Previous Preterm Delivery Research Articles

The recurrence risk of the syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP) in subsequent gestations

Objective: Although it is an important clinical issue, accurate prediction of recurrence risk for the syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP) has been problematic because of limited patient experience. This study was undertaken to determine the likelihood that this form of severe preeclarnpsia-eclampsia or any other hypertensive disorder would occur in a subsequent pregnancy.Study Design: An extensive retrospective analysis of medical records and patient follow-up regarding subsequent pregnancy outcome were undertaken for the 481 patients with HELLP syndrome managed at this tertiary medical center between Jan. 1, 1980, and Oct. 30, 1991. The Mississippi three-class system was used to define severity of disease on the basis of the lowest observed perinatal platelet count (class 1 ≤ 50,000/μl, class 2>50,000/μl to ≤ 100,000//μl, and class 3>100,000//μl to ≤ 150,000/μl).Results: Subsequent gestations (n = 195) occurred in 122 of 481 patients. Evaluable data were available for analysis in 161 of 195 possible pregnancies. Seventy-eight (48%) pregnancies were complicated by some type of hypertensive disorder, 44 (27%) of which had class 1, 2, or 3 HELLP syndrome. Non-HELLP preeclampsia-eclampsia was detected in 25 subsequent gestations (15%). Thus the total frequency of preeclampsia was 69 in 161 (43%). If the data for class 3 HELLP are completely excluded from the analysis, 81 subsequent evaluable and viable gestations were identified, 19 pregnancies with preeclampsia-eclampsia (23%) and 15 patients with HELLP syndrome (19%), for a total recurrence rate of 42%. Subsequent HELLP gestations were frequently delivered abdominally (64%) on average 2 weeks later than the index pregnancy (32.6 ± 5.0 weeks versus 34.7 ± 5.3 weeks). Delivery at < 32 weeks conferred a high risk (61 %) for a similar preterm delivery in a subsequent gestation.Conclusion: The risk of recurrence of the HELLP syndrome in our population is 19% to 27%. When data from all pregnancies with all farms of preeclarnpsia are considered, the risk of recurrence for any type of preeclampsia-eclampsia is 42% to 43%. A previous preterm delivery is a very high risk factor for recurrence of prematurity with preeclampsia-eclampsia.

Previous pregnancy outcomes and subsequent risk of preterm rupture of amniotic sac membranes.

To test the hypothesis that previous unfavourable pregnancy outcomes increase the risk for premature birth, with (PP) or without (PTB) premature rupture of the amniotic sac (PROM) at the index pregnancy and that multiple undesirable outcomes increase risk. Case control study. Two university hospitals. Four hundred sixty-three women aged 15 to 45 years who were delivered preterm PROM, full term PROM and preterm without PROM matched with 463 women who delivered full term. All women included in the study had at least one previous pregnancy. Odds ratio of previous adverse pregnancy outcome among index cases. Compared with controls, PP cases had odds ratios of 95 for previous preterm birth, 186 for abortion and prematurity and 158 for fetal loss, abortion/prematurity after controlling for confounding variables. Compared with controls, PTB cases had an odds ratio of 96.5 for previous preterm delivery, 84 for abortion and prematurity, and 320 for fetal loss/abortion and prematurity after controlling for confounding variables. Previous preterm delivery, abortion and prematurity and fetal loss/abortion and prematurity all increase risk for subsequent preterm birth with or without PROM.

Risks for premature rupture of amniotic membranes.

The objective of this study was to test the hypothesis that diverse risk variables including infections during the index pregnancy independently increase the risk of preterm premature rupture of amniotic membranes (PROM) and preterm delivery without PROM. A case-control design was used to study women 15-45 years old who had preterm PROM, full-term PROM or preterm without PROM and were singly matched by age race and parity to controls who delivered full-term infants. The odds for preterm PROM was 6.0 times that of controls among women with intra-amniotic infection, 3.7 times among those with urinary tract and 7.6 times among women with gonorrhoea infections after controlling for the effects of exposure to cigarette smoke, having previous preterm and full-term PROM deliveries and antepartum bleeding that independently increased the odds. The odds for preterm births without PROM was 4.8 times that of controls among women with a previous preterm PROM birth, was significantly increased among those exposed to cigarette smoke or having antepartum bleeding, but not among those exposed to chlamydia infection. Even after adjusting for concomitant risk factors, women with preterm PROM births were more likely than their matched controls to have had infections.

Prematurity Prevention: Who is at Risk?

