Correspondence
Prevention of Preterm Birth
N Engl J Med 1998; 339:1858-1860December 17, 1998
- Article
To the Editor:
Goldenberg and Rouse (July 30 issue)1 correctly emphasize the need to define further the causes of the preterm birth syndrome in order to identify, treat, and prevent implicated processes in susceptible mothers. The authors' failure to recognize the potential benefits and cost savings of applying our present knowledge leads to unjustified nihilism and clinical complacency. Lamentably, they ignore or give short shrift to biologically based approaches that have already been demonstrated to be effective in large controlled trials or that are founded on the molecular mechanisms of human parturition.
These increasingly appreciated approaches include avoidance of multifetal pregnancies due to iatrogenic excesses of assisted reproduction; routine screening for and treatment of prevalent genitourinary microbial conditions, including sexually transmitted infections, group B streptococcal bacteriuria, and bacterial vaginosis2,3; nutritional approaches, including use of foods with n–3 essential fatty acids4; and endocrine–paracrine approaches focusing on the roles of corticotropin-releasing hormone and placental hormones in the signaling of parturition.5
The potential benefits of applying such aggregate knowledge to women at risk for preterm birth is increasingly recognized by providers, payers, and others.6 Studies of unselected women in Denver have shown that the population attributable risk is 22 percent for preterm birth related to bacterial vaginosis. Taken together, attributable risks for preterm birth associated with common genitourinary infections and bacterial vaginosis exceed 50 percent. Correspondingly, the application of these approaches reduced the rate of prematurity by half (from 18.8 percent to 9.8 percent) among women with bacterial vaginosis, with an estimated yearly savings of $2.5 million. These studies show that the greatest benefits of “screen and treat” approaches accrue to black mothers and to women with multiple infections, including bacterial vaginosis, trichomoniasis, and chlamydial infection.2
6 ReferencesJames A. McGregor, M.D., C.M.
Janice I. French, C.N.M.
Denver Health Medical Center, Denver, CO 802041
Goldenberg RL ,Rouse DJ . Prevention of premature birth. N Engl J Med 1998;339:313-320
Full Text | Web of Science | Medline2
McGregor JA ,French JI ,Parker R , et al. Prevention of premature birth by screening and treatment for common genital tract infections: results of a prospective controlled evaluation. Am J Obstet Gynecol 1995;173:157-167
CrossRef | Web of Science | Medline3
Thomsen AC ,Morup L ,Hansen KB . Antibiotic elimination of group-B streptococci in urine in prevention of preterm labor. Lancet 1987;1:591-593
CrossRef | Web of Science | Medline4
Olsen SF ,Sorenson JD ,Secher NJ , et al. Randomised controlled trial of effect of fish-oil supplementation on pregnancy duration. Lancet 1992;339:1003-1007
CrossRef | Web of Science | Medline5
McLean M ,Bisits A ,Davies J ,Woods R ,Lowry P ,Smith R . A placental clock controlling the length of human pregnancy. Nat Med 1995;1:460-463
CrossRef | Web of Science | Medline6
Maternal infectionsOb Gyn Malpract Prev 1997;4:73-77
To the Editor:
Goldenberg and Rouse state that several interventions are of no value in the prevention of premature birth. They consider the lack of a decline in premature births to support their conclusions. They seem unconcerned that the rate of premature birth actually increased by 17 percent during the period from 1981 through 1994.1 Artifacts of registration, as well as other factors that increase the rate of premature births, not only could have increased this rate but also could have obscured a reduction in the rate due to the same interventions Goldenberg and Rouse find to be ineffective.
