Common techniques used to synchronize eukaryotic cells in the cell cycle often impose metabolic stress on the cells or physically select for size rather than age. To address these deficiencies, a minimally perturbing method known as the “baby machine” was developed previously. In the technique, suspension cells are attached to a membrane, and as the cells divide, the newborn cells are eluted to produce a synchronous population of cells in the G1 phase of the cell cycle. However, the existing “baby machine” is only suitable for cells which can be chemically attached to a surface. Here, we present a microfluidic “baby machine” in which cells are held onto a surface by pressure differences rather than chemical attachment. As a result, our method can in principle be used to synchronize a variety of cell types, including cells which may have weak or unknown surface attachment chemistries. We validate our microfluidic “baby machine” by using it to produce a synchronous population of newborn L1210 mouse lymphocytic leukemia cells in G1 phase.