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PubMed2004

Cervical cerclage for prevention of preterm delivery in women with short cervix: randomised controlled trial.

BACKGROUND: Cervical cerclage has been widely used in the past 50 years to prevent early preterm birth and its associated neonatal mortality and morbidity. Results of randomised trials have not generally lent support to this practice, but this absence of benefit may be due to suboptimum patient selection, which was essentially based on obstetric history. A more effective way of identifying the high-risk group for early preterm delivery might be by transvaginal sonographic measurement of cervical length. We undertook a multicentre randomised controlled trial to investigate whether, in women with a short cervix identified by routine transvaginal scanning at 22-24 weeks' gestation, the insertion of a Shirodkar suture reduces early preterm delivery. METHODS: Cervical length was measured in 47?123 women. The cervix was 15 mm or less in 470, and 253 (54%) of these women participated in the study and were randomised to cervical cerclage (127) or to expectant management (126). Primary outcome was the frequency of delivery before 33 completed weeks (231 days) of pregnancy. FINDINGS: The proportion of preterm delivery before 33 weeks was similar in both groups, 22% (28 of 127) in the cerclage group versus 26% (33 of 126) in the control group (relative risk=0.84, 95% CI 0.54-1.31, p=0.44), with no significant differences in perinatal or maternal morbidity or mortality. INTERPRETATION: The insertion of a Shirodkar suture in women with a short cervix does not substantially reduce the risk of early preterm delivery. Routine sonographic measurement of cervical length at 22-24 weeks identifies a group at high risk of early preterm birth.

Adult↗

PubMedDate not supplied

Antioxidant vitamin levels in term and preterm infants and their relation to maternal vitamin status.

BACKGROUND: Lipid peroxidation plays a vital role in the pathogenesis of many neonatal complications. Preterm babies are especially predisposed to lung diseases and retinopathy, probably due to a deficiency in their antioxidant systems. Vitamins E, A, and C are part of the natural antioxidant defense systems. We aimed to determine the levels of vitamins E, A, and C in maternal and cord blood plasma of term and preterm infants and to investigate the relationships between these levels. METHODS: In the present study we determined vitamin E, A, and C levels in the umbilical cord blood of term (n = 30) and preterm (n = 22) infants and their mothers by HPLC. Blood samples were taken during delivery. RESULTS: Levels of lipid soluble antioxidant vitamin E and A in cord blood were lower than maternal values (p <0.01, p <0.05, respectively). Conversely, the level of water-soluble vitamin C was higher in cord blood than in maternal level (p <0.05). Significantly higher levels of vitamins E, A, and C were found in term babies as compared with those born preterm (p <0.05). CONCLUSIONS: There was a positive correlation between maternal and cord blood levels of vitamins E and A (r = 0.775, r = 0.725, respectively). In conclusion, preterm babies have fewer lipid-soluble antioxidant vitamins in their serum compared to term infants. Therefore, it is possible to postulate that preterm infants are more susceptible to oxidative stress.

Antioxidants↗

PubMed2002

Immunogenicity of hepatitis B vaccine in preterm and full term infants vaccinated within the first week of life.

The immunogenicity of a Hepatitis B vaccine was evaluated in 110 neonates (57 full term and 53 preterm) born to Hepatitis B surface antigen (HBsAg) negative mothers. Three 10 microg doses of recombinant Hepatitis B vaccine were administered: the first dose within the first week of life; the second between 1 and 2 months; and the third at 5-7 months of age. Anti-HBs antibody titres were measured 3 months after the third dose. The seroconversion rate in preterm infants (77%; 95% CI=64.7-87.1) was significantly lower than in full term infants (98%; 95% CI=91.6-99.9) while the mean anti-HBs titres among those infants that did seroconvert was lower in preterm (186.6 mIU ml(-1)) than in full term infants (537.5 mIU ml(-1)). More full term than preterm infants showed titres greater than 100 mIU ml(-1) (71.9 and 41.5%, respectively). We conclude that the administration of a recombinant Hepatitis B vaccine shortly after birth is less immunogenic in preterm infants weighing <1800 g at birth than in full term infants. Currently accepted recommendations for post exposure perinatal prophylaxis may be inadequate to protect preterm infants.

Female↗

PubMedDate not supplied

High cord blood IL-10 levels in preterm newborns with respiratory distress syndrome.

