Biomedical subjects

Svein Rasmussen

Publications and source records attributed to Svein Rasmussen.

16 recordsLinked to original sources

PubMed2006

Trends in fetal and infant survival following preeclampsia.

CONTEXT: Management of preeclampsia often culminates in induced delivery of a very preterm infant. While early termination protects the fetus from an intrauterine death, the newborn then faces increased risks associated with preterm delivery. This practice has increased in recent decades, but its net effect on fetal and infant survival has not been assessed. OBJECTIVE: To assess the effect on fetal and infant survival of increased rates of early delivery of preeclamptic pregnancies. DESIGN, SETTING, AND PARTICIPANTS: Population-based observational longitudinal study using registry data from 804 448 singleton first-born infants with Norwegian-born mothers and registered in the Medical Birth Registry of Norway between 1967 and 2003. MAIN OUTCOME MEASURES: Odds ratio (OR) of fetal and early childhood death in relation to preeclampsia. RESULTS: Among preeclamptic pregnancies, inductions before 37 weeks increased from 8% in 1967-1978 to nearly 20% in 1991-2003. During this period, the adjusted OR for stillbirth decreased from 4.2 (95% confidence interval [CI], 3.8-4.7) to 1.3 (95% CI, 1.1-1.7) for preeclamptic compared with nonpreeclamptic pregnancies. During the same period, the OR for neonatal death after preeclamptic pregnancy remained relatively stable (1.7 in 1967-1978 vs 2.0 in 1991-2003). Later infant and childhood mortality also showed little change. CONCLUSIONS: Fetal survival in preeclamptic pregnancies has vastly improved over the past 35 years in Norway, presumably because of more aggressive clinical management. However, the relative risk of neonatal death following a preeclamptic pregnancy has not changed over time.

Cesarean Section↗

PubMed2006

The effects of smoking and hypertensive disorders on fetal growth.

BACKGROUND: It is well known that smoking and pregnancy induced hypertension (PIH) are associated with decreased fetal growth. It has been reported that in preeclampsia the fetal growth deficit attributable to smoking is higher, which has been contradicted in other studies. We therefore evaluated the effects on fetal growth of early- and late onset PIH and chronic hypertension and how cigarette smoking modify these effects. We also quantified the proportion of small for gestational age (SGA) cases attributable to PIH, chronic hypertension, and smoking. METHODS: Population-based study based on record of 215598 singleton pregnancies from the Medical Birth Registry of Norway. RESULTS: In severe preeclampsia, mild preeclampsia, transient hypertension, and normotension in term birth, odds ratios (ORs) of SGA in smokers compared with non-smokers were 1.4 (95% confidence interval 0.9, 2.2), 1.6 (1.3, 1.9), 2.3 (1.8, 3.1), and 2.0 (1.9, 2.1), respectively. For preterm births, corresponding ORs were 1.3 (0.9, 2.0), 1.8 (1.1, 3.0), 4.1 (1.9, 9.0), and 1.7 (1.4, 2.0), respectively. The effect of early onset PIH was stronger than that in term births, while the effect of smoking was equal in preterm and term newborns. Only in non-smokers who delivered at term, the rates of SGA significantly increased with the severity of PIH (ORs = 1.3 (1.1, 1.5), 1.8 (1.7, 2.0), and 2.5 (2.2, 3.0) for transient hypertension, mild-, and severe preeclampsia, respectively). The combined effects of smoking and hypertension were generally not synergistic. The effect of smoking was not stronger in women who had chronic hypertension. Nor were the effects of chronic hypertension stronger in smokers. PIH explained 21.9 and 2.5% of preterm and term cases of SGA, respectively, while smoking explained 12% of SGA cases. CONCLUSION: The effects of hypertensive disorder and smoking were generally not synergistic, which suggest that they may exert their main actions on separate sites or work through separate mechanisms within or outside the placenta. If smoking were eliminated in pregnant women, the number of SGA cases would be reduced by 12%.

Journal Article↗

PubMed2006

Foetal size and body proportion at 17-19 weeks of gestation and neonatal size, proportion, and outcome.

