Psychedelic drug use and schizotypy in young adults.

Despite recently resurrected scientific interest in classical psychedelics, few studies have focused on potential harms associated with abuse of these substances. In particular, the link between psychedelic use and psychotic symptoms has been debated while no conclusive evidence has been presented. Here, we studied an adult population (n = 1032) with a special focus on young (18-35 years) and healthy individuals (n = 701) to evaluate the association of psychedelic drug use with schizotypy and evidence integration impairment typically observed in psychosis-spectrum disorders. Experimental behavioural testing was performed in a subsample of the subjects (n = 39). We observed higher schizotypy scores in psychedelic users in the total sample. However, the effect size was notably small and only marginally significant when considering young and healthy subjects (Cohen's d = 0.13). Controlling for concomitant drug use, none of our analyses found significant associations between psychedelic use and schizotypal traits. Results from experimental testing showed that total exposure to psychedelics (frequency and temporal proximity of use) was associated with better evidence integration (Cohen's d = 0.13) and a higher sensitivity of fear responses (Cohen's d = 1.05) to the effects instructed knowledge in a reversal aversive learning task modelled computationally with skin conductance response and pupillometry. This effect was present even when controlling for demographics and concomitant drug use. On a group level, however, only difference in sensitivity of fear responses to instructed knowledge reached statistical significance. Taken together, our findings suggest that psychedelic drug use is only weakly associated with psychosis-like symptoms, which, in turn, is to a large extent explained by psychiatric comorbidities and use of other psychoactive substances. Our results also suggest that psychedelics may have an effect on flexibility of evidence integration and aversive learning processes, that may be linked to recently suggested therapeutic effects of psychedelic drugs in non-psychotic psychiatric populations.

Effect of Structured Physical Activity and Nutritional Supplementation on Physical Function in Mobility-Limited Older Adults: Results from the VIVE2 Randomized Trial.

OBJECTIVES: The interactions between nutritional supplementation and physical activity on changes in physical function among older adults remain unclear. The primary objective of this study was to examine the impact of nutritional supplementation plus structured physical activity on 400M walk capacity in mobility-limited older adults across two sites (Boston, USA and Stockholm, Sweden). DESIGN: All subjects participated in a physical activity program (3x/week for 24 weeks), involving walking, strength, balance, and flexibility exercises. Subjects were randomized to a daily nutritional supplement (150kcal, 20g whey protein, 800 IU vitamin D) or placebo (30kcal, non-nutritive). SETTING: Participants were recruited from urban communities at 2 field centers in Boston MA USA and Stockholm SWE. PARTICIPANTS: Mobility-limited (Short Physical Performance Battery (SPPB) ≤9) and vitamin D insufficient (serum 25(OH) D 9 - 24 ng/ml) older adults were recruited for this study. MEASUREMENTS: Primary outcome was gait speed assessed by the 400M walk. RESULTS: 149 subjects were randomized into the study (mean age=77.5±5.4; female=46.3%; mean SPPB= 7.9±1.2; mean 25(OH)D=18.7±6.4 ng/ml). Adherence across supplement and placebo groups was similar (86% and 88%, respectively), and was also similar across groups for the physical activity intervention (75% and 72%, respectively). Both groups demonstrated an improvement in gait speed with no significant difference between those who received the nutritional supplement compared to the placebo (0.071 and 0.108 m/s, respectively (p=0.06)). Similar effects in physical function were observed using the SPPB. Serum 25(OH)D increased in supplemented group compared to placebo 7.4 ng/ml versus 1.3 ng/ml respectively. CONCLUSION: Results suggest improved gait speed following physical activity program with no further improvement with added nutritional supplementation.

When and where do hip fractures occur? A population-based study.

