Prevention Strategies

The prevention of preterm birth has been attempted by the use of interventions aimed at each of the risk factors described in the previous chapters, largely without success (Table 9-5).


TABLE 9-5 Summary of Studies of Medical Interventions to Prevent Preterm Birth

Risk Factor or Popu!

tion Studied Interventions Tested in RCT Outcome


Nutritional deficiencies

Nutritional supplements Vitamins C and E

No benefit, vitamin C-CPEP Trial, inadequate data

Rumbold and Crowther, 2005

Prior preterm birth and bacterial vagi-nosis

Antibiotics during pregnancy Mixed results

McDonald et al., 1994; Carey et al., 2000; Hauth et al., 1995; Carey, 2000; Lamont et al., 2003; Guise et al., 2001; Okun et al., 2005

Prior preterm birth Cervical cerclage

Mixed but mostly negative

Berghella et al., 2005; see also Odibo et al., 2003; Harger, 2002; Owen et al., 2003; Bachmann et al., 2003; Belej-Rak et al., 2003; Drakeley et al., 2003

Positive risk score

Education and self-detection of contractions

No benefit

Collaborative Group on Preterm Birth Prevention, 1993; Mueller-Heubach and Guzick, 1989

Prior preterm birth (singletons)

Progesterone suppository" and intramuscular 17a-hydroxyprogesterone caproate4

33 percent reduction in preterm birth rates

Da Fonseca et al., 2003; Meis et al., 2003; see also meta-analyses by Dodd et al., 2005; Sanchez-Ramos et al., 1999

Prior preterm birth and increased contractions (singletons)

Positive vaginal swab cultures for various organisms

Nurse contact and/or contraction monitor

Antibiotics during pregnancy

No benefit meta-analyses

No benefit; mixed if also positive cultures VIP

CHUMS, 1995; Dyson et al., 1998

Brockelhurst et al., 2000; Gibbs et al., 1992; Carey and Klebanoff, 2003; Riggs and Klebanoff, 2004; Klebanoff et al., 2005

Positive fetal fi-bronectin

Metronidazole and erythromycin at 24-27 wk

No benefit; some (?) Andrews et al., 2003 increased risk in antibiotic group

Prior PTD and positivity for fetal fibronectin

Metronidazole at 24-27 wk

Increased preterm Sheenan et al., 2006

birth in metronidazole group

Short cervix without a prior PTD

Cerclage (usually with antibiotics at surgery)

Mixed results, but Rust et al., 2001; Berghella et al., mostly negative 2005

Short cervix in women with prior preterm birth Prior preterm birth

Cerclage (usually with antibiotics at surgery)

Antibiotics before next pregnancy

Mixed results

No benefit

Berghella et al., 2005

Andrews, 2006



Risk Factor or Popul tion Studied

Interventions Tested in RCT



Preterm labor in current pregnancy

Nurse contact or contraction monitor

No benefit

Berkman et al., 2003; Iams et al., 1990; Brown et al., 1999; Nagey et al., 1993

Preterm labor in current pregnancy

Maintenance tocolysis (oral and subcutaneous infusion)

No benefit

Berkman et al., 2003. Sanchez-Ramos et al., 1999

Singletons at risk and Twins

Prophylactic bed rest

Inadequately studied (Sosa et al., 2004); no benefit (Goldenberg et al., 1994)

Sosa et al., 2004; Goldenberg et al., 1994


Prophylactic tocolytic drugs

No benefit

Marivate et al., 1977

Twins and increased contractions

Nurse contact or contraction monitor

No benefit

Dyson et al., 1998

NOTE: RCT = randomized controlled trial; PTD = preterm delivery.

NOTE: RCT = randomized controlled trial; PTD = preterm delivery.

Most interventions are based on the traditional medical model of identifying and correcting each potential cause or risk factor for preterm birth, with the expectation that the rate of pre-term births would decline in accordance with the contribution of that factor to the prematurity rate. Intervention trials have thus addressed the early identification of preterm labor through patient education, pharmacologic suppression of uterine contractions, antimicrobial therapy of vaginal microorganisms, the use of cerclage sutures to bolster the cervix, reduction of maternal stress, improved nutrition and improved access to prenatal care, and reduced physical activity. Some trials enrolled women with the risk factor in question without regard to obstetric history (e.g., antibiotics for women with a positive culture for a genital microorganism), whereas others were limited to women with a prior preterm delivery (e.g., the European cerclage trials or the recent progesterone supplementation studies [Da Fonseca et al., 2003; Meis et al., 2003]). Although successful elimination of single risk factors has been accomplished, for example, by antibiotic treatment of a targeted vaginal organism or suppression of contractions with tocolytic compounds (labor-inhibiting agents), successful removal of a risk factor has not produced a decrease in preterm birth rates. In fact, the overall rate of preterm birth has continued to increase.

Future studies of the etiology and means of prevention of preterm birth should recognize the implications of these findings to develop a more sophisticated understanding of preterm birth as a syndrome in which multiple physiological pathways operate simultaneously to initiate pre-term parturition. The common complex disorder model currently used in cardiovascular disease and neoplasia may be an appropriate replacement for the more unifactorial approach that has dominated the last two decades of research. The findings of studies of prevention strategies described below reinforce this recommendation.

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  • micah
    What is the full reference name of odibo et al. 1990?
    6 months ago

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