OBJECTIVE: To determine whether proportionate or disproportionate foetal smallness at 17 to 19 weeks of gestation in low-risk pregnancies was associated with size, body constitution, and adverse outcome at birth. METHODS: We included ultrasound measurements at 17-19 weeks of gestation in 7285 uncomplicated pregnancies with reliable information on last menstrual period. We considered a foetus with both mean abdominal diameter (MAD) and biparietal diameter (BPD) below the 10th percentile for gestational age, gender, and parity as symmetrically small. Those who had MAD below the 10th percentile and BPD at or above the 10th percentile were asymmetrically small (thin and small). RESULTS: The occurrence of small for gestational age (SGA) (birth weight below the 10th percentile) decreased with increasing second trimester MAD percentile (P<0.0001). The risk in foetuses which were both thin and extremely small (MAD below the 2.5th percentile) of having weight, ponderal index, crown-heel length, or head circumference below the 10th percentile at birth was 19-28%. The risk of perinatal composite outcome (prenatal death, Apgar score after 5 min < or =7, birth weight below the 10th percentile, or <1500 g, or preterm birth) was 37%. Apgar score of < or =7 at 5 min and explained foetal death both occurred in 7%, which was significantly higher than those with larger MAD. CONCLUSION: Asymmetric as well as symmetric foetal smallness may start early in pregnancy. Symmetric and particularly asymmetric small foetuses at 17-19 weeks of gestation were generally lighter, shorter, and thinner at birth and had more often adverse perinatal outcome.

Abdomen↗

PubMed2006

Longitudinal reference ranges for estimated fetal weight.

OBJECTIVE: The aims of the present study were to establish reference ranges for the growth of estimated fetal weight (EFW) between gestational weeks 20 and 42 and to determine the effect of fetal and maternal factors. METHODS: This prospective longitudinal study was based on 634 low-risk pregnancies and a total of 1799 examinations. Gestational age was computed from last menstrual period. Head circumference, abdominal circumference, and femur length were measured using ultrasound, and EFW was calculated using the formula of Combs et al. The statistical analysis was based on regression analysis and multilevel modeling. RESULTS: Intrauterine growth expressed by EFW showed a continuous pattern until term. Males were calculated to be 5% heavier than female fetuses at 20 gestational weeks and 3% at 40 weeks. Otherwise, the fetal and maternal effects on intrauterine growth correspond to a weight shift of 1.3% for breech/nonbreech, 2.5% for each increase in maternal height tertile, and -4% for smoking/nonsmoking. Maternal age higher than 34 years had a significant increased EFW of 4.5% compared with maternal age less than 24 years. Cephalic index in the third tertile had a 1.1% lower EFW compared with the first tertile. Maternal weight, body mass index, and parity did not influence the EFW. Terms for customization to individualize the growth patterns are presented. CONCLUSIONS: The present growth chart is recommended as robust reference ranges for assessing EFW and growth. Fetal and maternal variables can be added into the models to individualize the prediction of EFW.

Adult↗

PubMed2006

Group intervention for women with pelvic girdle pain in pregnancy. A randomized controlled trial.

BACKGROUND: Low back and pelvic pain is common in pregnancy and postpartum, but there is no well documented effect of treatment in pregnancy. The aim of the study was to assess whether a group intervention program for pregnant women with pelvic girdle pain has any effect on pain and daily function postpartum. METHODS: Pregnant women with pelvic pain between the 18th and 32nd week of gestation were invited to participate in a randomized clinical study. Among 958 examined women, 569 (59%) fulfilled the inclusion criteria. Women randomized to the intervention group (n=275) participated in an education program that consisted of information, ergonomics, exercises, pain management, advice for daily life movement, pelvic belt/crutches, and information about delivery. Women randomized to the control group (n=285) were not offered any treatment, but were free to seek advice or other treatment. Clinical measures and self-evaluated utility of the intervention were measured by a visual analogue scale 0-10. RESULTS: Mean debut of pelvic girdle pain in pregnancy was at week 15. Altogether 42% of the women reported problems with low back pain earlier, and 34% reported a family history of pelvic girdle pain in pregnancy. Median visual analogue scale score for all activities at inclusion was 6 both in the control group and the intervention group. At 6 and 12 months postpartum the score was reduced to 1.7/1.6 and 1.1/0.9. In the intervention group, 75% marked a self-evaluated utility visual analogue scale score >7. In the control group, 60% had searched for alternative treatment. CONCLUSIONS: Postpartum pelvic girdle pain improved with time both in the intervention group and the control group, but there were no statistically significant differences between the groups. Self-evaluated utility of the intervention was, however, high in the intervention group.

