The cross-sectional and retrospective nature and small sample sizes of most studies limit external validity of the results. Retrospective studies require mothers to remember past symptoms, recalling a previous experience is prone error as mothers tend to forget and small sample sizes resulted in non-significant findings. Most of the studies, except one RCT, utilized convenience sampling and participants were mainly from developed countries with the study mainly set in either major tertiary hospitals or the Internet based databases. Caution is needed when applying these findings to low-resource settings and to mothers in primary or secondary level hospitals. Prospective longitudinal research is needed to examine the trajectory of perinatal PTS symptoms in mothers from both high and low income countries. These findings, engage more prospective longitudinal data collection, especially for Malawi, which has the highest preterm birth rate in the world.