Prior Preterm Birth Research Articles

Bacterial vaginosis: review of treatment options and potential clinical indications for therapy.

We reviewed data on the treatment of bacterial vaginosis published from 1993 through 1996. For nonpregnant women, we recommend use of metronidazole (500 mg orally twice daily for 7 days), clindamycin vaginal cream (2%, once daily for 7 days), or metronidazole vaginal gel (0.75%, twice daily for 5 days) as the preferred treatment for bacterial vaginosis. For pregnant high-risk women (women with a prior preterm birth), the objective of the treatment is to prevent adverse outcomes of pregnancy, in addition to relief of symptoms. Thus, systemic therapy for possible subclinical upper tract infection as well as medication that has been studied in pregnant women are preferable. Therefore, we recommend metronidazole (250 mg orally three times a day for 7 days). For pregnant low-risk women (women without a prior preterm birth) with symptomatic disease, the main objective of the treatment is to relieve symptoms. We recommend metronidazole (250 mg orally three times a day for 7 days). Data do not support routine treatment of male sex partners.

Lack of prenatal care increases the rate of recurrent preterm delivery and health care costs when compared to university hospital-based prenatal care

Objective: To compare perinatal outcomes and total health care costs for patients with a previous history of preterm delivery (PTD) cared for in an inner-city university hospital house staff (HS) clinic vs pregnant patients who have not received any prenatal care (NPC). Study Design: We conducted a retrospective review of pregnant women with a history of PTD delivered at our institution between January 1994 and December 1996. Inclusion criteria were a history of at least one previous PTD. Prenatal care was given in a comprehensive setting in a teaching hospital. Exclusion criteria were infants with major malformations and multiple gestations. Data were obtained on maternal demographics and history of prenatal visits. Results: The study groups consisted of 96 HS and 53 NPC patients. There were no differences in maternal demographics, however, the number of prior preterm births was greater in the NPC group (1.59 vs 1.23, P = .003). The incidence of recurrent PTD (<34 weeks) was greater in the NPC group (49% vs 13%, P = <.001). The mean gestational age at time of delivery was decreased in the NPC group (33 weeks vs 37.2 weeks, P = <.001). The length of NICU stay was greater in the NPC group (15.6 vs 3.1 days, P = .001). The mean birth weight was less in the NPC group (2172 g vs 2786 g, P = <.001). The mean total mother-infant costs were significantly less in the HS group ($7,127 vs $18,047, P = .003). Even HS patients with only one prenatal visit had a significantly lower incidence of PTD (16% vs 75%, P = .04). Conclusions: Inner-city patients with a history of PTD who received even minimal prenatal care in a university HS clinic had a significantly lower incidence of recurrent PTD than those who had no prenatal care. Prenatal care also lowers total health care costs in women with a history of PTD. The coordinated multidisciplinary aspect of care provided at academic centers may have a positive impact on the problem of PTD.

The Preterm Prediction Study: Recurrence risk of spontaneous preterm birth

Objective: We sought to estimate the risk of spontaneous preterm birth in parous women by use of obstetric history, fetal fibronectin, and sonographic cervical length. Study Design: The probability of spontaneous preterm birth before 35 weeks' gestation was estimated from a logistic regression model with data from 1282 parous women analyzed according to gestational age at the most recent prior delivery (prior preterm birth at 18 to 26 weeks, 27 to 31 weeks, 32 to 36 weeks, and ≥37 weeks' gestation), fetal fibronectin status (positive = ≥50 ng/dl), and cervical length by percentile groups (≤10th = ≤25 nm, 10th to 50th = 26 to 35 mm, and >50th = >35 mm) measured at 22 to 24 weeks' gestation. Fibronectin and cervical length results were blinded for clinical care. Results: Among fetal fibronectin positive women with a prior preterm birth, the estimated recurrence risk of preterm birth <35 weeks' gestation was approximately 65% when the cervix was ≤25 mm, 45% when the cervix was 26 to 35 mm, and 25% when the cervix was >35 mm at 24 weeks' gestation. For fetal fibronectin negative women with a prior preterm birth, the recurrence risk was 25% when the cervix was ≤25 mm, 14% when the cervix was 26 to 35 mm, and 7% when the cervix was >35 mm. The risk of preterm birth was increased among women with a history of preterm delivery but was not influenced by the gestational age at delivery of the most recent preterm birth. Conclusion: The recurrence risk of spontaneous preterm birth varies widely according to fetal fibronectin and cervical length. Cervical length and fetal fibronectin results had distinct and significant effects on the recurrence risk of preterm birth. Predicted recurrence risk is increased by twofold to fourfold in women with a positive compared with a negative fetal fibronectin, and it increases as cervical length shortens in both fetal fibronectin–positive and fetal fibronectin–negative women. These data may be useful to care for women with a history of preterm birth and to design studies to prevent recurrent premature delivery. (Am J Obstet Gynecol 1998;178:1035-40.)