BACKGROUND: The development of respiratory distress syndrome (RDS) is closely related to fetal immaturity, although the participation of inflammatory mechanisms also seems to be likely. We previously reported high interleukin-10 (IL-10) levels in cord blood from preterm infants. In the present study, we investigate the possible role of IL-10 and IL-12 in preterm newborns with RDS, a disease that is also closely related to gestational age. PATIENTS AND METHODS: Cord blood levels of IL-10 and IL-12 (p70 + p40) were determined by ELISA in 20 preterm infants who later developed RDS, in 21 preterm infants without RDS and in 31 full term newborns. In 11 patients follow-up samples could be also obtained between 2 and 14 days of life. RESULTS: Preterm infants with RDS showed higher IL-10 (27 vs 10.8 pg/mL; p: 0.0003) and lower IL-12 (188 vs 384; p: 0.002) levels in cord blood than premature infants without RDS and full term newborns (IL-10: 3.2 pg/mL, p: 0.0001; IL-12: 352 pg/mL; p: 0.002). The differences remained statistically significant after correction for the effect of gestational age between both preterm groups. CONCLUSIONS: The results obtained may be related to an immature cytokine response in premature infants, but the IL-12/IL-10 imbalance found in our patients also supports the hypothesis that inflammation plays a role in RDS.

Biomarkers↗

PubMed2004

Preterm birth rates in Avon County, England, and urban Ukraine.

OBJECTIVE: We compared rates of total and spontaneous preterm birth in Avon County, England and urban Ukraine to explore whether adverse conditions in the former eastern bloc influenced the preterm rate. STUDY DESIGN: Women who had last menstrual period (LMP) in a specified time window were recruited from geographically defined areas. Data were gathered between 1992 and 1995, using maternal questionnaires and medical record abstraction, with comparable methods in both sites insofar as possible. There were 13731 births in Avon and 3087 in Ukraine. Rates of total and spontaneous preterm births were compared, taking account of maternal characteristics and other relevant variables. RESULTS: The total preterm birth rates were similar (5.9%, Ukraine; 5.5%, Avon) but the spontaneous preterm rate was about 60% higher in Ukraine (5.0% versus 3.1%). Maternal characteristics and measurement differences did not explain the discrepancy. CONCLUSION: The difference in the spontaneous preterm rates may reflect differences in obstetrical management resulting from shortages of medical supplies and equipment in Ukraine.

Adolescent↗

PubMed1997

Rapid fetal fibronectin swab-test in preterm labor patients treated by betamimetics.

OBJECTIVE: A preliminary study to examine the value of a rapid fetal fibronectin swab-test used as a bedside test in the prognosis of preterm labor. STUDY DESIGN: Women presenting with preterm labor and intact membranes and less than 3 cm dilated were enrolled in a single referral center. Cervicovaginal swabs were assessed for the presence or absence of fetal fibronectin by means of a rapid monoclonal antibody assay the positivity of which was revealed by a colorimetric reaction. Results were compared with uterine contractions frequency, Bishop cervical score, duration of tocolysis and interval to delivery. The predictive value of fetal fibronectin test for delivery within 7, 14 or 21 days from sampling and before 32 and 37 weeks' of gestation was assessed in the two groups. RESULTS: Among 124 eligible patients, 19 presented with a positive fibronectin test and 105 with a negative one. Gestational age at sampling, Bishop cervical score and duration of tocolysis were identical in the two groups. The number of contractions was significantly lower and gestational age at delivery was significantly higher in the fibronectin negative group. Fetal fibronectin in cervicovaginal secretions has a high sensitivity (89%) for delivery within 7 days. Absence of fetal fibronectin in cervicovaginal secretions of patients presenting with uterine contractions could rule out preterm labor within 7 and 14 days with a predictive value of 99 and 95.2%, respectively. In negative fetal fibronectin patients, preterm delivery before 32 and 37 weeks' is unlikely to occur with a predictive value of 97 and 85%, respectively. CONCLUSION: Cervicovaginal fetal fibronectin detected by a rapid bedside swab-test in women with symptoms of preterm labor compares favourably with quantitative assays and could prove useful in the management of preterm labor. This should be confirmed in a longer prospective study.

Adrenergic beta-Agonists↗

PubMed1997

The role of transvaginal sonography in predicting recurrent preterm labour in patients with intact membranes.

