Hyperemesis gravidarum is a severe form of nausea and vomiting during pregnancy, primarily attributed to hormonal changes. Understanding the hormonal factors that contribute to this condition is crucial in identifying its causes. Let's analyze the options to determine which is NOT a cause of hyperemesis gravidarum:

1. Excess of Chorionic Gonadotropin: Human Chorionic Gonadotropin (hCG) is a hormone produced by the placenta shortly after conception. High levels of hCG are closely associated with nausea and vomiting during pregnancy, particularly in the first trimester. Therefore, excess hCG is indeed a basis for hyperemesis gravidarum.
2. Excess of Human Placental Lactogen: Human Placental Lactogen (hPL), also known as human chorionic somatomammotropin, is primarily involved in the metabolic changes during pregnancy, aiding in fetal growth by modifying the metabolic state of the mother. This hormone is not directly linked to causing nausea or vomiting and hence is NOT considered a hormonal basis for hyperemesis gravidarum.
3. Excess of Progesterone: Progesterone levels increase during pregnancy and can cause relaxation of the smooth muscles, including those of the gastrointestinal tract, potentially contributing to nausea. Therefore, an excess of progesterone is considered a factor in hyperemesis gravidarum.
4. High serum levels of Estrogen: Estrogen levels also rise during pregnancy and are believed to play a role in nausea and vomiting. The increase in estrogen contributes to the complex hormonal changes affecting the digestive system, making it a relevant factor in hyperemesis gravidarum.

Conclusion: Among the options given, "Excess of Human Placental Lactogen" is NOT a hormonal basis for hyperemesis gravidarum, as its primary role does not align with the causative factors of nausea and vomiting during pregnancy. Therefore, the correct answer is:

Excess of Human Placental Lactogen