Suboptimal incubation conditions can negatively affect survival and development of chicken embryos. However, physiological mechanisms that may explain these effects, and the long-lasting consequences are largely unknown. Therefore, the first aim of this thesis was to investigate effects of eggshell temperature (EST) and O2 availability during incubation on survival, development, physiology, and nutrient utilization of chicken embryos. The second aim was to investigate long-lasting effects of suboptimal EST on survival and subsequent performance of broiler chickens. The first study investigated effects of a high (38.9°C) or a normal (37.8°C) EST combined with a low (17%), normal (21%), or high (25%) O2 concentration from day 7 until 19 of incubation on the survival rate, nutrient utilization, and the developmental and physiological status of broiler embryos. The second study investigated effects of high EST on glucose metabolism in broiler embryos using [U-13C]glucose. The third study investigated effects of high EST on growth performance and the incidence of ascites in broiler chickens. Finally, effects of a high EST and a hole in the air cell on the developmental and physiological status of layer hatchlings were investigated. Results showed that a high EST or low O2 availability from the first week of incubation onward negatively affected survival and development of broiler chickens from their perinatal period until slaughter age. Body development of broiler hatchlings was reduced after high EST incubation because of a lower efficiency in protein utilization for growth. This was possibly due to the use of glucogenic amino acids as a glucogenic energy source, because high EST increased the glucose oxidation in broiler embryos during the second half of incubation and resulted in lower hepatic glycogen. Body development was proportional to the O2 availability during incubation. In addition, differences in O2 concentration during incubation seem to affect the development of adaptive mechanisms, and these mechanisms might possible influence nutrient utilization and body development. High EST in the last week of incubation in layer embryos negatively affected hatchling development, but the effect of a hole in the air cell was minimal. Effects of high EST were long-lasting in broiler chickens expressed by a lower body weight and a higher ascites incidence during the growout period. In conclusion, negative effects of suboptimal incubation conditions can be partly explained by changes in nutrient utilization and metabolite levels in the perinatal period and can have long-lasting effects on the survival and performance of broiler chickens.