Our purpose was to determine whether funnelling of the cervical internal os, length of the endocervical canal, cervical index, funnel length and funnel width determined by transvaginal sonography are predictive of recurrent preterm labour. Of 112 women, 65 admitted to the hospital for preterm labour with intact membranes had transvaginal sonographic evaluation of the cervix before digital cervical examination and institution of tocolysis. The following measurements were obtained: (1) presence of funnelling, (2) endocervical canal length, (3) cervical index, (4) funnel length and (5) funnel width. Logistic regression analysis was performed to determine the variables that made a significant contribution to the prediction of recurrent preterm labour. A total of 65 eligible women completed the study. Recurrent preterm labour was significantly associated with the presence of funnelling (85.2% vs. 23.3%) and short endocervical canal length, large cervical index and long funnel length as noted on transvaginal cervical sonography. The presence of funnelling, shorter endocervical canal length, larger cervical index and longer funnel length were suggestive of true preterm labour and its recurrence. Transvaginal sonographic examination of the uterine cervix is a useful procedure to predict recurrent preterm labour with intact membranes.

Cervix Uteri↗

PubMed1999

Perinatal outcome and peripartum complications in preterm singleton and twins deliveries: a comparative study.

OBJECTIVE: Multiple pregnancy is one of the major risk factors for preterm births. The aim of the present study was to compare perinatal outcome and peripartum complications between twins and singletons, born preterm. STUDY DESIGN: The study population consisted of preterm deliveries of 435 pairs of twins (870 neonates) and the comparison group included 4754 preterm deliveries of singletons, born in the same period (January 1, 1989-December 31, 1996). Exclusion criteria were lack of prenatal care and births following infertility treatments. The three steps in statistical analysis consisted of (1) degree of concordance between the twins; (2) comparison between each twin (I and II) to their singleton comparison groups using SPSS computer program; (3) stratified analysis to examine perinatal mortality rates at different gestational age groups. RESULTS: The prevalence of preterm deliveries was 7.9% (6192/77610). Perinatal mortality was lower in twins of both birth orders, however, it was statistically significant only when APD is considered. Mortality rates in all gestational age groups and for both twin groups were lower than that of singleton [OR=0.45 (0.26-0.75; 95% CI) for twin-I; OR=0.36 (0.21-0.59; 95% CI) for twin-II]. Compared to singletons, twin gestations had less congenital malformations. Twin gestation had statistically lower rates of preterm premature rupture of membranes, severe pregnancy induced hypertension, oligohydramnios, placenta previa, placental abruption and clinical chorioamnionitis [12.2 vs.17.3%, 2.5 vs. 6.3%, 2.3 vs. 4.7%, 0.9 vs. 2.9%, 1.8 vs. 5%, 1.8 vs. 5.2%, respectively (P<0.01)]. Mothers of twins had less diabetes mellitus class B-R, hydramnios and chronic hypertension than that of singleton (1.8 vs. 2.6%, 5.5 vs. 7.4%, 3.7 vs. 4.8%, respectively). Cesarean section rates were significantly higher in twin's gestation. Mothers of twins tended to be older and of higher birth and gravidity order. CONCLUSIONS: Perinatal mortality rates and peripartum complications were lower in twin compared to singleton gestations.

Adult↗

PubMed2000

Congenital anomalies are an independent risk factor for neonatal morbidity and perinatal mortality in preterm birth.

OBJECTIVE: To determine whether congenital anomalies are associated with a high rate of neonatal morbidity in preterm birth. STUDY DESIGN: 312 singletons (22-36 wk) with congenital anomalies that were delivered preterm were compared with a random sample of 936 preterm singleton without congenital anomalies. Data was obtained using the computerized birth discharge records. Statistical analysis included univariate and multivariate logistic regression analyses. RESULTS: Three thousand five hundred and seventy-eight (3578) women with preterm births met the inclusion criteria (singleton with prenatal care). The prevalence of congenital anomalies in the study population was 8.7% (312/3578). Gestational age at delivery was significantly lower in the congenital anomaly group compared with the control (32.0+/-3.7 SD vs. 34.4+/-2.7 SD; p<0.001). The following pregnancy complications were higher in the group with congenital anomalies than in those without anomalies: severe pregnancy induced hypertension (PIH), hydramnions, oligohydramnion, intrauterine growth restriction (IUGR), fetal distress, cesarean section, malpresentation and mal position, abruption placenta, meconium stained amniotic fluid, 1 min Apgar score (<2), 5 min Apgar score (<7). Perinatal mortality rates in 28-32 wk and 33-36 wk were significantly higher in the group with congenital anomalies than in the control group. Neonatal morbidity data (necrotizing enterocolitis, respiratory distress syndrome, bronchopulmonary dysplasia, intraventricular hemorrhage, and sepsis) was available for 909 neonates (239 with congenital anomalies and 670 without congenital anomalies). After adjusting for gestational age, the presence of congenital anomalies remained strongly associated with neonatal morbidity (having one or more of the above mentioned conditions) (adjusted OR: 5.3, 95% CI 3.4-9.2). When adjusting for other confounding variables, congenital anomalies were strongly associated with neonatal morbidity (OR: 6.44, 95% CI 3.94-10.51), and perinatal mortality (OR: 3.08, 95% CI 2.04-4.65). In terms of attributable fraction in our population of preterm births, the proportion of neonatal morbidity and the proportion of perinatal mortality attributable to congenital malformation is 32% and 15%, respectively. CONCLUSION: Congenital anomalies in preterm birth are associated with a higher rate of pregnancy complications and are an independent risk factor for neonatal morbidity and perinatal mortality.