Previous preterm birth, previous preterm labor, regular uterine activity, uterine distention, and preterm cervical change are factors that are most often present in patients treated for preterm labor or in patients delivered prematurely. In addition to their frequency, their severity is also the highest in terms of patient risk. These factors usually are easily identified, and an appropriate management plan can be implemented to decrease the incidence of preterm births or to at least increase the fetal time in utero. Antenatal bleeding, chronic urinary tract infections, smoking, and maternal age are also associated with preterm labor. Although these factors are not present as often, they have the potential to precipitate preterm labor and preterm delivery. When they are identified, it is necessary to utilize the appropriate therapeutic measures commensurate to the number and/or the degree of the risk factors. Vaginal microbiology, maternal hematocrit, substance abuse, and coitus are factors that are undergoing active investigation in regards to precipitating preterm birth. They are frequently seen in normal pregnancies, but recently have been associated with a greater likelihood for preterm labor and preterm birth. Unequivocal evidence of this association is currently unavailable; however, more and more investigations are reporting a significant association of these factors with preterm births. The relative degree of risk and the optimal management plans for dealing with these factors also await further definition and refinement. We know that there is no surveillance technique, or combination of techniques, that will identify all patients who will eventually deliver preterm. In many reports, despite the diligent attention to many of the earlier-mentioned risk factors, almost two of three patients who have delivered preterm had no easily identified risk factor. In addition, many patients delivered preterm report no perception of uterine activity (Garbaciak JA, Desch C, unpublished data). Other investigators have concluded that because most of the potentially preventable births occur in groups that present with marked cervical dilatation, it may be difficult to lower significantly the preterm birth rate below the current levels. Despite the sometimes dismal outlook regarding the prevention of preterm labor and delivery, the multiple investigators that have reported certain successes in their study populations should give us hope and encourage us to apply those techniques that appear appropriate and effective in our individual populations and patients. We can see and measure successful outcomes only if we are willing to look and aggressively to attempt to decrease untoward perinatal events.(ABSTRACT TRUNCATED AT 400 WORDS)

Does It Prevent Prematurity?

PREVENTION of premature births is the most important challenge in obstetrics. Recently a device for monitoring uterine activity at home (the Genesis Home Uterine Activity Monitor [HUAM] system, Tokos Medical Group), coupled with daily contact between patients and medical personnel, was reported to prevent premature births at an average cost per patient of over $5,000.1 The Food and Drug Administration recently approved this system for the early detection of preterm labor in women who had had a previous preterm delivery. The agency did not approve this system of care for the prevention of premature births, however, and has made it . . .

The incidence of preterm labor and specific risk factors

A retrospective review of patients at high risk for preterm delivery because of twin gestation, uterine malformation, incompetent cervix, or previous preterm delivery was carried out to assess the rates of preterm labor and spontaneous preterm birth. Among the 119 patients with multifetal gestation, 46% had preterm labor and 36% delivered before 37 weeks' gestation. In the 58 patients with an anomalous uterus, the rate of preterm labor was 19%, and 14% had early deliveries. Of those with incompetent cervices (115), one-fourth had preterm labor and 17% had an early birth. When a history of one or more preterm deliveries was present, the preterm labor rate ranged from 41-68%, with an early delivery rate of 30-47%. Prophylactic tocolytic therapy did not prolong gestations significantly. Maternal smoking did not have an adverse effect on the incidence of preterm labor except in twin pregnancies, for which early delivery was more likely. The percentages for preterm delivery are slightly lower than those found in the literature; this may be attributable to improvement in preterm birth prevention efforts including patient education, more frequent examinations, home uterine activity monitoring, and daily nursing contact.

Perinatal outcome in triplet versus twin gestations

The present study was conducted to determine whether triplet pregnancies are associated with a significantly worse perinatal outcome than twin pregnancies. Maternal and neonatal outcome was evaluated in 15 triplet and twin pregnancies that were matched for maternal age, race, type of medical insurance, delivery mode, parity, and history of previous preterm delivery. Preterm labor occurred significantly more often in triplet than in twin gestations (80 versus 40%), as did preterm delivery (87 versus 26.7%). Triplets had a significantly lower mean birth weight (1720 versus 2475 g) and gestational age at delivery (33 versus 36.6 weeks). In addition, 53.3% of triplet pregnancies but only 6.7% of twin pregnancies had one or more neonates with intrauterine growth retardation. Discordancy also occurred more frequently in triplets than in twins (66.7 versus 13.3%). The mean averaged neonatal hospital stay was significantly higher in triplets (29 versus 8.5 days), and triplets had a fivefold increased risk of requiring neonatal intensive care as compared with twins. However, there were no significant differences between the groups in maternal morbidity or major neonatal complications such as respiratory distress syndrome or intraventricular hemorrhage. We believe that these data will be useful in counseling patients with respect to the anticipated perinatal outcome of triplet pregnancies.

