Three experiments were conducted to determine whether the presence of a male partner during the gestation period facilitates pregnancy maintenance in female prairie voles. In each of the three experiments more females delivered litters when the male was present and separated from them by a wire-mesh barrier than when the male was absent. The effect was present in both nulliparous and parous females. At the ultimate level this suggests a constraint on male mating strategies. At the proximate level these results show that the facilitation of pregnancy maintenance by males (a) occurs in this species and (b) is not dependent on prolonged vaginal stimulation of the female or any other mechanism requiring full contact between partners.