Adolescent↗

PubMed1999

Umbilical cord blood from preterm human fetuses is rich in committed and primitive hematopoietic progenitors with high proliferative and self-renewal capacity.

Human umbilical cord blood (CB) has been recognized as a source of hematopoietic stem cells for transplantation. While hematopoietic properties of neonatal CB from full-term pregnancies have been well characterized, little is known about CB from early gestational ages. We analyzed the content and the growth properties of primitive and committed hematopoietic progenitors in preterm CB from second trimester (week 16-28; n = 17) and early third trimester (week 29-34; n = 17) in comparison with term CB (n = 18). The frequency of CD34+ and CD34+CD38- cells was significantly higher in preterm than in term CB (mean, 2.51% and 0.56% vs 0.88% and 0.13%;p < 0.002). The number of colony forming units (CFU) in preterm CB was about twofold higher (230 +/- 6 vs 133 +/- 14/ 10(5) mononuclear cells; p < 0.05) and correlated with the content of CD34+ progenitors (r = 0.73). Long-term culture initiating cells (LTC-IC) were enriched about 2.5-fold (6.7 +/- 2.9 vs 2.6 +/- 1.2/10(5) cells; p < 0.05). Progenitors from preterm CB could be expanded in stroma-free liquid cultures supplemented with hematopoietic growth factors as efficiently as progenitors from term neonates. In short-term cultures containing erythropoietin (Epo), interleukin (IL)-1, IL-3, and IL-6, or granulocyte- (G-) and granulocyte-macrophage colony-stimulating factor (GM-CSF) together with stem cell factor (SCF) or Flt3 ligand (FL), expansion of CFUs was six- to eightfold at week 1. In long-term cultures containing thrombopoietin (TPO) and FL, an approximately 1000-fold expansion of multilineage progenitors was observed at week 10. In summary, we show that preterm CB compared with term CB is richer in hematopoietic progenitors, and that precursors from preterm CB can be extensively expanded ex vivo. This may have implications for the development of transplantation and gene transfer strategies targeting circulating fetal stem cells.

Antigens, CD34↗

PubMed2005

[Prevention of recurrent preterm birth: a comeback for progesterone?].

Progesterone has been prescribed for many years in women with preterm labor despite the lack of benefit for the fetus or neonate. The description of increased risk of intrahepatic cholestasis of pregnancy led to discontinuation of this prescription. Recently, several double-blind randomized trials have focused on the usefulness of progesterone for the prevention of recurrent preterm birth. In this review, we re-examine the pathophysiological rationale for the use of progesterone and discuss the biases and limitations of older studies, detailing two recent randomized trials which suggest use of progesterone should be revisited. Data from these trials appear to provide convincing evidence that preventive use of 17 alpha-hydroxyprogesterone administered by injections early in the course of pregnancy is effective only for women with a history of preterm delivery. This prescription could be part of a more global preventive strategy together with cervical cerclage and preventive treatment of bacterial vaginitis. During treatment, it is advisable to search for secondary hepatic effects. Conversely, there are still no data favoring the use of progesterone for preterm labor. Most preterm deliveries occurring in women without a history of preterm birth preventive use of progesterone should remain a rare indication.

17-alpha-Hydroxyprogesterone↗

PubMed2002

Skin conductance and behaviour during sensory stimulation of preterm and term infants.

