Peptide directoryReproductive

Human placental lactogen

The placenta’s most abundant protein, a gram a day at term, retuning the mother.

Where it comes from

Made in
Syncytiotrophoblast of the placenta
Sent out by
Rises through pregnancy in step with placental mass
Acts on
  • Maternal fat (lipolysis)
  • Maternal pancreas (beta cell growth)
  • Breast
  • Fetal tissues, through IGF

What it does

  • Frees fatty acids for the mother so glucose is spared for the fetus 1
  • Makes the mother’s islets expand to meet pregnancy’s insulin demand 1
  • Prepares the breast for milk alongside prolactin

In medicine

  • Once measured as a test of placental function; superseded by ultrasound and no longer offered
  • Pregnancies have been reported in which both lactogen genes, and the placental growth hormone gene between them, are deleted: one such baby was severely growth-restricted but otherwise normal, and earlier cases were unremarkable, so how far it is needed is unsettled 2

Beyond the body’s own use

  • Not a treatment and not a target: no medicine copies it and none blocks it
  • The live question is why a protein made by the gram can be missing without an obvious syndrome, which is the argument that it overlaps with placental growth hormone and prolactin 1

Sources

  1. Handwerger and Freemark, The roles of placental growth hormone and placental lactogen in fetal growth, Journal of Pediatric Endocrinology and Metabolism 2000
  2. Rygaard et al., Absence of human placental lactogen and placental growth hormone during pregnancy, Human Genetics 1998

This card describes what a medicine is for and what the evidence says; it recommends nothing. Talk to your clinician about anything you read here.