This meta-analysis of 39 studies containing 118 individual diets explored the effects of early lactation diets on the proportion of cows pregnant (PP) to service and calving to pregnancy interval. It was hypothesized that diet, intake of nutrients, and production after calving would affect these reproductive measures. Four negative binomial multivariable models, that included a random effect of study, were used to examine the effects of diet and production on proportion pregnant. They examined; i) output of products, ii) balance or duodenal intakes of nutrients, iii) oral intake of nutrients, or iv) dietary percentage of nutrients. The multivariable models identified that increased milk protein yield (kg/d; Relative Risk (RR) 0.445, 95% CI 0.281 to 0.703), sugar intake (kg/d; RR 0.813, 95% CI 0.713 to 0.927), and sugar % (% DM; RR 0.96, 95% CI 0.930 to 0.990) were associated with a decrease in RR for PP. Metabolizable energy balance (MJ/d; RR 1.004, 95% CI 1.001 to 1.008), duodenal c14:0 intake (g/d; RR 1.008, 95% CI 1.0005 to 1.015), increased fatty acid intake (kg/d; RR 1.0003, 95% CI 1.000 to 1.001), and starch intake (kg/d; RR 1.061, 95% CI 1.006 to 1.118) were associated with improved RR for PP. Univariably, increased metabolizable energy balance (MJ/d) was associated with a shorter calving to pregnancy interval, while increased milk production (kg/d) was, and increased intake of lysine and threonine (g/d) tended to be, associated with longer time to pregnancy. Nutritional management was associated with reproductive success. The study identified associations of specific carbohydrate fractions to proportion pregnant. The importance of dietary fats and positive energy and protein balances in early lactation for improved fertility outcomes was also supported.