Others have stated their concern about the increase in the rate of premature births.2 Improvements in ascertainment and the recording of gestational age on birth certificates may explain, in part, the rise in rates. Gestational age was not stated for 19.3 percent of live births in 1980, 4.3 percent in 1988,2 and only 0.87 percent in 1984.1 However, a clinical estimate of gestational age was permitted beginning in 1989, if the gestational age based on menstrual history was not available.3 Data on gestational age are most likely to be missing for women of low socioeconomic status, who are at the greatest risk for preterm delivery.2
In addition, multiple births have increased phenomenally since 1980, and over half of all multiple live births are premature.1 The rate ratio for multiple births increased by 35 percent during the period from 1981 through 1994. From 1981 through 1993, there was a 20 percent increase in preterm births to white mothers, which can be explained only in part by an increase in the proportion of multiple births. A slight increase in births to older women, who have a greater risk of premature delivery, would also have increased the rate of premature births among white women.3
Among the interventions that might prevent premature births, family planning, preconception care, and prevention of pregnancy were not mentioned by Goldenberg and Rouse. Yet according to a committee established by the Institute of Medicine to study the prevention of low birth weight, the active planning of pregnancy is one of the best methods available to prevent low birth weight and poor outcomes of pregnancy, especially for women who have had poor outcomes in the past.4
4 ReferencesSamuel Sepkowitz, M.D.
5300 North Meridian, Oklahoma City, OK 731121
Ventura SJ ,Martin JA ,Mathews TJ ,Clarke SC . Advance report of final natality statistics, 1994. Mon Vital Stat Rep 1996;44:Suppl:75-752
Berkowitz GS ,Papiernik E . Epidemiology of preterm birth. Epidemiol Rev 1993;15:414-443
Web of Science | Medline3
Ventura SJ ,Martin JA ,Taffel SM ,Mathews TJ ,Clarke SC . Advance report of final natality statistics, 1993. Mon Vital Stat Rep 1995;44:Suppl:1-884
Committee to Study the Prevention of Low Birthweight. Preventing low birthweight. Washington, D.C.: National Academy Press, 1985:119-31.
To the Editor:
I believe the review by Goldenberg and Rouse omits several important factors.
In an earlier study reported in the Journal, 1 intervals of less than nine months between pregnancies (a potentially modifiable factor) accounted for 85 percent of excess premature births in a population of black military families.
In another study,2 adolescent girls and women who reported physical abuse during pregnancy (20 percent of adolescents and 14 percent of adults) were more likely to begin prenatal care in the third trimester and had a 50 percent greater chance of delivering low-birth-weight infants than those who reported no physical abuse during pregnancy. Although I am not aware of prospective studies of interventions to identify abuse and reduce premature delivery, this is essential information to relay to those who provide prenatal care.
Although Goldenberg and Rouse cite the study by Kogan et al.3 in passing, it is worth noting that they found that advice on breast-feeding, alcohol use, smoking, illicit-drug use, diet, use of vitamins, and appropriate weight gain was effective in reducing premature delivery. All practitioners should provide these elements of prenatal care. Finally, in a study 4 not mentioned by Goldenberg and Rouse, in which lay health advisers or maternal role models were provided for pregnant teenagers, the delivery of low-birth-weight infants was reduced by about 33 percent as compared with that among controls.
4 ReferencesNeal Devitt, M.D.
La Familia Medical Center, Santa Fe, NM 87502-53951
Rawlings JS ,Rawlings VB ,Read JA . Prevalence of low birth weight and preterm delivery in relation to the interval between pregnancies among white and black women. N Engl J Med 1995;332:69-74
Full Text | Web of Science | Medline2
Parker B ,McFarlane J ,Soeken K . Abuse during pregnancy: effects on maternal complications and birth weight in adult and teenage women. Obstet Gynecol 1994;84:323-328
Web of Science | Medline3
Kogan MD ,Alexander GR ,Kotelchuck M ,Nagey DA . Relation of the content of prenatal care to the risk of low birth weight. JAMA 1994;271:1340-1345
CrossRef | Web of Science | Medline4
Heins HC Jr ,Nance NW ,Ferguson JE . Social support in improving perinatal outcome: the Resource Mothers Program. Obstet Gynecol 1987;70:263-266
Web of Science | Medline
Author/Editor Response
The authors reply:
To the Editor: If, as Lockshin states, “truly elegant clinical science defines syndromes with precision, delineates pathogenic mechanisms, and compares treatments in prospective randomized trials,”1 then much of the oblique evidence put forward by McGregor and French, Sepkowitz, and Devitt is lacking. McGregor and French have confused “unjustified nihilism” with a realistic assessment of the evidence and have confused “clinical complacency” with an intention to put practice on an evidence-based footing. Tellingly, on the basis of their single nonrandomized study, they advocate screening and treatment of all pregnant women for “prevalent genitourinary microbial conditions.” That a trial is large and controlled does not compensate for its being nonrandomized. We reiterate that the available evidence from randomized trials suggests that screening for and treatment of bacterial vaginosis are effective only for high-risk pregnant women. In the only published randomized trial conducted in a general population, screening for and treatment of bacterial (gardnerella) vaginosis were not beneficial.2 Likewise, data from randomized clinical trials do not confirm that the eradication of any other organism (or organisms) from the vagina, the cervix, or both will lead to a reduction in premature births.