AIM: To investigate the responses to painful and tactile stimulation in preterm and term infants in terms of changes in the plantar skin conductance activity (SCA) and behavioural state. Plantar SCA reflects activity in the sympathetic nervous system. DESIGN: The plantar SCA and behavioural state in response to nociceptive (the heel prick for blood samples, or immunization) and tactile (routine nursery handling) simulation was recorded in four different groups of infants (n=71): Preterm and term neonatal infants (defined here as up to 1 week old), and preterm and term infants in the postneonatal period. RESULTS: The preterm infants had significant increases in all skin conductance variables during both tactile and nociceptive stimulation (p<0.02), except for wave amplitude when newborns were heel pricked. The term infants displayed a more varied picture, but both the number and amplitude of the waves increased significantly during both procedures in the newborn groups, while the postneonatal groups only showed significant increases in wave amplitude during nociceptive stimulation (p<0.05). Tactile stimulation of the preterm newborn infants produced significantly higher increases in SCA than nociceptive stimulation (p<0.01), while the behavioural state was highest during nociceptive stimulation (p<0.05). A gradual change in this relation was seen with advancing total age. CONCLUSION: Non-painful sensory stimulation of infants, especially the newborn and preterm ones, can produce equal or higher levels of physiological stress activation than painful stimulation. Repeated nociceptive stimulation probably sensitises the infants to pain.

Female↗

PubMed1997

Immature adrenal steroidogenesis in preterm infants.

Screening for congenital adrenal hyperplasia is associated with a high rate of false positive results in preterm infants. Some RIA studies have detected elevated levels of 17 alpha-hydroxy-progesterone in severely ill preterm infants. However, because the antisera used with RIAs have a high degree of cross-reactivity, RIA results may not be reliable. Adrenal steroidogenesis was evaluated in 33 preterm infants born at less than 32 weeks' gestation using reversed-phase high performance liquid chromatography. 17 alpha-hydroxyprogesterone, 11-deoxycortisol, and/or corticosterone were detectable temporarily at about 29 weeks of equivalent gestational age in 27 of 33 preterm infants. Levels of cortisol and cortisone were markedly decreased in 4 of 16 infants whose mothers had received steroids. These findings suggest that the activities of 21-hydroxylase, 11 beta-hydroxylase, and 18-hydroxylase are decreased at about 29 weeks of equivalent gestational age. Steroid levels should be carefully monitored in preterm infants with elevated intermediate steroids and preterm infants whose mothers receive steroids before delivery using reversed-phase high performance liquid chromatography.

17-alpha-Hydroxyprogesterone↗

PubMed2001

Plasma selenium in preterm and term infants during the first 12 months of life.

The goal of the present study was to prospectively assess the plasma selenium (Se) concentrations of term and preterm infants during the first year of life in relation to gestational age and nutrition. Blood specimens were collected from orally formula-fed preterm infants (gestational age < 32 weeks, birth weight < 1500 g): 1.) in hospital and 2.) corrected for gestational age parallel to healthy term breast and formula-fed infants at the ages of 1, 4 and 12 months. All infants were fed according to a standardized nutritional concept, solids and follow-up formula were introduced at the age of 4 months. Plasma selenium in preterm infants in hospital was 11.7 (6.5-20.8) microg/l and 11.6 (8.8-16.7) microg/l at 4 weeks corrected for gestational age. At the age of 4 months plasma selenium was still significantly lower than in the other groups: Preterm infants: 17.1 (10.4-30.5) microg/l; formula-fed term infants: 31.3 (24.3-47.5) microg/l; breast-fed term infants: 45.6 (27.1-65.1) microg/l). The levels of breast-fed infants were significantly higher than those of both formula-fed groups up until the introduction of solids. Preterm infants had significantly low plasma selenium levels up until a postnatal age of at least 6 months. The levels were lower than those of term infants fed an identical unsupplemented infant formula during the first 4 months of life. These data support routine monitoring in hospital and selenium supplementation of preterm infants, preferably in hospital before discharge.

Gestational Age↗

PubMed1993

Long-term outcome of infants born preterm.

This chapter outlines some of the many long-term health problems to be expected in surviving preterm children. They have higher rates of sensorineural impairments (such as cerebral palsy, and visual, auditory and intellectual impairments) and sensorineural disabilities from these impairments, than children born at term. In addition, they grow poorly and have higher rates of other health problems, including poorer respiratory health in early childhood. There is little doubt that preterm children contribute disproportionately to the prevalence of health problems in childhood. However, there are still many gaps in our knowledge of the outcome for preterm survivors, particularly regarding outcome in adulthood. Obstetricians and neonatologists working in intensive care, as well as parents, want to know the long-term outcome for preterm children born today, not that of children born a generation ago when fewer preterm children (particularly those of extremely low birthweight) survived. Despite the many problems, the conclusion is that most preterm children are as healthy as term children, suffering only usual childhood illnesses; we feel confident that the majority make, and will continue to make, useful contributions to their families and the societies in which they live.

