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/m2, 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, I2 = 0%) and BMI (n = 2, P < 0.00001, mean difference: -1.40 kg/m2, 95% CI: -1.95, -0.84, I2 = 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, I2 = 0%). No differences were observed for ART adverse events, clinical pregnancy, pregnancy complications, delivery