netherlands24	RCT	Subfertile women, 18–39 years, 29 ≤ BMI < 40 kg/m2	6 months’ lifestyle-intervention program (n = 280), control (n = 284)	Live birth rates Weight change Clinical pregnancy rate Ongoing pregnancy rate Multiple pregnancy rate Ectopic pregnancy rate	Unadjusted
Einarsson (2017), Sweden25	RCT	< 38 years, planning IVF, 30 ≤ BMI < 35 kg/m2	Weight reduction group (n = 152), control (n = 153)	Live birth rates Weight change Clinical pregnancy rate Ectopic pregnancy rate	Unadjusted
Espinós (2017), Spain26	RCT	18–37 years, 30 < BMI < 40 kg/m2, presenting for their first IVF cycle	12-week diet and exercise intervention (n = 21), control (n = 20)	Live birth rates Weight change Multiple pregnancy rate Miscarriage rate	Unadjusted
Wang (2021), China27	RCT	20–40 years, 25 kg/m2 ≤ BMI, scheduled for IVF or ICSI	Orlistat (n = 439), placebo (n = 438)	Live birth rate Weight change Clinical pregnancy rate Ongoing pregnancy rate Miscarriage rate Ectopic pregnancy rate	Unadjusted

RCT, randomized controlled trial; BMI, body mass index; GnRH, gonadotropin-releasing hormone; IVF, in vitro fertilization; ICSI, intracytoplasmic sperm injection.