<p>　　Previous studies have revealed that interpersonal relations influence the psychological wellbeing of pregnant women and mothers of 1-year olds. Routine interaction affects the provision and receipt of assistance and it also serves to alleviate routine stress. This assumption presumably applies to pregnant women and mothers with an infant as well. However, the ways in which these women routinely communicate with others and the role that communication plays have not been sufficiently examined.</p><p>　　The purpose of this study was to investigate routine communication and its role for pregnant women and mothers with an infant. Semi-structured interviews were conducted with 21 pregnant women and 10 mothers with a 1-year-old. Interview transcripts were analyzed using the modified grounded theory approach (M-GTA).</p><p>　　Results revealed that both pregnant women and mothers of a 1-year-old were trying to adapt to changes in their environment by communicating with their husbands, their own mothers, old friends, friends who were mothers themselves, and work colleagues. During pregnancy, pregnant women developed a multi-tiered relationship with their husbands while relying on their own mothers and old friends. During child rearing after the child was born, the marital relationship appeared to strengthen and mothers' attitudes began to center on the family. In addition, mothers continued to actively form relationships with friends who were mothers themselves, but mothers grew apart from their own mothers and old friends. However, mothers valued their relationships with old friends, so they sought to maintain those relationships by selecting applicable conversation topics and means of communication.</p>