In response to several outbreaks of pertussis among newborns (in whom it is very serious and occasionally fatal), the CDC now recommends that pregnant women receive the Tdap vaccine during pregnancy. The purpose of this study was to investigate whether this new recommendation has any unintended side effects with respect to the risk of preterm birth. This was a retrospective study using data from the Kaiser Permanente health care consortium.
I was unable to obtain the actual data from this study; this is a simulated data set intended to resemble the findings of the original study for pedagogical purposes.
Delivery: The time of delivery (in weeks since conception)Vac: Indicator for whether the woman received the Tdap vaccine during pregnancytVac: The time that the woman received if vaccine, if applicableThe data is simulated, but was inspired by the following paper:
Kharbanda EO, Vazquez-Benitez G, Lipkind HS, Klein NP, Cheetham TC, Naleway A, Omer SB, Hambidge SJ, Lee GM, Jackson ML, McCarthy NL, DeStefano F, Nordin JD (2014). Evaluation of the Association of Maternal Pertussis Vaccination With Obstetric Events and Birth Outcomes. Journal of the American Medical Association, 312:1897-1904.