Activities of Daily Living↗

PubMed2006

Secular trends in socio-economic status and the implications for preterm birth.

The rate of preterm birth in the developed world has been shown to be increasing, in part attributable to obstetric intervention. It has been suggested that this may be a differential increase between socio-economic groups. We aimed to assess whether the preterm rate in Norway is different in socio-economic groups defined by maternal education, and to determine the extent to which a difference is attributable to a socio-economic differential in obstetrical intervention, in terms of caesarean section or induction of labour. We used data from the Medical Birth Registry of Norway from 1980 to 1998 with preterm rate as the outcome and maternal educational level, marital status and obstetric intervention as exposure variables. In multivariable analyses, adjustment was made for maternal age, year of birth and birth order, and secular trends were assessed according to year of birth. The preterm birth rate was highest in the lowest socio-economic group. An increase of 25.2% in the preterm rate was seen over the observation period. No apparent differential was seen in the increase of the crude preterm rates between socio-economic groups, although in multivariable analyses there was a significant interaction between socio-economic group and time, implying a stronger effect of low education towards the end of the observation period attributable to demographic change. In conclusion, the preterm birth rate increased over time, but was mainly due to an increase in obstetric interventions. No closing of the gap between socio-economic groups was observed.

Cesarean Section↗

PubMed2006

Accuracy of second trimester fetal head circumference and biparietal diameter for predicting the time of spontaneous birth.

AIMS: Previous studies suggested that head circumference (HC) predicts the date of confinement better than the biparietal diameter (BPD). The present study aimed to prospectively test this assumption. METHODS: A prospective study including 4179 consecutive women attending the second trimester routine ultrasound examination at 17-20 weeks of gestation. Outer-outer BPD and HC were determined as the average of three repeated measurements. Twins were excluded. Time of delivery was noted, the differences between this and the predicted date of delivery calculated with HC and BPD (based on a pregnancy duration of 282 days), and the two methods were compared using Wilcoxon signed rank test. RESULTS: For the entire group, the median differences between actual and predicted delivery with HC and BPD were 0.9 and 1.2 days, respectively. For deliveries with a spontaneous onset of labor (n=3336) the corresponding differences were 0.9 and 1.4 days. The difference between the HC and BPD methods was significant (P<0.0001). In the group of spontaneous onset of labor, there were 05.6% post-term pregnancies (>or=296 days) according to HC and 5.7% according to BPD. CONCLUSION: Provided that the expected pregnancy duration was 282 days, both HC and BPD predicted spontaneous birth with a mean accuracy of one day, HC being significantly better than BPD.

Anthropometry↗

PubMed2005

Longitudinal reference charts for growth of the fetal head, abdomen and femur.

OBJECTIVES: The aims of the present study were to establish improved reference charts for growth of the fetal head, abdomen and femur, and to determine the effect of fetal and maternal factors. STUDY DESIGN: This prospective longitudinal study included 650 low-risk pregnancies. Outer-outer biparietal diameter (BPD), head circumference (HC), mean abdominal diameter (MAD), abdominal circumference (AC) and femur length (FL) were measured by ultrasound, and the statistical analysis was based on regression analysis and multilevel modeling. RESULTS: Reference percentiles for the growth of MAD, AC and FL showed continuous growth in gestational week 10-40, while BPD and HC showed a slightly blunted growth toward the end of pregnancy. FL was the only variable that was not influenced by gender. There was a significant negative association between breech presentation and all five biometrical variables, while maternal weight was positively associated with all five variables. Cephalic index significantly influenced BPD and HC. Maternal height had a positive effect on BPD, HC, AC and FL, and parity had a positive effect on MAD and AC, while smoking influenced negatively HC, MAD, and FL. Terms for calculating conditional reference values and customisation for individualised growth assessment are presented. CONCLUSIONS: New reference charts for the growth of fetal head, abdomen and femur are suggested for assessing fetal size and growth, and can be adjusted for maternal and fetal factors to suite individual pregnancies.

