What role does human placental lactogen play during pregnancy?

Human placental lactogen (hPL), produced by the placenta during pregnancy, primarily acts as an insulin antagonist. This means that it helps to promote a state of mild insulin resistance. By doing so, hPL facilitates increased availability of glucose and fatty acids to supply energy to the growing fetus. The mild glucose intolerance it induces is beneficial over the course of pregnancy because it ensures that the fetus has sufficient nutrients for growth and development, while also balancing maternal energy needs.

The other options do not accurately represent the primary functions of hPL. While hPL does have some effects on insulin production, particularly in modulating maternal metabolism, its primary action is not to facilitate insulin production but to create a resistance to its action. Additionally, while hPL can influence body fat metabolism, its role should not be solely categorized as increasing storage; rather, it helps to adjust energy metabolism for both mother and fetus. Moreover, hPL is not directly involved in regulating fetal developmental hormones, but rather, it influences the maternal metabolic environment to support fetal growth.