Previous obstetric history and subsequent preterm delivery in Greece

A total population sample of 6524 multigravid women who were certain of the date of their last menstrual period was obtained from the population-based Greek National Perinatal Survey of April 1983. The sample was used to determine the associations between features of the maternal obstetric history and preterm delivery. There were significant associations between preterm delivery and previous fetal losses, whether early (miscarriages and/or induced abortions) or late (stillbirths). For mothers who had experienced miscarriage(s), induced abortion(s) or stillbirth(s) the odds ratios were 1.40, 1.36 and 1.15, respectively, compared with mothers without any fetal loss. The odds ratio increased substantially with the increasing number of losses and reached 5.60 for the small group of mothers who had had prior miscarriage, termination and stillbirths. The results changed very little when the socioeconomic characteristics of the family were taken into account.

Intrauterine growth retardation and preterm delivery: Prenatal risk factors in an indigent population

Prenatally ascertained risk factors for low birth weight were evaluated in a population of 17,000 indigent women for their specific effect on intrauterine growth retardation and on the rate of preterm delivery. In a univariate analysis, intrauterine growth retardation occurred more frequently in women who were black, single, primiparous, 30 years old, short, thin, had a previous preterm delivery, consumed alcohol, took drugs, or gained limited weight. Preterm delivery occurred significantly more frequently in women who were black, single, thin, 30 years old, had less than a twelfth grade education, or gained limited weight. In logistic regression analyses, race, parity, maternal age, a history of preterm delivery, smoking, short stature, low weight, and low weight gain remained significant risk factors of intrauterine growth retardation. Of these factors, smoking, short stature, low weight, and low weight gain showed the greatest correlation. Factors significantly related to preterm delivery included black race, single marital status, younger or older ages, previous preterm delivery, smoking, low weight, and very low or high weight gain. A previous preterm delivery and very low maternal weight had the greatest correlation. Identification of specific risk factors of both intrauterine growth retardation and preterm delivery should aid in the development of strategies to reduce the prevalence of these conditions. (AM J OBSTET GYNECOL 1990;162:213-8.)

Prenatal Ultrasound: Are Socially Disadvantaged Groups Afforded Equal Access?

A retrospective cohort study was conducted of the patterns of ultrasound use during pregnancy for all single live births (n = 2542) delivered at a major teaching hospital in one calendar year. Extent of maternal education was inversely correlated with the probability of receiving a prenatal ultrasound examination (p less than 0.001). Clinic patients were more likely to receive prenatal ultrasound examinations than were private patients (p less than 0.001). Blacks were more likely than whites to receive prenatal ultrasound examinations (p less than 0.001). Short duration of prenatal care, inadequate weight gain during pregnancy, and history of previous pre-term delivery were all associated with an increased probability of receiving a prenatal ultrasound examination (p less than 0.001).

Risk factors for preterm premature rupture of fetal membranes: A multicenter case-control study

To assess the association between women with preterm premature rupture of membranes and 41 potential risk factors, we conducted a case-control study in six United States tertiary perinatal centers. The study involved completion of a comprehensive questionnaire for 341 women with preterm premature rupture of membranes in singleton pregnancies from 20 to 36 weeks' gestation and 253 control women matched for maternal age, gestational age, parity, clinic or private patient status, and previous vaginal or cesarean delivery. Univariate analysis revealed 11 variables associated with a significantly (p less than 0.05) increased risk of preterm premature rupture of membranes. After multiple logistic regression analysis, three variables remained in the model as independent risk factors: antepartum vaginal bleeding in more than one trimester (odds ratio 7.4; 95% confidence interval, 2.2, 25.6), current cigarette smoking (odds ratio, 2.1; 95% confidence interval, 1.4, 3.1), and previous preterm delivery (odds ratio, 2.5; 95% confidence interval, 1.4, 2.5). Cessation of cigarette smoking by pregnant women may reduce the risk of preterm premature rupture of membranes. Further study is necessary to determine the nature of the relationship between antepartum vaginal bleeding and preterm premature rupture of membranes.