Abdomen↗

PubMed2005

Haemoglobin and serum ferritin in pregnancy--correlation with smoking and body mass index.

BACKGROUND: Little is known about factors which may influence haemoglobin (Hb) and ferritin levels in pregnancy. AIM: To analyse if haemoglobin and ferritin levels during pregnancy are influenced by maternal age, body mass index, cigarette smoking, and iron supplementation. METHODS: A random sample of 561 parous pregnant women were recruited from the catchment areas of three Scandinavian university hospitals. The analyses were based on 5024 haemoglobin and 1529 ferritin measures sampled from the first trimester to 42 weeks of gestation. Multilevel modelling was used to construct mean and percentile curves for haemoglobin and ferritin by gestational age. RESULTS: Women aged 25-34 years had significantly higher haemoglobin values than older and younger women. Haemoglobin values were significantly lower for women with body mass index < 19 kg/m(2) than for women with body mass index > or =19. Smokers had significantly lower haemoglobin values throughout pregnancy compared to non-smokers, with the lowest values among women who smoked 1-9 cigarettes per day. There were no similar associations between ferritin and maternal age, body mass index, or smoking. Women with iron supplementation throughout pregnancy had a higher relative increase in haemoglobin concentration toward the end of pregnancy. In non-supplemented women the decline in ferritin concentration was significantly steeper than in those who received iron supplementation. CONCLUSIONS: Haemoglobin levels during pregnancy are significantly associated with maternal age, cigarette smoking, body mass index, and iron supplementation. No such associations were found with ferritin levels, except for iron supplementation.

Adult↗

PubMed2005

Fetal age assessment based on femur length at 10-25 weeks of gestation, and reference ranges for femur length to head circumference ratios.

BACKGROUND: The aim of the present study is to establish new reference charts for gestational age assessment based on fetal femur length (FL), and new reference ranges for FL to head ratios at gestational weeks 10-25, and to determine the effect of maternal and fetal factors on these charts. METHODS: Six hundred fifty low-risk women with regular menstrual periods and singleton pregnancies were recruited to a prospective cross-sectional study after obtaining written consent. FL, outer-outer biparietal diameter (BPD), and head circumference (HC) were measured at 10-25 weeks of gestation. We used regression analysis in order to construct mean curves and to assess the effect of maternal and fetal factors on age assessment. RESULTS: The new chart for age assessment by means of FL was based on 636 measurements. The 95% CI of the mean corresponded to <1 day. The variation between the mean and the 90th percentile was 5, 6, and 7 days at 13, 18, and 23 weeks, respectively, similar to the results when using BPD or HC. Maternal age modestly influenced gestational age assessment (1.3 days/10 years, P = 0.005), whereas smoking, height, body mass index, multiparity, fetal sex, cephalic index, and breech presentation had no impact. Reference charts for FL to head ratios have been presented. Maternal age, fetal sex, and cephalic index influenced the FL/BPD ratio, whereas only fetal sex influenced FL/HC. CONCLUSIONS: Fetal age assessment based on FL is an equally robust method as using HC. FL/HC is a more robust ratio to characterize fetal proportions than is FL/BPD.

Adolescent↗

PubMed2004

The effect of umbilical venous constriction on placental development, cord length and perinatal outcome.

