<p>by Alexander J. Pritchard</p> The survival of offspring is an important determinant of fitness. A new study in PLOS Biology examines how early conceiving female mandrills (Mandrillus sphinx) with an infant have a higher probability of fetal loss, relative to other females. The survival of offspring is an important determinant of fitness. This Primer explores a new study in PLOS Biology examining how early conceiving female mandrills with an infant have a higher probability of fetal loss, relative to other females.