Bo Jacobsson

Role of cytokines in preterm labour and brain injury

Intrauterine infection induces an intra‐amniotic inflammatory response involving the activation of a number of cytokines and chemokines which, in turn, may trigger preterm contractions, cervical ripening and rupture of the membranes. Infection and cytokine‐mediated inflammation appear to play a prominent role in preterm birth at early gestations (<30 weeks). The role of infection/inflammation in preterm birth in Europe has been incompletely characterised. The rate of preterm birth in Sweden is lower, and the rate of chorioamnionitis, bacterial vaginosis (BV), neonatal sepsis, and urinary tract infections during pregnancy is lower compared with the USA. In a Swedish population of women with preterm labour or preterm premature rupture of the membranes (PPROM) <34 weeks of gestation, microorganisms were detected in the amniotic fluid in 25% of women with PPROM and in 16% of those in preterm labour. Nearly half of these women had intra‐amniotic inflammation defined as elevated interleukin‐6 (IL‐6) and IL‐8, and there was a high degree of correlation between cytokine levels and preterm birth or the presence of microbial colonisation. These data do not support the hypothesis that infection‐related preterm birth is less frequent in northern Europe than elsewhere. The intra‐amniotic inflammatory response has also been associated with white matter injury and cerebral palsy. We find that in experimental models, induction of a systemic inflammatory response using lipopolysaccharide activates toll‐like receptors (TLRs), which produce either white matter lesions or increase brain susceptibility to secondary insults. Recently, IL‐18 in umbilical blood was shown to correlate with brain injury in preterm infants and IL‐18 deficiency in mice decreases CNS vulnerability.

Cerebral palsy and restricted growth status at birth: population-based case-control study

Objectiveu2002 To evaluate the association between growth status at birth and subsequent development of cerebral palsy in preterm and term infants.

Effects of blood sample handling procedures on measurable inflammatory markers in plasma, serum and dried blood spot samples

The interests in monitoring inflammation by immunoassay determination of blood inflammatory markers call for information on the stability of these markers in relation to the handling of blood samples. The increasing use of stored biobank samples for such ventures that may have been collected and stored for other purposes, justifies the study hereof. Blood samples were stored for 0, 4, 24, and 48 h at 4 degrees C, room temperature (RT), and at 35 degrees C, respectively, before they were separated into serum or plasma and frozen. Dried blood spot samples (DBSS) were stored for 0, 1, 2, 3, 7, and 30 days at the same temperatures. 27 inflammatory markers in serum and plasma and 25 markers in DBSS were measured by a previously validated multiplex sandwich immunoassay using Luminex xMAP technology. The measurable concentrations of several cytokines in serum and plasma were significantly increased when blood samples were stored for a period of time before the centrifugation, for certain cytokines more than 1000 fold compared to serum and plasma isolated and frozen immediately after venepuncture. The concentrations in serum generally increased more than in plasma. The measurable concentrations of inflammatory markers also changed in DBSS stored under various conditions compared to controls frozen immediately after preparation, but to a much lesser degree than in plasma or serum. The study demonstrates that trustworthy measurement of several inflammatory markers relies on handling of whole blood samples at low temperatures and rapid isolation of plasma and serum. Effects of different handling procedures for all markers studied are given. DBSS proved to be a robust and convenient way to handle samples for immunoassay analysis of inflammatory markers in whole blood.

Quantification of Ureaplasma urealyticum DNA in the amniotic fluid from patients in PTL and pPROM and its relation to inflammatory cytokine levels.

