How does human placental lactogen affect insulin levels during pregnancy?

Human placental lactogen (hPL), also known as human chorionic somatomammotropin, plays a significant role in regulating maternal metabolism during pregnancy. It primarily functions to ensure that the fetus receives a sufficient supply of glucose and nutrients to support its growth and development.

One of the key effects of hPL is that it reduces insulin sensitivity in the mother. As pregnancy progresses, the body needs to accommodate the growing fetus and therefore increases insulin resistance to ensure that adequate glucose remains available in the maternal bloodstream for the fetus. By reducing insulin sensitivity, hPL leads to higher blood glucose levels, which can be utilized by the fetus. This process is also part of the physiological adaptation to ensure that maternal energy stores are maintained.

Insulin production may increase in response to the elevated blood glucose levels, but the primary action of hPL is to alter the insulin sensitivity, allowing more glucose to be available for the fetus rather than for the mother’s needs. Thus, the role of hPL in reducing insulin sensitivity is a critical adaptation in managing maternal-fetal glucose balance during pregnancy.