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Human placental lactogen (hPL) is a hormone produced by the placenta, the organ that develops during pregnancy to help feed the growing baby. This hormone breaks down fats from the mother to provide fuel for the the growing baby. It can lead to insulin resistance and carbohydrate intolerance in the mother.

A test can be done to measure the amount of hPL in the blood. The test is only done on pregnant women.

Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

No special preparation is needed.

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

The test is done to see how well the placenta is functioning.

A rising HPL value during pregnancy is normal.

Abnormal results may be a sign of abnormal (usually insufficient) placenta function.

HPL values are decreased with:

• Toxemia
• Aborting hydatidiform mole
• Choriocarcinoma
• Placental insufficiency

• Multiple pregnancies (twins or more)
• Placental site trophoblastic tumor
• Intact molar pregnancy
• Diabetes
• Rh incompatibility

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others. Other risks are rare, but may include:

• Excessive bleeding
• Fainting or feeling lightheaded
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

The uses of this test are limited to certain rare conditions and medical research.

HPL; Human chorionic somatomammotropin; HCS

Reiter EO, Rosenfeld RG. Normal and aberrant growth. In: Kronenberg HM, Shlomo M, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 23.

Baschat AA, Galan HL, Ross MG, Gabbe SG. Intrauterine growth restriction. In: Gabbe SG, Niebyl JR, Simpson JL, eds. Obstetrics: Normal and Problem Pregnancies. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2007:chap 29.

Updated by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Redmond, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.