Early and appropriate use of antenatal care services is critical for reducing maternal and neonatal mortality and morbidity. Yet most women in sub-Saharan Africa, including Uganda, do not seek antenatal care until later during pregnancy. This qualitative study explored pregnant women's reliance on social ties for information about initiation of antenatal care. We conducted semi-structured, in-depth interviews with 30 pregnant women seeking their first antenatal care visit at Kawempe Referral Hospital in Kampala, Uganda. Recruitment was done purposively to obtain variation by parity and whether women currently had a male partner. Study recruitment occurred from August 25th 2020 - October 26th, 2020. We used thematic analysis following a two-stage coding process, with both deductive and inductive codes. Deductive codes followed the key domains of social network and social support theory. We found that the most important source of information about antenatal care initiation was these women's mothers. Other sources included their mothers-in-law, female elders including grandmothers, and male partners. Sisters and female friends were less influential information sources about antenatal initiation. One of the primary reasons for relying on their own mothers, mothers-in-law, and elder women was due to these women's lived experience with pregnancy and childbirth. Trust in the relationship was also an important factor. Some pregnant women were less likely to rely on their sisters or female friends, either due to lack of trust or these women's lack of experience with pregnancy and childbirth. The advice that pregnant women received from their mothers and others on the ideal timing for antenatal care initiation varied significantly, including examples of misinformation about when to initiate antenatal care. Pregnant women seemed less likely to delay care when more than one social tie encouraged early antenatal care. Educating women's social networks, especially their mothers, mothers-in-law, and community elders, about the importance of early antenatal care initiation is a promising avenue for encouraging pregnant women to seek care earlier in pregnancy.