UNLABELLED: We investigated the effects of socio-demographic and health factors on timing and location of hip fracture among 484 subjects. Time of fracture varied between community dwellers and residential care facility dwellers, and in relation to subjects' psychotropic drug status. Indoor hip fracture incidence increased on snow-covered days. INTRODUCTION: This paper aims to describe the timing and whereabouts of hip fracture cases in a population-based setting and to relate these factors with residential and health status, seasonal variation, and snow-covered ground. METHODS: We consecutively included 484 incident hip fracture events (age ≥50 years) admitted to a Swedish orthopedic department during a 1-year period. Data concerning socio-demographic details, fall location, time of fracture, comorbidity, and medications were collected from in-patient medical records and through patient or caregiver interviews. RESULTS: The expected peak in fracture occurrence during daytime was observed among community dwellers but not among subjects living in residential care. Hip fracture was twice as likely to occur during nighttime hours among psychotropic drug users (adjusted odds ratio (Adj. OR), 2.20; 95% confidence interval (CI), 1.12-4.30) compared to those not receiving these medications. Subjects without dementia, taking psychotropic drugs, were also more likely to fracture during nighttime hours (Adj. OR, 2.91; 95% CI, 1.40-6.0). We observed an increase in indoor hip fracture incidence on snow-covered days among community dwellers (incidence rate ratio, 1.34; 95% CI, 1.02-1.74). We observed only a weak seasonal trend in hip fracture incidence, based on month, among community dwellers who fractured indoors. CONCLUSIONS: Special attention and possibly fall-preventive efforts should be directed not only toward those living in residential care facilities but also toward community-dwelling subjects taking psychotropic drugs since these groups have a higher incidence of nighttime hip fracture. Further research aiming to explain the seasonal variation of indoor fracture incidence among community dwellers is warranted.

Calculations of mechanisms for balance control during narrow and single-leg standing in fit older adults: A reliability study.

For older people balance control in standing is critical for performance of activities of daily living without falling. The aims were to investigate reliability of quantification of the usage of the two balance mechanisms M(1) 'moving the centre of pressure' and M(2) 'segment acceleration' and also to compare calculation methods based on a combination of kinetic (K) and kinematic (Km) data, (K-Km), or Km data only concerning M(2). For this purpose nine physically fit persons aged 70-78 years were tested in narrow and single-leg standing. Data were collected by a 7-camera motion capture system and two force plates. Repeated measure ANOVA and Tukey's post hoc tests were used to detect differences between the standing tasks. Reliability was estimated by ICCs, standard error of measurement including its 95% CI, and minimal detectable change, whereas Pearson's correlation coefficient was used to investigate agreement between the two calculation methods. The results indicated that for the tasks investigated, M(1) and M(2) can be measured with acceptable inter- and intrasession reliability, and that both Km and K-Km based calculations may be useful for M(2), although Km data may give slightly lower values. The proportional M(1):M(2) usage was approximately 9:1, in both anterio-posterior (AP) and medio-lateral (ML) directions for narrow standing, and about 2:1 in the AP and of 1:2 in the ML direction in single-leg standing, respectively. In conclusion, the tested measurements and calculations appear to constitute a reliable way of quantifying one important aspect of balance capacity in fit older people.

Ischaemic pre-conditioning means an increased adenosine metabolism with decreased glycolytic flow in ischaemic pig myocardium.

BACKGROUND: Ischaemic pre-conditioning (IP) is a potent protective mechanism for limiting the myocardial damage due to ischaemia. It is not fully known as to how IP protects. The metabolism of adenosine may be an important mechanistic component. We study the role of adenosine turnover together with glycolytic flow in ischaemic myocardium subjected to IP. METHODS: An acute myocardial ischaemia pig model was used, with microdialysis sampling of some metabolites (lactate, adenosine, glucose, glycerol, taurine) of ischaemic myocardium. An IP group was compared with a control group before and during a prolonged ischaemia. ¹4C-labelled adenosine and glucose were infused through microdialysis probes, and lactate, ¹4C-labelled lactate, glucose, taurine and glycerol were analysed in the effluent. The glycogen content in myocardial biopsies was determined. RESULTS: The ¹4C-adenosine metabolism was higher as there was a higher production of ¹4C-lactate in IP animals compared with the controls. The glycolytic flow, measured as myocardial lactate formation, was retarded during prolonged ischaemia in IP animals. Myocardial free glucose and glycogen content decreased during the prolonged ischaemia in both groups, with higher free glucose in the IP group. We confirmed the protective effects of IP with lower myocardial concentrations of markers for cellular damage (glycerol). CONCLUSIONS: This association between increased adenosine turnover and decreased glycolytic flow during prolonged ischaemia in response to IP can possibly be explained by the competitive effect for the metabolites from both glucose and adenosine metabolism for entering glycolysis. We conclude that this study provides support for an energy-metabolic explanation for the protective mechanisms of IP.