Intrauterine growth retardation and preterm delivery: prenatal risk factors in an indigent population

Prenatally ascertained risk factors for low birth weight were evaluated in a population of 17,000 indigent women for their specific effect on intrauterine growth retardation and on the rate of preterm delivery. In a univariate analysis, intrauterine growth retardation occurred more frequently in women who were black, single, primiparous, less than 17 or greater than 30 years old, short, thin, had a previous preterm delivery, consumed alcohol, took drugs, or gained limited weight. Preterm delivery occurred significantly more frequently in women who were black, single, thin, less than 17 or greater than 30 years old, had less than a twelfth grade education, or gained limited weight. In logistic regression analyses, race, parity, maternal age, a history of preterm delivery, smoking, short stature, low weight, and low weight gain remained significant risk factors of intrauterine growth retardation. Of these factors, smoking, short stature, low weight, and low weight gain showed the greatest correlation. Factors significantly related to preterm delivery included black race, single marital status, younger or older ages, previous preterm delivery, smoking, low weight, and very low or high weight gain. A previous preterm delivery and very low maternal weight had the greatest correlation. Identification of specific risk factors of both intrauterine growth retardation and preterm delivery should aid in the development of strategies to reduce the prevalence of these conditions.

Evaluation of risk scoring in a preterm birth prevention study of indigent patients

A total of 4591 indigent patients were scored for risk of preterm labor and birth by the Creasy et al. scoring system and delivered at greater than or equal to 20 weeks' gestation. Of 462 preterm deliveries (less than 37 weeks), only 39.6% were contributed by the 18.1% of patients who scored at high risk (score greater than or equal to 10). Of the 44 risk factors in the scoring system, 25 were not statistically significant by univariate chi 2 analysis. The spontaneous preterm birth rate was 8.0%. The positive predictive value of the Creasy et al. system was 18.3%. With multiple logistic analyses we excluded infrequent risk factors and identified five factors that remained significant (prepregnancy weight less than 45.5 kg, black race, single marital status, one preterm labor and delivery, preterm labor, and delivery greater than or equal to 2). With these five risk factors we created an equation that allowed identification of 12% of patients at high risk of preterm delivery with a positive predictive value of 21.9%. Because of the importance of previous preterm delivery, risk scoring of primigravid patients is of limited value.

Risk factors for prematurity and premature rupture of membranes: A prospective study of the vaginal flora in pregnancy

Prematurity remains a major cause of perinatal mortality in the United States. Some research has indicated that infectious agents play a role in either initiating preterm labor, causing premature rupture of the membranes, or preventing tocolysis. This study attempted to determine if the presence of various vaginal pathogens in early pregnancy was associated with the subsequent development of premature rupture of membranes or preterm labor. We found that among 233 evaluable patients those with Trichomonas vaninalis were significantly more likely to have premature rupture of the membranes (p < 0.03), and those with Bacteroides sp. were more likely to be delivered of their infants before 37 weeks (p < 0.03) and to have infants weighing less than 2500 gm (p < 0.05). Those with Ureaplasma urealyticum more frequently began preterm labor (p < 0.05). Preterm premature rupture of the membranes was found significantly more often among patients with Bacteroides sp. Stepwise multiple logistic regression analysis indicated that those associations were not related to the number of previous abortions, deliveries, or preterm deliveries or to maternal age. We conclude that microbiologic screening in early pregnancy may aid in the assessment of patient risk for preterm delivery.

AN EPIDEMIOLOGIC STUDY OF PRETERM DELIVERY

A case-control study of the epidemiology of preterm delivery was undertaken at Yale-New Haven Hospital in Connecticut during 1977. The study population consisted of 175 mothers of singleton preterm infants and 313 mothers of singleton term infants. Significant risk factors of a preterm delivery included low socioeconomic status; low pregravid weight; inadequate weight gain during the pregnancy; a previous preterm delivery; a history of infertility problems; an induced abortion terminating the previous pregnancy; vaginal spotting or light bleeding during the pregnancy; antepartum hemorrhage and abnormal placental implantation; lack of leisure-time physical activities during the pregnancy; alcohol consumption prior to the third trimester of pregnancy; and negative attitudinal expression toward the pregnancy.

Risk of pre-term delivery in patients with previous pre-term delivery and/or abortion.

Patients with a history of two or more pregnancies which ended spontaneously before 37 weeks gestation had an increased risk of spontaneous pre-term labour and delivery in future pregnancies. This increased risk related mainly to previous second trimester abortions and not to previous first trimester abortions. Patients with one previous spontaneous pre-term labour and delivery had a 37 per cent risk, and those with two or more pre-term deliveries a 70 per cent risk of again delivering pre-term. There appeared to be no beneficial effect of cervical suture on the incidence of pre-term delivery in these patients.