The preterm prediction study: the value of new vs standard risk factors in predicting early and all spontaneous preterm births. NICHD MFMU Network.

This study was undertaken to determine the relationship between fetal fibronectin, short cervix, bacterial vaginosis, other traditional risk factors, and spontaneous preterm birth. From 1992 through 1994, 2929 women were screened at the gestational age 22 to 24 weeks. The odds ratios for spontaneous preterm birth were highest for fetal fibronectin, followed by a short cervix and history of preterm birth. These factors, as well as bacterial vaginosis, were more strongly associated with early than with late spontaneous preterm birth. Bacterial vaginosis was more common--and a stronger predictor of spontaneous preterm birth--in Black women, while body mass index less than 19.8 was a stronger predictor in non-Black women. This analysis suggests a pathway leading from Black race through bacterial vaginosis and fetal fibronectin to spontaneous preterm birth. Prior preterm birth is associated with spontaneous preterm birth through a short cervix. Fetal fibronectin and a short cervix are stronger predictors of spontaneous preterm birth than traditional risk factors. Bacterial vaginosis was found more often in Black than in non-Black women and accounted for 40% of the attributable risk for spontaneous preterm birth at less than 32 weeks.

Management options in women with preterm uterine contractions: A randomized clinical trial

OBJECTIVE: Our purpose was to evaluate three management strategies and to assess pregnancy outcomes in women with preterm uterine contractions. STUDY DESIGN: Consenting women seen in our hospital triage area with preterm uterine contractions were randomly assigned to observation alone, intravenous hydration, or one dose of subcutaneous terbutaline sulfate (0.25 mg). Eligible women had a singleton gestation between 20 and 34 weeks, intact membranes, more than three contractions in 30 minutes, and a cervical dilation ≤1 cm and effacement <80%. Women who had progressive cervical change at <34 weeks were treated with intravenous tocolysis. Women with recurrent preterm uterine activity remained in their assigned group during subsequent triage visits. RESULTS: One hundred seventy-nine women were randomized: observation (56), hydration (62), and terbutaline (61). Women in these three groups were similar with respect to maternal age, race, parity, prior preterm births, gestational age at randomization, contraction frequency, and mean cervical dilatation. There were no intergroup differences in the mean days to delivery, the number of repeat triage visits, the incidence of preterm labor at <34 weeks, or the frequency of preterm deliveries at <34 weeks and <37 weeks. Women assigned to terbutaline had contractions stopped and were discharged earlier (terbutaline 4.1 ± 5.1 hours, observation 5.2 ± 5.3 hours, hydration 6.0 ± 5.7 hours; p = 0.006). No complications of therapy were observed. CONCLUSIONS: The use of intravenous hydration in the management of preterm contractions was of no benefit. The use of one dose of subcutaneous terbutaline resulted in the shortest length of triage stay but did not affect pregnancy outcome. (Am J Obstet Gynecol 1997;177:814-8.)

Antenatal steroid therapy before 33 weeks' gestation

OBJECTIVE: The purpose of this study was to determine those factors influencing contemporary antenatal steroid use in pregnancies delivered prior to 33 weeks of gestation. METHOD: We analyzed the clinical circumstances of 86 consecutive patients who delivered prior to 33 weeks of gestation and compared the 20 women who received dexamethasone prior to delivery with the remaining 66 untreated cases. RESULT: Known risk factors for preterm delivery (e.g. prior preterm birth, n = 17; prior admission and tocolysis during the index pregnancy, n = 15) did not discriminate between treated and untreated subsets. Premature membrane rupture ( 3 20 vs. 34 66 ; P < 0.01) and documented preterm labor ( 1 20 vs. 23 66 P < 0.01 ) were more common in the untreated cohort and a shorter mean interval from admission to delivery was also observed (2.8 vs 11.2 days). However, a full course of steroids would have been possible in 22 66 untreated women, since delivery was delayed for at least 36 h in these patients. CONCLUSION: These observations reflect the fact that many preterm births cannot be anticipated, even among hospitalized patients. We would therefore suggest that universal steroid treatment be considered for all women with documented preterm labor prior to 33 weeks of gestation. Initiation of steroid therapy at the referral center, (prior to maternal transport) should also be considered. Since both premature membrane rupture and early gestational age (24–28 weeks') confounded many of these cases, steroid use in patients with these circumstances should be reevaluated.

