Background: Studies showed that pregnant women generally value routine ultrasounds in the first two trimesters because these provide reassurance and a chance to see their unborn baby. This, in turn, might help to decrease maternal anxiety levels and increase the bond with the baby. However, it is unclear whether pregnant women hold the same positive views about a third trimester routine ultrasound, which is increasingly being used in the Netherlands as a screening tool to monitor fetal growth. The aim of this study was to explore pregnant women's experiences with a third trimester routine ultrasound. Methods: We held semi-structured interviews with fifteen low-risk pregnant women who received a third trimester routine ultrasound in the context of the Dutch IUGR RIsk Selection (IRIS) study. The IRIS study is a nationwide cluster randomized controlled trial carried out among more than 13,000 women to examine the effectiveness of a third trimester routine ultrasound to monitor fetal growth. For the interviews, participants were purposively selected based on parity, age, ethnicity, and educational level. We performed thematic content analysis using MAXQDA. Results: Most pregnant women appreciated a third trimester routine ultrasound because it provided them confirmation that their baby was fine and an extra opportunity to see their baby. At the same time they expressed that they already felt confident about the health of their baby, and did not feel that their bond with their baby had increased after the third trimester ultrasound. Women also reported that they were getting used to routine ultrasounds throughout their pregnancy, and that this increased their need for another one. Conclusions: Pregnant women seem to appreciate a third trimester routine ultrasound, but it does not seem to reduce anxiety or to improve bonding with their baby. Women's appreciation of a third trimester routine ultrasound might arise from getting used to routine ultrasounds throughout pregnancy. We recommend to examine the psychological impact of third trimester routine ultrasounds in future studies. Results should be taken into consideration when balancing the gains, which are as yet not clear, of introducing a third trimester routine ultrasound against unwanted side effects and costs.