We agree that bacteriuria should be treated in all pregnant women, that treatment of syphilis, gonorrhea, and chlamydia is indicated independently of prematurity, and that avoiding multifetal pregnancies is worthwhile. Supplementation with n–3 essential fatty acids, although associated with a four-day increase in the duration of pregnancy, was not associated with a reduction in preterm births.3 On the basis of this single Danish trial,3 are McGregor and French really recommending that every pregnant woman in the United States ingest 4 g of fish oil daily? We are also unaware of any data, however “increasingly appreciated,” supporting the statement that “endocrine–paracrine approaches” are effective in reducing preterm births.
We are perplexed by Sepkowitz's comment that we seem unconcerned about the rising prematurity rate. The one figure in our article documents the rise in the rate. We are also aware that women who plan their pregnancies, have longer intervals between pregnancies, and are not physically abused have fewer preterm births. However, observations describing associations do not validate interventions; randomized trials do, and interventions aimed at achieving these goals must be validated. A close reading of the article cited by Devitt on the content of prenatal care reveals that this study involved patients' recall of advice they received, and the outcome in question was low birth weight, not prematurity. Another article cited4 described a retrospective case–control study whose outcomes likewise did not include prematurity.
Standards for evaluating studies that form the basis for the practice of evidence-based medicine exist and should be used.5 The responses provoked by our review of the literature indicate a continued willingness on the part of some care givers to use interventions for the prevention of prematurity that fail to withstand, or have not been subjected to, rigorous scientific scrutiny.
5 ReferencesRobert L. Goldenberg, M.D.
Dwight J. Rouse, M.D.
University of Alabama at Birmingham, Birmingham, AL 35233-73331
Lockshin MD . Answers to the antiphospholipid-antibody syndrome? N Engl J Med 1995;332:1025-1027
Full Text | Web of Science | Medline2
McDonald HM ,O'Loughlin JA ,Vigneswaran R , et al. Impact of metronidazole therapy on preterm birth in women with bacterial vaginosis flora (Gardnerella vaginalis): a randomised, placebo controlled trial. Br J Obstet Gynaecol 1997;104:1391-1397
CrossRef | Medline3
Olsen SF ,Sorenson JD ,Secher NJ , et al. Randomised controlled trial of effect of fish-oil supplementation on pregnancy duration. Lancet 1992;339:1003-1007
CrossRef | Web of Science | Medline4
Heins HC Jr ,Nance NW ,Ferguson JE . Social support in improving perinatal outcome: the Resource Mothers Program. Obstet Gynecol 1987;70:263-266
Web of Science | Medline5
Task Force ratings. In: Preventive Services Task Force. Guide to clinical preventive services. Baltimore: Williams & Wilkins, 1996:861-2.
- Citing Articles (1)
Citing Articles
1
Richard M. Smith, Pamela A. Smith, Moira McKinnon, Michael Gracey. (2000) Birthweights and growth of infants in five Aboriginal communities. Australian and New Zealand Journal of Public Health 24:2, 124-135
CrossRef
