Human placental lactogen (hPL), also known as human chorionic somatotropin (hCS), is produced by the placenta but exerts its known effect on the mother. Human placental lactogen causes decreased maternal sensitivity to insulin and causes utilization of glucose, thus increasing the glucose available to the fetus. It also promotes release of maternal free fatty acids for utilization by the fetus. It is also thought that hPL stimulates the action of growth hormone in protein deposition, promotes breast growth and preparation for lactation, and maintains the pregnancy by altering the endometrium.

Human placental lactogen rises steadily through pregnancy, maintaining a high plateau during the last trimester. Blood levels of hPL correlate with placental weight and tend to be high in diabetic mothers. Levels also may be elevated in multiple pregnancy and Rh isoimmunization, as well as in nonendocrine tumors that secrete ectopic hPL.

During pregnancy, hPL levels vary greatly with the individual as well as on a day-to-day basis. Thus, serial determinations may be necessary with the client serving as her own control.⁵⁷

[Show Table Outline]

	Conventional Units	SI Units
Men
	<0.5 µg/mL	Not detected
Women Nonpregnant
	<0.5 µg/mL	Not detected
Women Pregnant
5-27 weeks	<4.6 µg/mL	<4.6 mg/L
28-31 weeks	2.4-6.1 µg/mL	2.4-6.1 mg/L
32-35 weeks	3.7-7.7 µg/mL	3.7-7.7 mg/L
36 weeks-term	5.0-8.6 µg/mL	5.0-8.6 mg/L
Diabetic at term	10-12 µg/mL	10.0-12.0 mg/L

[Table Outline]

• Men
• Women Nonpregnant
• Women Pregnant

• During pregnancy, hPL levels vary greatly with the individual as well as on a day-to-day basis.
• Levels tend to be higher in diabetic mothers, multiple gestation, and Rh isoimmunization.

• Detection of placental insufficiency as evidenced by low hPL levels in relation to gestational age
• Support for diagnosing intrauterine growth retardation caused by placental insufficiency, as indicated by hPL levels of less than 4 µg/mL, especially when blood estrogen levels are low
• Prediction of outcome in threatened abortion as indicated by lower than expected levels for the stage of pregnancy
• Support for diagnosing hydatidiform mole and choriocarcinoma as indicated by decreased levels
• Support for diagnosing malignancies associated with elevated levels (e.g., nonendocrine tumors that secrete ectopic hPL)
• Monitoring for the effectiveness of treatment for malignancies associated with ectopic hPL production as indicated by decreasing levels

Nursing Care Before the Procedure

Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I).

• The pregnant client should be informed that several determinations may be necessary throughout the pregnancy.

A venipuncture is performed and the sample is collected in a red-topped tube. The sample should be handled gently to avoid hemolysis and sent promptly to the laboratory.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample.