Prevention of Preterm Birth With a Pessary in Singleton Gestations

Preterm birth (PTB) is associated with over one million infant deaths annually worldwide. The
incidence of PTB in the United States is 11.5% with more than 500,000 deliveries occurring at
less than 37 weeks gestation annually. The rate of PTB in the United States increased to
12.8% in 2006, and remains high compared to almost all other developed countries, despite the
introduction of many public health and medical interventions designed to delay PTB. Weekly
treatment with 17-alpha hydroxyprogesterone caproate beginning at 16-20 weeks gestation has
been shown to significantly reduce the risk of PTB and is currently recommended for women who
experienced spontaneous PTB in a prior pregnancy. However, a strategy for the prevention of
spontaneous PTBs in which therapeutic intervention is restricted to women with a previous PTB
is likely to have a small effect on the overall rate of prematurity since only about 10% of
spontaneous PTBs arise in women with such a history. A major reduction in rates of mortality
and morbidity in premature babies will only be achieved with increased precision in the
identification of women at risk of spontaneous PTB and through the development of an
effective prevention for this complication. Transvaginal ultrasound measurement of cervical
length is a reliable screening test for prediction of PTB. Although treatment with vaginal
progesterone is effective in decreasing PTB in women with a short cervix, over 30% of women
still experience premature delivery and many women find daily administration of progesterone
to be challenging. Preliminary studies have suggested that use of an intravaginal pessary may
be effective in preventing PTB. If effective this approach would be particularly appealing
because of the wide availability of pessaries, ease of use, and low cost. Unfortunately,
existing studies are inadequate to confirm effectiveness; a well designed, properly powered,
prospective randomized trial is warranted prior to widespread implementation in clinical
practice. We propose such a trial to study the effectiveness of the pessary in decreasing the
incidence of PTB in an inner city Philadelphia population.