Predicting Prematurity: The Mammary Stimulation Test

The MST appears to have theoretical rationale, predictive utility, simplicity, safety, and low cost that suggests that its routine use in prematurity prevention may ultimately save significant health care dollars. Presently, the MST should be used as an adjunct to prenatal care until further and more definitive investigation has been conducted; however, it seems promising that the MST will provide some reassurance in patients with negative tests and signify patients that are at significant risk for premature delivery (positive MST). It is hoped that further investigation will validate the MST's use in prematurity prevention in order to help decrease the incidence of preterm delivery.

The perinatal impact of cocaine, amphetamine, and opiate use detected by universal intrapartum screening

Abstract Universal urine testing for cocaine, amphetamines, and opiates was performed on 1643 women admitted to an obstetric service for a 1-year period with 20.5% having positive results. There were 299 patients with positive toxicology results matched for race and discharge date with patients having negative toxicology and drug history. Significant differences in age, prior obstetric history, prenatal care, alcohol history, and smoking were noted between groups. There was a significant decrease in birth weight, head circumference, length, and gestational age for the drug-positive group, which was most marked in cocaine and multiple drug users. These differences persisted after we controlled for smoking, prenatal care, and prior preterm births. Differences in birth weight and head circumference remained after we controlled for gestational age. Rates of congenital anomalies and abruptio placental were similar between groups. Perinatal substance abuse is independently associated with growth retardation and prematurity. Multiple risk factors are frequently present, necessitating a comprehensive approach to prenatal care. (Am J Obstet Gynecol 1990;163:1535-42.)

Antenatal microbiologic and maternal risk factors associated with prematurity

In a prospective study of 202 women (gestational age 24 +/- 4 weeks), we evaluated possible influences of lower genital tract infection or bacterial conditions on obstetric outcomes, including preterm labor, preterm premature rupture of membranes, and preterm birth. The presence of bacterial vaginosis (18.7%) was associated with an increased risk of preterm labor (relative risk, 2.6; 95% confidence interval, 1.08 to 6.46). For women with bacterial vaginosis who also had Mobiluncus species morphotypes identified on Gram stain, the relative risk of preterm labor was 3.8 (95% confidence interval, 1.32 to 11.5). Presence of vaginal Mycoplasma hominis (10.8% of patients) was associated with both preterm labor (relative risk, 1.8; 95% confidence interval, 0.77 to 4.4) and preterm birth (relative risk, 5.1; 95% confidence interval, 1.45 to 17.9). Recovery of Staphylococcus aureus (3.0%) was associated with preterm labor (relative risk, 3.1; 95% confidence interval 1.12 to 8.7). Identification of two or more bacterial-linked abnormalities was also associated with preterm labor (relative risk, 3.3; 95% confidence interval, 1.44 to 7.58). An increased level of vaginal wash protease (greater than or equal to 10 trypsin units) (16%) was associated with preterm labor and was noted in 50% of women with preterm premature rupture of membranes. A history of prior preterm birth was the single best historical predictor of both preterm labor (relative risk, 3.6; 95% confidence interval, 1.92 to 6.83) and preterm birth (relative risk, 6.7; 95% confidence interval, 2.2 to 20.4). History of three or more abortions, antenatal urinary tract infection, and occurrence of medical complications during pregnancy also correlated with increased risk of preterm labor. These findings affirm and refine associations of various maternal reproductive tract infections with preterm labor, premature rupture of membranes, and birth, allowing for controlled treatment trials aimed at prevention of preterm birth.

