The effect of one man’s semen on the physiological state of a female and patterns of reproduction related to a consistent partner’s seminal fluid versus a new partner’s.
It has already been established that seminal fluid contains several compounds that may assist in pregnancy maintenance and prevent spontaneous abortion (see Cross-References below). Roberts and Lowe (1975) estimated that about 78% of all human conceptions do not make it full term, so spontaneous abortion is a major factor in human reproduction.
Some researchers have determined that semen familiarity, repeated exposure to the father’s semen, may be a factor in pregnancy maintenance. Live birth rates in couples undergoing in vitro fertilization are significantly improved when women engage in intercourse circa embryo transfer (Tremellen et al. 2000). Treating women who suffer recurrent miscarriages with seminal plasma pessaries improves pregnancy success (Coulam and Stern 1993), and preeclampsia studies show a cumulative benefit of semen exposure over time: limited sex or condom use is linked with increased risk (Klonoff-Cohen et al. 1989). This “cumulative benefit” also implies that this exposure is to seminal fluid of the same male.
Preeclampsia, a cluster of symptoms (including high blood pressure and protein release), is a contributing factor to maternal mortality in the USA and a major cause of perinatal morbidity and mortality (Einarsson et al. 2003; Klonoff- Cohen et al. 1989). One of the major protective factors against preeclampsia appears to be repeated exposure to the father’s semen. Women who have limited exposure to the father’s semen are at increased risk for preeclampsia (Robertson et al. 2003). Preeclampsia also is more likely in pregnancies that occur by artificial insemination, a procedure that sometimes requires the separation of spermatozoa from the seminal fluid (Koelman et al. 2000).
Because the likelihood of preeclampsia is higher for women who are not cohabitating with the child’s father, for women who conceive as a result of artificial insemination, for women who use condoms, and for successive pregnancies that involve a change in paternity, there may be biochemical differences that distinguish one man’s semen from another’s. Dekker et al. (1998) identified changes in “paternity,” the female’s sexual partner, as a predictor in preeclampsia. This implies that it is not only exposure to semen that aids in pregnancy maintenance but the consistent exposure to the father’s semen. Although not all of the factors that distinguish one male’s seminal fluid from another’s have been identified, Doss and Louca (1991) showed that the ratio between testosterone and dihydrotestosterone is different from one man to another due to the heterogenicity of seminal plasma. They hypothesized that this ratio may be useful in identifying a particular man’s semen.
Davis and Gallup (2006) argue that the absence of semen familiarity may be a cue that triggers female mechanisms that evolved to terminate pregnancies that were not in a woman’s reproductive best interests. Making a judicious mate choice and being in a committed relationship with the child’s father are two markers of reproductive success for women. Not only do females have a vested interest in the other 50% of the genes being carried by each of their children in ancestral environments the chances of her children surviving to reproductive age would have depended on the presence of a committed, protective, and provisioning mate.
- Coulam, C. B., & Stern, J. J. (1993). Seminal plasma treatment of recurrent spontaneous abortion. In Serono symposia publications from Raven press (Vol. 97, pp. 205–205). New York: Raven Press.Google Scholar
- Dekker, G. A., Tubbergen, P., Valk, M., Althuisius, S. M., & Lachmeijer, A. M. A. (1998). Change in paternity: A risk factor for preeclampsia in multiparous women. American Journal of Obstetrics and Gynecology, 178(1 Pt 2), S120.Google Scholar