Metabolic responses in ischemic myocardium after inhalation of carbon monoxide.

BACKGROUND: To clarify the mechanisms of carbon monoxide (CO) tissue-protective effects, we studied energy metabolism in an animal model of acute coronary occlusion and pre-treatment with CO. METHODS: In anesthetized pigs, a coronary snare and microdialysis probes were placed. CO (carboxyhemoglobin 5%) was inhaled for 200 min in test animals, followed by 40 min of coronary occlusion. Microdialysate was analyzed for lactate and glucose, and myocardial tissue samples were analyzed for adenosine tri-phosphate, adenosine di-phosphate, and adenosine mono-phosphate. RESULTS: Lactate during coronary occlusion was approximately half as high in CO pre-treated animals and glucose levels decreased to a much lesser degree during ischemia. Energy charge was no different between groups. CONCLUSIONS: CO in the low-doses tested in this model results in a more favorable energy metabolic condition in that glycolysis is decreased in spite of maintained energy charge. Further work is warranted to clarify the possible mechanistic role of energy metabolism for CO protection.

Lactate concentration in umbilical cord blood is gestational age-dependent: a population-based study of 17 867 newborns.

OBJECTIVE: To study the influence of gestational age on lactate concentration in arterial and venous umbilical cord blood at birth and to define gestational age-specific reference values for lactate in vigorous newborns. DESIGN: Population-based comparative. SETTING: University hospitals. SAMPLE: Vigorous newborns with validated umbilical cord blood samples. MATERIAL AND METHODS: From 2000 to 2004, routine cord blood gases, lactate and obstetric data from two university hospitals were available for 17 867 newborns from gestational week 24 to 43. After validation of blood samples and inclusion only of singleton pregnancies aimed for vaginal delivery, 10 700 women remained. Among those, reference values were defined in 10 169 vigorous newborns, that is in newborns with a 5-minute Apgar score corresponding to the gestational age-specific median value minus 1 point score, or better. MAIN OUTCOME MEASURES: Cord lactate concentration relative to gestational age. RESULTS: The arterial and venous lactate concentrations increased monotonously with gestational age from 34 weeks. Considerable differences were found between mean and median values, but after logarithmic transformation the log-lactate values were normally distributed. Simple linear regression analysis showed a significant association between the log-lactate values and gestational age (P < 10(-6), R(2)= 0.024). Reference curves were constructed after anti-logarithmic transformation. Both the gestational age and the time of the second stage of labour influenced, independently of each other, the lactate concentrations. CONCLUSIONS: Lactate concentrations in arterial and venous umbilical cord blood are increasing significantly with advancing gestational age.

Daily eating events among co-living and single-living, diseased older men.

OBJECTIVES: To analyse, describe and compare the frequency and energy intake of eating events, including specific food items, among diseased older men living in ordinary housing. DESIGN: Descriptive and explorative. SETTING: Interviews were performed in the participants' home. PARTICIPANTS: Thirty-five co-living and 26 single-living men, 64-88 years of age. Participants had one of three chronic diseases associated with difficulties in buying and preparing food and with difficulties related to the meal situation: Parkinson's disease, rheumatoid arthritis or stroke. MEASUREMENTS: A repeated 24-h recall was used to assess food intake and meal patterns. RESULTS: Eating events were distributed over a 24-h period. Co-living men had a higher (p=0.001) number of eating events/day; both hot and cold eating events were consumed more frequently. There was no difference between groups concerning energy intake. Co-living men more often had hot eating events cooked from raw ingredients (p=0.001) and a greater mix of vegetables/roots (p=0.003) included in such eating events. CONCLUSION: Single-living men may constitute a vulnerable group from a nutritional perspective, while co-living men, besides the pleasure of eating with another person, seem to get support with food and eating events from their partners. Hence, the group of single-living men, particularly those with a disability, should receive particular attention with regard to possible food-related difficulties.