Objective. To study the effect of the amniotic fluid quantity of Ureaplasma urealyticum DNA on inflammatory response levels in women with preterm labor (PTL) and preterm prelabor rupture of membranes (pPROM). Design. A prospective multi‐center follow up study. Setting. Sahlgrenska University Hospital, Göteborg, Sweden and Turku University Hospital, Turku, Finland. Sample. Eleven U. urealyticum positive samples obtained after transabdominal amniocenteses in 197 women presenting with PTL and pPROM. Methods. The U. urealyticum positive samples were analyzed with real‐time polymerase chain reaction, using the Lightcycler instrument with primers specific for U. urealyticum 16 S rDNA. The amniotic fluid samples were analyzed for tumor necrosis factor (TNF)‐α, interleukin (IL)‐6, IL‐1β and IL‐10 with enzyme‐linked immunosorbent assays. Main outcome measures. Correlation between U. urealyticum DNA concentrations in the amniotic fluid and inflammatory cytokine levels. Results. The concentrations of U. urealyticum DNA varied between 0.024 and 934 μg/mL. A significant correlation between U. urealyticum DNA and TNF‐α level was observed. No correlation with the other cytokines was found. Women with PTLhad higher levels of U. urealyticum DNA and a different cytokine pattern than women with pPROM. Conclusions. U. urealyticum in the amniotic fluid induces an inflammatory reaction in a dose dependent manner and the quantity of U. urealyticum DNA is well correlated with the level of the inflammatory cytokine TNF‐α.

Asphyxia‐related risk factors and their timing in spastic cerebral palsy

Objectiveu2002 To investigate the association of asphyxia‐related conditions (reducing blood flow or blood oxygen levels in the fetus) with spastic cerebral palsy (CP) considering different gestational age groups and the timing of risk.

Reference population for international comparisons and time trend surveillance of preterm delivery proportions in three countries

BackgroundInternational comparison and time trend surveillance of preterm delivery rates is complex. New techniques that could facilitate interpretation of such rates are needed.MethodsWe studied all live births and stillbirths (≥ 28 weeks gestation) registered in the medical birth registers in Sweden, Denmark and Norway from 1995 through 2004. Gestational age was determined by best estimate. A reference population of pregnant women was designed using the following criteria: 1) maternal age 20–35, 2) primiparity, 3) spontaneously conceived pregnancy, 4) singleton pregnancy and 5) mother born in the respective country. National preterm delivery rate, preterm delivery rate in the reference population and rate of spontaneous preterm delivery in the reference population were calculated for each country.ResultsThe total national preterm delivery rate (< 37 completed gestational weeks), increased in both Denmark (5.3% to 6.1%, p < 0.001) and Norway (6.0% to 6.4%, p = 0.006), but remained unchanged in Sweden, during 1995–2004. In Denmark, the preterm delivery rate in the reference population (5.3% to 6.3%, p < 0.001) and the spontaneous preterm delivery rate in the reference population (4.4% to 6.8%, p < 0.001) increased significantly. No similar increase was evident in Norway. In Sweden, rates in the reference population remained stable.ConclusionReference populations can facilitate overview and thereby explanations for changing preterm delivery rates. The model also permits comparisons over time. This model may in its simplicity prove to be a valuable supplement to assessments of national preterm delivery rates for public health surveillance.

Cervical length in women in preterm labor with intact membranes: relationship to intra-amniotic inflammation/microbial invasion, cervical inflammation and preterm delivery

Intra‐amniotic infection, diagnosed by microbial invasion of the amniotic cavity (MIAC) and/or the presence of intra‐amniotic inflammation (IAI), is related to adverse perinatal outcome in women with preterm labor. Due to the subclinical nature of IAI, a correct diagnosis depends on amniocentesis, which is an invasive method not performed as a clinical routine. The aim of this study was to evaluate if cervical length measured by transvaginal sonography could assist in the identification of women at high risk for IAI.