Cervicovaginal microflora and pregnancy outcome: Results of a double-blind, placebo-controlled trial of erythromycin treatment

Available information suggests that some instances of preterm birth or premature rupture of membranes are associated with clinically unrecognized infection and inflammation of the lower uterine segment, decidua, and fetal membranes. Various cervicovaginal microorganisms have been recovered from these sites. Many of these microorganisms produce factors that may lead to weakening of the fetal membranes, release of prostaglandins, or both. This study evaluated the presence of various lower genital tract microflora and bacterial conditions in 229 women enrolled in a double-blind, placebo-controlled trial of short-course erythromycin treatment at 26 to 30 weeks' gestation to prevent preterm birth. Demographic, obstetric, and microbiologic parameters were prospectively evaluated. Premature rupture of membranes occurred less frequently (p<0.01) among women who received erythromycin (6%) versus placebo (16%). Preterm premature rupture of membranes also occurred less frequently, although not significantly (p = 0.3) in patients who received erythromycin (2%) versus placebo (5%). Erythromycin treatment significantly decreased the occurrence of premature rupture of membranes among women who were initially positive for Chlamydia trachomatis infection. Logistic regression analysis demonstrated that C. trachomatis (p = 0.05; odds ratio, 9), vaginal wash phospholipase C (p = 0.08; odds ratio, 6) and prior preterm birth (p = 0.007; odds ratio 17) were associated with increased risk of preterm birth. Bacterial vaginosis, Mycoplasma hominis, Ureaplasma urealyticum were not significantly associated with increased risk of preterm birth or preterm rupture of membranes. These findings support a role for selected lower genital tract microflora in preterm birth and premature rupture. Large controlled treatment trials of specific infections or conditions associated with preterm birth and premature rupture of membranes are required to confirm the value of antimicrobial treatments in prevention of microbial-associated preterm birth. (Am J Obstet Gynecol 1990;163:1580-91.)

The perinatal impact of cocaine, amphetamine, and opiate use detected by universal intrapartum screening

Universal urine testing for cocaine, amphetamines, and opiates was performed on 1643 women admitted to an obstetric service for a 1-year period with 20.5% having positive results. There were 299 patients with positive toxicology results matched for race and discharge date with patients having negative toxicology and drug history. Significant differences in age, prior obstetric history, prenatal care, alcohol history, and smoking were noted between groups. There was a significant decrease in birth weight, head circumference, length, and gestational age for the drug-positive group, which was most marked in cocaine and multiple drug users. These differences persisted after we controlled for smoking, prenatal care, and prior preterm births. Differences in birth weight and head circumference remained after we controlled for gestational age. Rates of congenital anomalies and abruptio placental were similar between groups. Perinatal substance abuse is independently associated with growth retardation and prematurity. Multiple risk factors are frequently present, necessitating a comprehensive approach to prenatal care. (Am J Obstet Gynecol 1990;163:1535-42.)

Antenatal microbiologic and maternal risk factors associated with prematurity

In a prospective study of 202 women (gestational age 24 ± 4 weeks), we evaluated possible influences of lower genital tract infection or bacterial conditions on obstetric outcomes, including preterm labor, preterm premature rupture of membranes, and preterm birth. The presence of bacterial vaginosis (18.7%) was associated with an increased risk of preterm labor (relative risk, 2.6; 95% confidence interval, 1.08 to 6.46). For women with bacterial vaginosis who also had Mobiluncus species morphotypes identified on Gram stain, the relative risk of preterm labor was 3.8 (95% confidence interval, 1.32 to 11.5). Presence of vaginal Mycoplasma hominis (10.8% of patients) was associated with both preterm labor (relative risk, 1.8; 95% confidence interval, 0.77 to 4.4) and preterm birth (relative risk, 5.1; 95% confidence interval, 1.45 to 17.9). Recovery of Staphylococcus aureus (3.0%) was associated with preterm labor (relative risk, 3.1; 95% confidence interval 1.12 to 8.7). Identification of two or more bacterial-linked abnormalities was also associated with preterm labor (relative risk, 3.3; 95% confidence interval, 1.44 to 7.58). An increased level of vaginal wash protease (?10 trypsin units) (16%) was associated with preterm labor and was noted in 50% of women with preterm premature rupture of membranes. A history of prior preterm birth was the single best historical predictor of both preterm labor (relative risk, 3.6; 95% confidence interval, 1.92 to 6.83) and preterm birth (relative risk, 6.7; 95% confidence interval, 2.2 to 20.4). History of three or more abortions, antenatal urinary tract infection, and occurrence of medical complications during pregnancy also correlated with increased risk of preterm labor. These findings affirm and refine associations of various maternal reproductive tract infections with preterm labor, premature rupture of membranes, and birth, allowing for controlled treatment trials aimed at prevention of preterm birth. (Ann J OBSTET GYNECOL 1990;163:1465-73.)