Systematic review and meta-analysis of the impact of preconception lifestyle interventions on fertility, obstetric, fetal, anthropometric and metabolic outcomes in men and women

STUDY QUESTION: What is the impact of preconception lifestyle interventions on live birth, birth weight and pregnancy rate? SUMMARY ANSWER: Lifestyle interventions showed benefits for weight loss and increased natural pregnancy rate, but not for live birth or birth weight. WHAT IS KNOWN ALREADY: Evidence on the practice and content of preconception counseling and interventions is variable and limited. STUDY DESIGN, SIZE, DURATION: Systematic review and meta-analysis (MA). Main search terms were those related to preconception lifestyle. Database searched were Ovid MEDLINE(R), EBM Reviews, PsycINFO, EMBASE and CINAHL Plus. No language restriction was placed on the published articles. The final search was performed on 10 January 2017. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants were non-pregnant women of childbearing age intent on conceiving or their male partners. Exclusion criteria include participants with BMI < 18 kg/m(2), animal trials, hereditary disorder in one or both partners and trials focusing solely on alcohol or smoking cessation/reduction, micronutrient supplementation, or diabetes control. Anthropometric, fertility, obstetric and fetal outcomes were assessed. Bias and quality assessments were performed. MAIN RESULTS AND THE ROLE OF CHANCE: The search returned 1802 articles and eight studies were included for analysis. Populations targeted were primarily overweight or obese subfertile women seeking reproductive assistance, with few community-based studies and none including men. MA showed greater reduction in weight (n = 3, P < 0.00001, mean difference: -3.48 kg, 95% CI: -4.29, -2.67, I-2 = 0%) and BMI (n = 2, P < 0.00001, mean difference: -1.40 kg/m(2), 95% CI: -1.95, -0.84, I-2 = 24%) with intervention. The only significant fertility outcome was an increased natural pregnancy rate (n = 2, P = 0.003, odds ratio: 1.87, CI: 1.24, 2.81, I-2 = 0%). No differences were observed for ART adverse events, clinical pregnancy, pregnancy complications, delivery complications, live birth, premature birth, birth weight, neonatal mortality or anxiety. Risk of bias were high for three studies, moderate for three studies and low for two studies, Attrition bias was moderate or high in majority of studies. LIMITATIONS, REASONS FOR CAUTION: Results were limited to subfertile or infertile women who were overweight or obese undergoing ART with no studies in men. The heterogeneous nature of the interventions in terms of duration and regimen means no conclusions could be made regarding the method or components of optimal lifestyle intervention. Attrition bias itself is an important factor that could affect efficacy of interventions. WIDER IMPLICATIONS OF THE FINDINGS: Existing preconception lifestyle interventions primarily targeted overweight and obese subfertile women undergoing ART with a focus on weight loss. It is important to note that natural conception increased with lifestyle intervention. This emphasizes the need for further research exploring optimal components of preconception lifestyle interventions in the broader population and on the optimal nature, intensity and timing of interventions. STUDY FUNDING/COMPETING INTEREST(S): No conflict of interest declared. C.L.H. is a National Heart Foundation Postdoctoral Research Fellow. B.H. is funded by an Alfred Deakin Postdoctoral Research Fellowship. H.J.T. and B.W.M. hold NHMRC Practitioner fellowships. L.J.M. is supported by a SACVRDP Fellowship; a program collaboratively funded by the NHF, the South Australian Department of Health and the South Australian Health and Medical Research Institute. PROSPERO REGISTRATION NUMBER: CRD42015023952.