The longitudinal design of this study allowed an investigation of how factors measured at the time of the child's birth affected adolescent parenting 6 months after the child's birth. (academic.oup.com)
The overall design of the study was based on the quantitative research method. (eric.ed.gov)
The cross-sectional design of the study also means the authors can not confirm causality, i.e. a cause - and - effect. (sciencedaily.com)