BACKGROUND: Umbilical vein constriction at the fetal abdominal inlet is a common finding after week 13, when the period of umbilical herniation is brought to an end. AIMS: To test the hypothesis that a constricting umbilical ring within physiological ranges affects fetal hemodynamics by either pooling blood in the placenta or restricting nutrient transfer to the fetus and thus shift the birthweight/placental weight (BW/PW) ratio. A constriction could also cause pressure changes and elongation of the cord and possibly be a disadvantage during labour. STUDY DESIGN: Cross-sectional. SUBJECTS: 359 Low-risk singleton pregnancies at 13-40 weeks of gestation. OUTCOME MEASURES: Standard deviation score (z-score) and regression analysis were used to determine the effect of umbilical vein constriction (expressed by increased blood velocity) on birthweight/placental weight ratio (BW/PW), cord length, Apgar score and emergency delivery due to fetal distress. RESULTS: Umbilical venous constriction had a mild but significant effect on BW/PW in male (p=0.018) but not in female fetuses. Increased constriction was also associated with increased length of the cord but only in female fetuses (p=0.019). Cord length was positively related to birthweight and placental weight, but an increased length of the cord was also associated with decreasing BW/PW ratio for the male fetuses only (p=0.044). Increasing degree of venous constriction was associated with Apgar score < or =7 at 1 (p=0.009) but not at 5 min after birth and was not associated with emergency delivery. CONCLUSION: Physiological umbilical venous constriction exerts a mild but significant gender-specific hemodynamic impact on intrauterine development.

Adolescent↗

PubMed2004

Fetal age assessment based on ultrasound head biometry and the effect of maternal and fetal factors.

BACKGROUND: Maternal height and weight have increased during the past 20 years, as has birthweight. The aim of the present study was to establish new reference charts for gestational age (GA) assessment using fetal biparietal diameter (BPD) and head circumference (HC), and to determine the effect of maternal and fetal factors on age assessment. METHODS: This was a prospective, cross-sectional study of 650 healthy women with regular menstrual periods and singleton uncomplicated pregnancies, recruited after written consent. BPD (outer-outer) and HC were measured at 10-24 weeks of gestation. We used regression analysis to construct mean curves and assess the effect of maternal and fetal factors on age assessment. RESULTS: BPD and HC were successfully measured in 642 participants. Using BPD and HC before 20 weeks, the new charts gave 3-8 days higher GA assessment than the charts presently in use, and <1 day difference compared to other recently established charts. Maternal age, multiparity, fetal gender, breech position and shape of fetal head affect GA estimation by 1-2 days when using BPD (p = 0.0001-0.02). Only maternal age and fetal gender affected GA estimation when using HC (</= 1 day, p = 0.001). CONCLUSIONS: Our new charts for assessing gestational age based on fetal head biometry are notably different from charts presently in use. Maternal and especially fetal factors affect gestational age assessment when using BPD, but less so for the HC method, which is suggested as the more robust method.

Adolescent↗

PubMed2003

Fetal growth and body proportion in preeclampsia.

OBJECTIVE: To evaluate the effects of early- and late-onset preeclampsia on fetal growth and body proportion. METHODS: This was a population-based study based on records of 672,130 pregnancies from the Medical Birth Registry of Norway during 1967-1998. Women with a prior birth, multiple births, those without valid data on the last menstrual period or newborn's crown-heel length, and chronic maternal disease were excluded. RESULTS: In newborns of women with preeclampsia, mean birth weight, crown-heel length, and ponderal index were 4.4%, 0.8%, and 2.6% lower than in births without preeclampsia, respectively. In preterm births, mean differences in birth weight ranged from -11% to -23% against near-equal birth weights in term births. Mean differences in crown-heel length and ponderal index ranged from -1% to -5% and from -5% to -10% before term, respectively. In late preeclampsia, rates of birth weight and crown-heel length above the 90th and 97.5th percentiles and ponderal index above the 97.5th percentile were slightly but significantly higher than in term births without preeclampsia (odds ratios = 1.1-1.5). However, infants born to mothers with preterm preeclampsia were less likely to be heavy, long, or with high ponderal index for gestational age (odds ratios = 0.4-0.6). CONCLUSION: Our results support the hypothesis that preeclampsia is an etiologically heterogeneous disorder that occurs in at least two subsets, one with normal or enhanced placental function, and another involving placental dysfunction and fetal growth restriction, often with asymmetric fetal body proportion, reduced fetal length, and preterm delivery. In future studies, distinguishing between the two subtypes may be important.

Adult↗

PubMed2003

Risk factors for unexplained antepartum fetal death in Norway 1967-1998.

