Prolactin Relationship with Fertility and In Vitro Fertilization Outcomes-A Review of the Literature

Abstract

Hyperprolactinemia is a known cause of amenorrhea and infertility. However, there is an increasing body of evidence suggesting that prolactin is involved in multiple physiological aspects of normal reproduction. Thus, the present paper aims to review the current literature regarding the relationship between serum prolactin level and in vitro fertilization (IVF)/intracytoplasmic sperm injection outcome and the role of dopamine agonists treatment in IVF success. Moreover, the mechanisms by which prolactin may exert its role in fertility and infertility were summarized. Although not all studies agree, the available evidence suggests that higher prolactin levels in follicular fluid are associated with increased oocytes competence, but also with positive effects on corpus luteum formation and survival, endometrial receptivity, blastocyst implantation potential and survival of low-motile sperm. Transient hyperprolactinemia found in IVF cycles was reported in most of the studies not to be related to IVF outcome, although a few reports suggested that it may be associated with higher implantation and pregnancy rates, and better-cumulated pregnancy outcomes. Administration of dopamine agonists for hyperprolactinemia preceding IVF treatment does not seem to negatively impact the IVF results, while treatment of transient hyperprolactinemia during IVF might be beneficial in terms of fertilization rates and conception rates. Due to limited available evidence, future studies are necessary to clarify the optimal level of circulating prolactin in patients performing IVF and the role of dopamine agonist treatment.

Keywords: hyperprolactinemia; in vitro fertilization; pregnancy rate; prolactin; transient hyperprolactinemia.

Figure 1

The mechanism of induction of hypogonadotropic hypogonadism by hyperprolactinemia. Prolactin acts through prolactin receptors on metastasis-suppressor kisspeptin-1 neurons, with downstream disruption of GnRH secretion, followed by decreased production of gonadotropins, hypogonadotropic hypogonadism and anovulation.

Figure 2

The mechanisms of reduced female fertility in hyperprolactinemia. Hyperprolactinemia may contribute to infertility by inducing decreased GnRH production, granulosa cell dysfunction, inhibition of corpus luteum function, endometrial dysfunction and decreased implantation.

Figure 3

Prolactin roles in female fertility. Prolactin has several roles in female fertility by influencing oocytes maturation and fertilizability, early corpus luteum formation and survival, improvement of blastocyst implantation potential, decidualization, embryo-endometrial synchrony and acting as a pro-survival factor for low-motile sperm.