Maternal Prolactin Secretion Is Phasic During Induced Term and Post-Term Labor

Abstract

Objective: We hypothesized that regimens of labor induction do not alter the biphasic secretion of maternal prolactin (PRL) seen during spontaneous labor.

Methods: Serial blood samples drawn from 12 women before, during, and after induced labor were assayed for PRL and hCG and compared with cervical dilatation and uterine contraction frequency (UCF). Induction methods were cervical ripening with dinoprostone gel (Prepidil) followed by oxytocin infusion (in = 1), anniotomy followed by oxytocin (n = 4), oxytocin followed by anniotomy (n = 3), anniotomy only (n = 2), and oxytocin only (n = 2).

Results: Regardless of the induction method, PRL decreased with advancing cervical dilatation during the first stage of labor and reached a nadir at full dilatation. Prolactin levels then increased rapidly during the second stage, correlating significantly with the increase in UCF, and peaked at 1 hour postpartum before decreasing. Levels of hCG increased during labor and peaked just before or at delivery before rapidly decreasing.

Conclusions: The biphasic secretion of maternal PRL is a fundamental characteristic of active term labor and occurs regardless of the method used to induce labor.

Keywords

Prolactin induced labor cervical dilatation

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References

1. Rigg LA , Yen SSC . Multiphasic prolactin secretion during parturition in human subjects. Am J Obstet Gynecol 1977;128:215-218.

2. Fernandes PA , Szelazek JT , Reid GJ , Wodzicki AM , Allardice JG , McCoshen JA . Phasic maternal prolactin secretion during spontaneous labor is associated with cervical dilatation and second-stage uterine activity. J Soc Gynecol Invest 1995;2:597-601.

3. Bigazzi M , Nardi E. Prolactin and relaxin: Antagonism on the spontaneous motility of the uterus. J Clin Endocrinol Metab 1981;53:665-667.

4. Kornyei JL , Lei ZM , Rao CV . Human myometrial smooth muscle cells are novel targets of direct regulation by human chorionic gonadotropin. Biol Reprod 1995;49:1149-1157.

5. Freeman ME , Smith MS , Nazian SM , Neill JD . Ovarian and hypothalamic control of the daily surges of prolactin secretion during pseudopregnancy in the rat. Endocrinology 1974;94:875-882.

6. Russell KP , Biswas MK . The course and conduct of normal labor and delivery. In: Pernoll ML , ed. Current obstetric and gynecologic diagnosis and treatment. Norwalk, Connecticut: Appleton & Lange, 1991;198-224.

7. Norman GR , Streiner DL PDQ statistics. Hamilton, Ontario: BC Dekker, 1986;47-70.

8. Cunningham FG , MacDonald PC , Gant NF , Leveno KJ , Gilstrap LC . Parturition: Biomolecular and physiological processes. In: Licht J , ed. Williams Obstetrics. 19th ed. Norwalk, Connecticut: Appleton & Lange, 1993:297-361.

9. Cunningham FG , MacDonald PC , Gant NF , Leveno KJ , Gilstrap LC . Dystocia due to abnormalities of the expulsive forces. In: Licht J , ed. Williams obstetrics. 19th ed. Norwalk, Connecticut: Appleton & Lange, 1993:475-491.