Prevention of preterm delivery
It is quite clear that although many methods have been
employed to predict preterm delivery, there is very little
success even in high-risk women. This has resulted in
developing measures to prevent preterm labor in high-risk
women and these include use of tocolytic drugs, antibiotics
and hormones (progesterone). Role of antibiotics has been
controversial. A recent randomised controlled trial concluded
that treatment of asymptomatic abnormal vaginal flora and
BV with oral clindamycin in early second trimester
significantly reduces the rate of late misarriage and spontaneous
preterm birth 25. Other studies have reported conflicting results
and there is wide variation in patient selection as well as the
antibiotics used. However, there is evidence from ORACLE
Trial that the use of antibiotics in patients with preterm prelabor
rupture of membranes (PPROM) reduces neonatal
morbidity, although there is no reduction in the incidence of
preterm birth 26. Therefore, it appears that use of antibiotics
may reduce the neonatal complications without having any
effect on the incidence of preterm births in patients with
PPROM. A recent Cochrane Review concluded that there is
no clear overall benefit from prophylactic antibiotics in preterm
labor with intact membranes on neonatal outcome 27.
A recent multi-centre randomized controlled trial concluded
that prophylactic use of 17-hydroxy progesterone caproate
significantly reduced the incidence of preterm labor 28. It
was not useful in suppressing established (active) preterm
labor. Further studies are needed to confirm these findings
and to determine the dosage, timing of commencement and
duration of treatment with progesterone.
Cervical cerclage has been tried to prevent preterm delivery
in women with ultrasonographic evidence of short cervix. A
recent survey among the obstetricians found a significant
uncertainty surrounding the decision whether to place a
cerclage and there is a considerable variation in the clinical
practice on its placement 29. A very recent multi-center
randomized controlled trial using cervical length of 15 mm
as a cut-off point concluded that use of Shirodkar suture in
women with short cervix does not substantially reduce the
risk of early preterm delivery 30. However, this study did
confirm that routine sonographic measurement of cervical
length at 22-24 weeks identifies a group at high risk (22% in
cerclage group vs 26% in control group) of early preterm
births (before 33 weeks). The effectiveness of emergency
cerclage in women with bulging membranes to prevent an
impending preterm birth is even more controversial. Fetal
survival rates of up to 89% have been reported 31. Some
studies reported a median duration of prolongation of
pregnancy of 4.5 weeks (range 1 day to 18 weeks) after this
procedure 32. Recently, cervical incompetence prevention