Abstract: One of the central questions in the metaphysics of pregnancy is this: Is the fetus a part of, or contained by, the gestator? In this paper I seek not to answer this question, but rather to highlight various alternative mereotopological options for the fetus-gestator relationship and to raise methodological concerns regarding how to adjudicate between these options. Should we be looking for evidence and data within the realm of metaphysics or the philosophy of biology? Should we be learning about pregnancy from our philosophical and scientific theories or should we update our theories based upon what we otherwise know about pregnancy? My positive suggestion will be to adopt a method of reflective equilibrium. The aim of this is to ensure that pregnancy be included in the tribunal of experience to which our theories are held up against such that our theories can accommodate what we say about pregnancy, whilst also ensuring that what we say about pregnancy be theoretically informed.