The acute obstetrics (AO) sector in the Netherlands faces two challenges. The increasing difficulty to find personnel and the closing down of several locations have put a major pressure on the existing AO locations. This has led to questions about the quality of the spatial distribution. The measures currently in place are based the travel time to the closest hospital. However, the recent developments have forced AO locations to say ‘no’ when asked to take care of a woman in labour. In other words, the unavailability of beds in the nearest hospital. The current accessibility measures cannot capture this and therefore the concept of substitutability is introduced. The mathematical model for substitutability offers a possibility to assess the effect of elimination of the preferred option. The input parameters for the substitutability calculations have been derived from a stated choice experiment among 151 female residents of the Netherlands. The cost and time parameters were estimated using a multi nominal logit model. A comparison between minimum travel time, LogSum accessibility values and normalised substitutability values guided the assessment of the spatial distribution. This comparison provided insights in new critical areas of the network. The study serves as an exploration of substitutability and it has proved it to be a promising concept for future research.