Objective To assess by proof of principle whether the individual risk for preterm birth (PTB) should be incorporated into the embryo transfer policy in in vitro fertilisation (IVF). Design and setting A theoretical decision analysis. Methods and main outcome measures A decision tree was built to compare the consequences of different chances of PTB on the outcome of single embryo transfer (SET) or double embryo transfer (DET) in patients with different prognosis of conception. Based on patient characteristics, three scenarios of prognosis of conception were considered and the consequences of SET and DET were calculated for different chances of PTB in these groups. The primary outcome was the health of the children born. Sensitivity analyses were performed for both prognosis for conception and chances of PTB. Results In women with good fertility prospects, one IVF cycle with DET increases the ongoing pregnancy rate (OPR) from 29 to 39% compared with SET, whereas the chances of poor neonatal outcome in these extra pregnancies range from 1.4 to 11% per pregnancy depending on the individual PTB risk. However, for women with poor fertility prospects, DET increases the OPR from 8 to 11% with minimal additional poor neonatal outcome, ranging from 0.3 to 4.0% per pregnancy for women with a low or high PTB risk, respectively. Our findings were robust in multiple sensitivity analyses. Conclusion In an IVF programme, the optimal embryo transfer strategy is dependent on the singleton and multiple pregnancy chances of a woman, but also on her PTB risk. In women with low PTB risk, DET increases the OPR for a small additional risk of neonatal complications. Our analysis pleads for a tailored management strategy, taking into account the personalised prognosis for (multiple) pregnancy and PTB. ; EI Kamphuis, M van Wely, S Repping, F van der Veen, CJM de Groot, P Hompes, BWJ Mol, BM Kazemier