P-629 Dietary and/or physical activity interventions in women with overweight or obesity prior to fertility treatment – an individual participant data meta-analysis (Venus-IPD)
Authors: Wang Z , Evans-Hoeker E , Cantineau A , Legro R , Thurin-Kjellberg A , Bergh C , Laven J , Sim K , Espinós J , Moholdt T , Rothberg A , Hoek A , Mol B , Groen H , Wang R 
Published: June 2023

Study question

Do dietary and/or physical activity interventions prior to fertility treatment improve live birth rates in women with overweight or obesity?

Summary answer

Dietary and/or physical activity interventions prior to fertility treatment do not significantly increase live birth rates in women with overweight or obesity.

What is known already

Existing guidelines recommend lifestyle interventions based on dietary and/or physical activity targeting at a 5 to 10% reduction in body weight as an initial step prior to fertility treatment for women with infertility and overweight or obesity. However, the evidence underlying this recommendation is limited and findings from recent randomized controlled trials (RCTs) are inconsistent. Individual participant data meta-analysis (IPDMA) has been considered the “gold standard” for evidence synthesis.

Study design, size, duration

We performed an IPDMA of RCTs comparing dietary and/or physical activity interventions as core interventions prior to fertility treatment versus standard advice concerning a healthy diet and physical activity, routine care or no intervention. We searched MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials up to September 2022 to identify potential eligible RCTs.

Participants/materials, setting, methods

After identifying eligible RCTs in women with infertility and overweight or obesity (BMI ≥ 25 kg/m2), we contacted the investigators of eligible RCTs to share the deidentified IPD and established the Venus-IPD Collaboration. The primary outcome was live birth. Secondary outcomes included weight loss and other fertility outcomes. We performed a two-stage random-effects IPDMA as the primary analysis.

Main results and the role of chance

Of 14 eligible RCTs, as of January 2023 we obtained IPD of 9 RCTs with 1715 participants (916 in the intervention group and 799 in the control group). The mean female age was 30.7 years (standard deviation 4.5) and the median baseline BMI was 34.8 kg/m2 (Interquartile range 32.4 to 38.5). The duration of the diet/physical activity interventions ranged from 2.5 to 6 months. Physical activity and/or dietary interventions prior to fertility treatment resulted in more weight reduction compared to those in the control group (9 RCTs, 1715 participants, mean difference –5.71 kg, 95%CI –7.76 to –3.66). The intervention group did not have a significantly higher rate of live birth (8 RCTs, 1697 participants, OR 1.30, 95%CI 0.74 to 2.27, I2=60%) or clinical pregnancy (8 RCTs, 1697 participants, OR 1.22, 95%CI 0.81 to 1.83, I2=28%). The asymmetrical contour-enhanced funnel plot indicates possible small-study effects.

Limitations, reasons for caution

Blinding was not possible due to the nature of the intervention. IPD of three small RCTs are not obtained at this time. The heterogeneity in the type and period for lifestyle interventions and in the follow-up duration was moderate to high.

Wider implications of the findings

Dietary and/or physical activity interventions are effective in reducing body weight in women with overweight or obesity, but such a benefit in weight loss may not translate to improved live birth rates.

Trial registration number

CRD42021266201