Preterm birth is the leading cause of neonatal morbidity and mortality. Several interventions are known for their use in preterm birth prevention, such as progesterone and a pessary. The Quadruple-P (QP) trial evaluates the effectiveness of progesterone versus pessary in singleton and twin pregnancies with a mid-trimester short cervix. Long term follow-up on the prenatal use of progesterone and pessary is scarce. With the Quadruple-P follow-up study we will assess the long-term effects of child (neuro-) development in children born to mothers who participated in the QP trial at 4-7 years of age, using internationally validated questionnaires.