This study examined the contribution of birth circumstances (premature and full-term birth) and individual and spousal factors (attachment orientations, parental self-efficacy and perceived infant temperament), measured 1 month post-partum, to the personal growth of first-time parents (n = 121) 1 and 5 months post-partum. The study overcame the limitations of prior research by accurately measuring actor effects while controlling for and assessing partner effects, by applying the actor-partner interdependence model. The findings confirm that becoming a parent, under normative and stressful circumstances, can lead to personal growth and parents of premature babies experience higher levels of growth than parents of full terms. Moreover, 1 month post-partum, actor effects were found for higher attachment anxiety and higher parental self-efficacy. Furthermore, personal growth at 1 month post-partum was found to be the strongest predictor of personal growth 5 months after childbirth. Five months post-partum, a positive partner effect was found for parental self-efficacy. Mothers reported higher growth than fathers only 5 months after the birth. It seems time plays an important role as to which variables contribute to personal growth. In the early stages of parenthood, personal growth is mostly an individual experience. Theoretical and clinical implications are discussed. Copyright © 2016 John Wiley & Sons, Ltd.