In Support of the Theory
Given the interworking of so many different hormones in the human body, it's feasible that an imbalance could cause numerous problems. It's clear that hyperprolactinemia can cause infertility, and doctors often treat high prolactin levels in women having trouble conceiving.
In the case of recurrent miscarriages and prolactin, one 1998 study found elevated prolactin levels in women who had multiple pregnancy losses and improvements in pregnancy outcome after treating the elevated prolactin. The findings have not been verified in a large scale study, but because the treatment is thought to be safe, some doctors test for and treat elevated prolactin when testing women for causes of recurrent miscarriages -- similar to in women suffering infertility.
In Opposition of the Theory
The studies that have found a link between high prolactin levels and miscarriage were not large enough to be conclusive.
In addition, researchers still do not fully understand the functioning of prolactin in the body, and many feel that it is too early to say whether or not the elevated prolactin levels in women with miscarriages have any clinical relevance. Other factors could theoretically account for higher prolactin levels in women with miscarriages, so many doctors prefer to wait for more evidence before considering prolactin as a cause of recurrent miscarriages.
Where It Stands
Some doctors regularly test prolactin in couples with recurrent miscarriages and prescribe medications, such as bromocriptine or cabergoline, to reduce the prolactin levels. These medications appear to be safe to use during pregnancy and are commonly used for women with infertility from hyperprolactinemia. But right now, there are no formal recommendations to test for and treat prolactin in women with recurrent miscarriages.
Colao, Annamaria, Roger Abs, David Gonzalez Barcena, Phillipe Chanson, Wolfgang Paulus, and David Kleinberg, "Pregnancy outcomes following cabergoline treatment: extended results from a 12-year observational study." Clinical Endocrinology Jan 2008. Accessed 20 Apr 2008.
Freeman, Marc E., Bela Kanyiecska, Anna Lerant, and Gyorgy Nagy, "Prolactin: Structure, Function, and Regulation of Secretion." Physiological Reviews Oct 2000. Accessed 20 Apr 2008.
Gurbuz, B., S. Yalti, C. Ficicioglu, S. Ozden, G. Yildirim, and C. Sayar, "Basal hormone levels in women with recurrent pregnancy loss." Gynecological Endocrinology Aug 2003. Accessed 20 Apr 2008.
Hirahara, F., N. Andoh, K. Sawai, T. Hirabuki, T.Uemura, and H. Minaguchi, "Hyperprolactinemic recurrent miscarriage and results of randomized bromocriptine treatment trials." Fertility and Sterility Aug 1998. Accessed 20 Apr 2008.
Rossi, A.M., S. Vilska, P.K. Heinonen, "Outcome of pregnancies in women with treated or untreated hyperprolactinemia. European Journal of Obstetrics and Gynecology and Reproductive Biology Dec 1995. Accessed 20 Apr 2008.
Serri, Omar, Constance L. Chik, Ehud Ur, and Shereen Ezzat, "Diagnosis and management of hyperprolactinemia." Canadian Medical Association Journal 16 Sept 2003. Accessed 20 Apr 2008.
Sonino, N. C. Navarrini, C. Ruini, F. Fallo, M. Boscaro, and G.A. Fava, "Life events in the pathogenesis of hyperprolactinemia." European Journal of Endocrinology Jul 2004. Accessed 20 Apr 2008.
Wand, Gary S. "Diagnosis and Management of Hyperprolactinemia." Jan 2003. Accessed 20 Apr 2008.