The joint effect of vaginal Ureaplasma urealyticum and bacterial vaginosis on adverse pregnancy outcomes

Objective. To examine associations of vaginal Ureaplasma urealyticum (UU) and bacterial vaginosis (BV) with preterm delivery (PTD), small for gestational age (SGA), and low birth weight (LBW). Material and methods. A population‐based, prospective cohort study of 2,927 pregnancies. After exclusion of multiples and antibiotic use sample size was 2,662. BV (Amsels criteria) and UU (culture) were assessed in week 17. Gestational age was determined by last menstrual period, confirmed by ultrasound measurement in 97.5%. SGA infants were calculated from intrauterine fetal growth measurements. Results. There was no increased risk for spontaneous PTD among women with BV only (crude odds ratio 1.0, 95% CI 0.4–2.7), among women with UU only (1.3, 0.8–2.0), nor among women with UU + BV (0.9, 0.4–2.3) compared to women without UU and BV. However, there was a threefold increased risk of a LBW birth in women with UU + BV (3.1, 1.8–5.4), a twofold risk of a LBW birth among women with UU only (1.9, 1.3–2.9), but no increased risk among women with BV only (0.8, 0.3–2.2). Similarly, women with UU + BV had over a twofold increased risk of an SGA birth (2.3, 1.3–4.0), women with UU only had a 70% increase (1.7, 1.1–2.5), whereas a nonsignificant increase was found in women with BV only (1.3, 0.6–2.9). Adjustment by established confounders (smoking, previous PTD, previous LBW, and Escherichia coli) did not affect risk estimates. Conclusion. This analysis suggests that UU is independently associated with fetal growth and LBW and that BV with UU may enhance the risk of these outcomes.

Bacterial vaginosis in early pregnancy is associated with low birth weight and small for gestational age, but not with spontaneous preterm birth: A population-based study on Danish women

Objective. To analyze the association between bacterial vaginosis (BV) in early pregnancy and preterm birth, low birth weight (LBW) and small for gestational age (SGA) in a Danish population. Methods. A geographically defined population-based prospective study of Danish-speaking pregnant women over18 years of age enrolled before week 24 and followed until delivery. BV was diagnosed by Amsels clinical criteria at enrolment. Results. At enrolment, 13.7% had BV. BV was not associated with an increased risk of spontaneous preterm birth (crude OR 0.8 (0.5–1.5)). Nulliparity was found to affect birth weight to such a degree that this variable was used for stratification. In nulliparous women BV was associated with LBW (adj. OR 4.3 (1.5–12)) and SGA (adj. OR 1.6 (0.7–3.1)) compared to nulliparous without BV. No such associations were seen for multiparous women with BV. Conclusions. BV was not associated with spontaneous preterm birth, but was associated with both LBW and SGA in nulliparous women.

Risk factors for bacterial vaginosis in pregnancy: a population-based study on Danish women

Background. No larger population‐based study of bacterial vaginosis in pregnancy has previously been available. The objective of this study was to examine risk factors for bacterial vaginosis in pregnancy. Design. From a prospective population‐based cohort of 3,596 eligible pregnant women, 2,927 (81.4%) completed the study. Methods. Women were asked to participate in this study at their first prenatal visit at 17 gestational weeks (range 7 + 3–24 + 0). Samples from the genital tract were taken at enrolment. Bacterial vaginosis was determined by Amsels clinical criteria (3 out of 4: pH > 4.5, homogenous discharge, clue cells, and positive amine test). Data were collected from three questionnaires completed during the second and third trimesters and correlated with the diagnosis of bacterial vaginosis. Crude and adjusted relative risks (reproductive, medical, behavioral, sexual, and sociodemographic factors) were computed. Results. At enrolment, bacterial vaginosis was diagnosed in 13.7% of Danish pregnant women. Significant risk factors for bacterial vaginosis were: daily coitus (adjusted relative risk 2.09 [1.43–3.04]), being single (1.76 [1.21–2.56]), smoking more than 10 cigarettes daily at conception (1.59 [1.29–1.93]), previous genital infection with Chlamydia trachomatis or Neisseria gonorrhoeae (1.39 [1.07–1.79]), and consuming 2 or more drinks per week (1.33 [1.02–1.74]) after control for confounding factors. Conclusion. In pregnancy, women who have daily coitus, are single, smokers, with a previous sexually transmitted disease, or with high alcohol consumption in pregnancy are at increased risk for bacterial vaginosis. Information on these risk factors may be important when planning preventive and treatment strategies of bacterial vaginosis in pregnancy.