Hypoxia-independent apoptosis in neural cells exposed to carbon monoxide in vitro.

The neurotoxic effects of carbon monoxide (CO) are well known. Brain hypoxia due to the binding of CO to hemoglobin is a recognized cause of CO neurotoxicity, while the direct effect of CO on intracellular targets remains poorly understood. In the present study, we have investigated the pathways leading to neural cell death induced by in vitro exposure to CO using a gas exposure chamber that we have developed. Mouse hippocampal neurons (HT22) and human glial cells (D384) were exposed to concentrations of CO ranging from 300 to 1000 ppm in the presence of 20% oxygen. Cytotoxicity was observed after 48 h exposure to 1000 ppm, corresponding to approximately 1 microM CO in the cultured medium, as measured by gas chromatography. CO induced cell death with characteristic features of apoptosis. Exposed cells exhibited loss of mitochondrial membrane potential, release of cytochrome c into the cytosol, nuclei with chromatin condensation, and exposure of phosphatidyl serine on the external leaflet of the plasma membrane. CO also triggered activation of caspase and calpain proteases. Pre-incubation with either the pancaspase inhibitor Z-VAD-fmk (20 microM) or the calpain inhibitor E64d (25 microM) reduced by 50% the occurrence of apoptosis. When pre-incubating the cells with the two inhibitors together there was an additional reduction in the number of cells with apoptotic nuclei. These data suggest that CO causes apoptosis via activation of parallel proteolytic pathways involving both caspases and calpains. Furthermore, pre-treatment with the antioxidant MnTBAP (100 microM) significantly reduced the number of apoptotic nuclei, pointing to a critical role of oxidative stress in CO toxicity.

Antibody levels in adult patients with coeliac disease during gluten-free diet: a rapid initial decrease of clinical importance.

OBJECTIVE: Analysis of antibodies against tissue transglutaminase (tTG) has been shown valuable in the diagnosis of coeliac disease (CD) but how quickly serum titres decrease after introduction of a gluten-free diet (GFD) is not known in adults. CD is a well-recognized disorder amongst the general population and many persons try a GFD for fairly vague symptoms before they seek medical advice. Therefore, it is important to determine the time that the serologic tests remain predictive of the disease after the introduction of a GFD. METHODS: Sera were taken from 22 consecutively biopsy-proven adult patients with CD in connection with the diagnostic biopsy. The patients were followed for 1 year and sera were taken after 1, 3, 6 and 12 months after start of a GFD. Sera were stored at -20 degrees C and analysed for IgA antibodies against gliadin, endomysium and two different commercial tTG assays based on recombinant human tTG (tTGrh) and guinea-pig liver (tTGgp). RESULTS: Twenty patients could be followed during GFD and all antibody titres fell sharply within 1 month after introduction of a GFD and continued to decline during the survey interval. Thirty days after beginning the diet only 58, 84, 74 and 53% of all patients had positive antibody levels of tTGrh, tTGgp, EmA and AGA respectively. CONCLUSIONS: As the antibodies used to confirm the diagnosis of CD fall rapidly and continue to decline following the introduction of a GFD, it is important that health care providers carefully inquire about the possibility of self-prescribed diets before patients sought medical attention.

Methods of choice for diagnostic antinuclear antibody (ANA) screening: benefit of adding antigen-specific assays to immunofluorescence microscopy.

