Home uterine activity monitoring was performed by 54 women with singleton, 30 with twin, and 34 with triplet gestations. Data were analyzed to determine the relationship between antepartum uterine activity, preterm labor, and fetal number. Preterm labor in singleton and twin gestations was preceded by significant increases in pre-labor contraction frequency (P less than .01). However, in triplets, preterm labor was not preceded by increased pre-labor contractions. Triplet and twin gestations with term labor were associated with higher baseline contraction frequencies than were high-risk singleton gestations with term labor (P less than .05). Fetal number had no impact on pre-labor contraction intensity, although triplet gestations had a significantly greater proportion of uterine activity occupied by low-amplitude, high-frequency contractility.