OBJECTIVE: To relate unexplained antepartum fetal death with maternal and fetal characteristics in order to identify risk factors. DESIGN: Population-based study based on records of 1,676,160 singleton births with gestational age > or =28 weeks. Unexplained antepartum fetal death was defined as fetal death before labour without known fetal, placental, or maternal pathology. RESULTS: Although unexplained fetal mortality in general declined from 2.4 per 1000 births in 1967-1976 to 1.6 in 1977-1998, the proportion among all fetal deaths increased from 30% to 43% during the same period of observation. Unexplained fetal death occurred later in gestation than explained. From 39 weeks of gestation, the risk increased progressively to 50/10,000 in women aged > or =35 years and <10/10,000 in women <25 years. In birth order > or =5, the risk was particularly high after 39 weeks of gestation. For birth weight percentile 2.5-9.9 and > or =97.5, unexplained fetal death was four and three times more likely to occur, respectively. We found an additive effect of maternal age and birth weight percentile 2.5-9.9. Women with less than 10 years education had higher risk than women with 13 years or more (OR=1.6). Weaker associations were observed with female gender, unmarried mothers, and winter season. CONCLUSIONS: Unexplained antepartum fetal death occurred later in gestation than explained and was associated with high maternal age, multiparity, low education, and moderately low and high birth weight percentile. The increased risk in post-term pregnancies and the additive effect of maternal age and birth weight percentile 2.5-9.9 suggests that older women would benefit from monitoring of fetal growth.

Birth Weight↗

PubMed2003

Unexplained antepartum fetal death in Norway, 1985-97: diagnostic validation and some epidemiologic aspects.

OBJECTIVE: To validate the diagnosis of an unexplained antepartum fetal death in the Medical Birth Registry of Norway against data obtained from hospital records, alone and combined with autopsy data. To compare epidemiologic characteristics of an unexplained fetal death based on cases recorded by the three data sources. METHODS: Data on unexplained fetal deaths in the Registry were compared with clinical and autopsy data from 108 457 singletons with a gestational age >or= 28 weeks or a birthweight >or= 1000 g delivered in 1985-97 at Haukeland Hospital in Bergen and Aker Hospital in Oslo. RESULTS: Compared with clinical data, the positive and negative predictive values of a Registry diagnosis of an unexplained fetal death were 88% and 86%, respectively, while the sensitivity and specificity were 76% and 93%, respectively. Compared with clinical and autopsy data combined, the positive and negative predictive values of a Registry diagnosis of an unexplained fetal death were 77% and 89%, respectively, while the sensitivity and specificity were 78% and 88%, respectively. High agreement was observed in comparisons between the data sources of risks according to various independent variables. CONCLUSIONS: The validity of a diagnosis of an unexplained antepartum fetal death based on the Medical Birth Registry of Norway is sufficiently high to justify future large-scale epidemiologic studies based on this database.

Adult↗

PubMed2002

Degree of fetal umbilical venous constriction at the abdominal wall in a low-risk population at 20-40 weeks of gestation.

OBJECTIVES: To determine the degree of constriction of the umbilical vein at the abdominal wall in the second half of pregnancy. METHODS: A total of 283 low-risk singleton pregnancies were recruited for a cross-sectional study, and examined once at 20-40 weeks of gestation. Two sets of ultrasound measurements of the umbilical vein were taken: one at the fetal end of the umbilical cord and another at the inlet through the abdominal wall, the umbilical ring. The diameter was determined as an average of >or=5 repeat measurements. The blood velocity was recorded at the same site. RESULTS: The time-averaged maximum venous blood velocity in the cord was low (mean 13-19 cm/s during 20-40 weeks of gestation), and the corresponding mean diameter 3.6-8.2 mm. In contrast, the mean of the venous blood velocity at the umbilical ring was 34-41 cm/s and the diameter was 2.8-5.9 mm during the same period. Of 191 pairs of observations, 41 (21%) had a velocity increment of >or=300 %, which corresponds to a diameter reduction to half or more at the umbilical ring. CONCLUSION: Constriction of the umbilical ring is a common phenomenon in the second half of pregnancy.

Adult↗