Cohort Studies↗

PubMed1996

Prostaglandins in selected reproductive tissues in preterm and full-term gestations.

We investigated differences in maternal plasma and trophoblast prostaglandin metabolism associated with preterm births. Tissue prostaglandins (PGs) E2 and F2 alpha and the stable plasma PGF2 alpha metabolite, 13,14-dihydro-15-keto-PGF2 alpha, were measured in preterm (< 37 weeks) and term (< or = 37 weeks) births. Amnion PGE2 in preterm (106.1 +/- 15.7 ng/g wet weight tissue; x +/- SEM; n = 37) was lower than in term (176.6 +/- 22.7 ng/g wet weight; x +/- SEM; n = 34, P < 0.02). Placenta PGE2 was lower in preterm (34.7 +/- 19.7 ng/g wet weight; x +/- SEM) than in term (103.3 +/- 28.0 ng/g wet weight; x +/- SEM, P < 0.04). Preterm PGF2 alpha was consistently lower in the amnion (106.8 +/- 17.5 ng/g wet weight) and placenta (102.5 +/- 8.7 ng/g wet weight) than in term amnion (188.2 +/- 24.8 ng/g wet weight; P < 0.01) and placenta (128.9 +/- 7.8 ng/g wet weight; P < 0.03). Chorionic PGE2 and plasma PGF2 alpha metabolite followed this trend but did not reach significance. These findings suggest qualitative and quantitative differences in maternal and trophoblast eicosanoid metabolism between term and preterm parturition.

Adult↗

PubMed2002

Neighborhood socioeconomic status, maternal race and preterm delivery: a case-control study.

PURPOSE: To explore associations between neighborhood socioeconomic context and preterm delivery, independent of maternal and family socioeconomic status, in African-American and white women. METHODS: A case-control study of African-American (n = 417) and white (n = 1244) women delivering infants at the University of California, San Francisco's Moffitt Hospital, between 1980 and 1990. RESULTS: Neighborhood socioeconomic contexts were associated with preterm delivery but associations were non-linear and varied with race/ethnicity. For African-American women, living in a neighborhood with either high or low median household income was associated with an increased risk of spontaneous preterm delivery, as was living in a neighborhood with large increases or decreases in the proportion of African-American residents during the study decade. Residence in neighborhoods with high and low rates of male unemployment was associated with a decreased risk of preterm delivery. Among white women only large positive and negative changes in neighborhood male unemployment were associated with risk of preterm delivery. CONCLUSIONS: Neighborhood factors and changes in neighborhoods over time are related to preterm delivery, although the mechanisms linking local environments to maternal risk remain to be specified.

Adult↗

PubMed2003

Association of Lewis blood group phenotype with preterm premature rupture of membranes.

OBJECTIVE: To evaluate the distribution of Lewis blood group phenotype and secretor status among women with preterm premature rupture of membranes. METHODS: ABO and Lewis blood group phenotypes were determined in 20 consecutive women with preterm premature rupture of membranes. The control group was composed of 48 women from our database without known history of preterm delivery. RESULTS: Of the 20 patients with preterm premature rupture of membranes six had blood type A (30%), nine type B (45%), two type AB (10%), three type O (15%), three Le(a(-)b(+)) (15%), one Le(a(+)b(-)) (5%), and 17 had Le(a(-)b(-)) (80%). Of the 48 controls, 18 had blood type A (37.5%), 10 type B (20.9%), two type AB (4.1%), 18 type O (37.5%), 37 Le(a(-)b(+)) (77.1%), six Le(a(+)b(-)) (12.5%), and five had Le(a(-)b(-)) (10.4%). The difference in the proportions of the A, B, AB, and O phenotypes between the groups was not statistically significant. The distribution of ABO and Lewis phenotype in the control group was similar to that in the general population. The proportion of combined recessive and nonsecretor phenotypes Le(a(+/-)b(-)) between patients with preterm premature rupture of membranes (17 of 20, 85%) and controls (11 of 48, 22.9%) was statistically significant (P <.001). CONCLUSIONS: Women with the Le(a(-)b(+)) phenotype who do secrete Le(b) antigen may have a protective effect against preterm premature rupture of membranes.

ABO Blood-Group System↗