Abstract Study question How do women’s modes of conception, self-mastery, perceived stress, and cognitive appraisal contribute to personal growth during two phases of pregnancy? Summary answer Women who conceive through IVF experience the highest level of personal growth; Higher challenge appraisal is associated with higher personal growth in both study phases. What is known already Pregnancy can be experienced as a complex and stressful period, especially for women who conceive through fertility treatments. However, stress also constitutes an opportunity to experience personal growth, as shown by a few studies that examined women once during pregnancy. One study focused on cognitive appraisal and found that as women appraise their pregnancy as more challenging, they experience a higher level of growth during the third trimester of pregnancy. Additionally, scarce evidence indicates that personal growth increases from the third trimester to the postpartum period. Study design, size, duration The current study consists of three groups that differ in their modes of conception: spontaneous; first-line fertility treatments, such as intrauterine insemination (IUI); and in-vitro fertilization (IVF). A prospective design was employed in two phases during pregnancy: the first or second trimester (Phase 1; n = 400) and the third trimester (Phase 2; n = 268). Participants/materials, setting, methods Israeli pregnant women (age M = 32, SD = 4.5) were recruited by gynecologists and fertility specialists via several large women's health centers in Israel. Women completed five self-report questionnaires: Posttraumatic growth, self-mastery, perceived stress, cognitive appraisal, and questions relating to background and pregnancy-related details. Main results and the role of chance The findings indicate that women who conceived spontaneously have a higher sense of self-mastery than women who conceived through IVF. Whereas no differences were found between the study groups in perceived stress, the IVF group experienced higher personal growth than the spontaneous group during early pregnancy, but not during advanced pregnancy. The hierarchical regressions conducted to examine the contribution of the study variables to personal growth revealed that they accounted for 30.6% of its variance in the early phase of pregnancy and 23.6% in the advanced phase. In the early phase, lower self-mastery, a lower appraisal of the pregnancy as a threat, and a higher appraisal of the pregnancy as a challenge were associated with higher personal growth. In the advanced phase of pregnancy, only being first-time expecting mothers and higher challenge appraisal predicted personal growth. Finally, personal growth was greater in advanced pregnancy than in the earlier stage. Limitations, reasons for caution The findings rely on self-report measures, which may be biased. Also, the study was conducted in Israel, in which women who want to have children are eligible to receive fertility treatments sponsored by the health insurance fund up to the age of 44, thus should be considered in this context. Wider implications of the findings Women may experience positive implications following challenging conceiving circumstances. This can be translated to interventions aimed at strengthening women's internal resources and positive perceptions, as well as to raising awareness among professionals in fertility units that, alongside difficulties entailed in the process, it can also constitute an opportunity for growth. Trial registration number not applicable