OBJECTIVES: To evaluate and compare the performances of three enzyme-immunoassays (EIAs) and a double radial immunodiffusion (DRID) test in addition to immunofluorescence (IF) microscopy for routine laboratory screening of patient sera sent for antinuclear antibody (ANA) analysis. METHODS: 3079 consecutive patient sera sent for routine testing of ANA were analysed by IF microscopy on HEp-2 cells (IF-ANA), three different ANA-EIAs, and a DRID test for antibodies against extractable nuclear antigens. The IF-ANA and DRID tests were regarded as reference methods. RESULTS: By IF-ANA and/or DRID, 375 sera (12%) turned out ANA-positive. A further 171 sera (6%) were positive by EIA, but could not be confirmed either by IF microscopy or DRID. 32 of the 375 ANA-positive (9%) sera were negative by IF microscopy, but had precipitating antibodies against Ro/SS-A (52 and/or 60 kD). CONCLUSIONS: Different assays for ANA analysis give overlapping results to a certain extent, but are by no means interchangeable. Thus, different ANA tests reflect different aspects of these autoantibodies. The diagnostic utility of ANA testing still mainly refers to IF-microscopy and precipitin tests. IF-ANA should not be abandoned as the golden standard in clinical routine, until diagnostic and classification criteria for systemic lupus erythematosus and other systemic inflammatory autoimmune diseases have been revised. However, in addition we strongly advocate that a specific test for anti-Ro/SS-A antibodies is always included.

Childhood malignancy and maternal diabetes or other auto-immune disease during pregnancy.

Among 4380 children born in 1987-1997 of women with a diagnosis of diabetes and alive at the age of one, 10 were registered in the Swedish Cancer Registry before the end of 1998. The odds ratio for having a childhood cancer after maternal diabetes, stratified for year of birth, maternal age, parity, multiple birth, and 500 g birth weight class was 2.25 (95%CI 1.22-4.15). Among 5842 children born during the period 1973-1997 whose mothers had other auto-immune diseases (SLE, rheumatoid arthritis, Crohn, ulcerous colitis, multiple sclerosis or thyroiditis), the number of observed childhood cancers (9) was close to that expected (8.5). Maternal diabetes but not other auto-immune diseases may be a risk factor for childhood cancer.

Use of multivitamins and folic acid in early pregnancy and multiple births in Sweden.

Folic acid is recommended to reduce the risk of neural tube defects and other congenital malformations. Data from the Swedish Medical Birth Registry were used to study frequency of twinning in women who in early pregnancy reported the use of folic acid. Women (n = 2,569) who in early pregnancy reported the use of folic acid had an increased rate of twin deliveries after consideration of maternal age and of length of involuntary childlessness, both variables being significant confounders. The effect of folic acid was seen also in women who did not report involuntary childlessness. A similar but not statistically significant trend was seen after use of multivitamins without simultaneous use of folic acid tablets (n = 1,979). The increased risk seems to be limited to dizygotic twinning (relative risk = 2.13, 95% CI 1.64-2.74). If this association is causal, wide-spread supplementation with folic acid may represent a hazard larger than the postulated beneficial effect on neural tube defects, at least in low-risk areas.

Association between maternal pre-existing or gestational diabetes and health problems in children.

UNLABELLED: There is general consensus that children of women with pre-existing diabetes mellitus (PDM) have an increased risk of malformations and neurodevelopmental problems. Whether this is also true for children of women with gestational diabetes mellitus (GDM) is a matter of debate. This study investigated inpatient hospital care up to 10 y of age of children born to GDM and PDM women as a rough estimate of child morbidity. Hospital care of children born to 82,684 GDM women, 3,874 PDM women and 1,213,957 controls was compared by linking the Swedish Medical Birth Registry with the Hospital Discharge Registry. Similar comparisons were performed in a local well-controlled group of 326 children born to GDM women in the Lund area. Children of PDM women and to a lesser degree children of GDM women had a statistically significant increase in hospitalizations, evident at least up to 10 y of age. Significantly increased risks of hospitalization were found for neurological/developmental disorders [odds ratio (OR) 2.30 and 1.36 for PDM and GDM, respectively)], malformations (OR 2.05 and 1.23), infections (OR 1.56 and 1.20) and accidents (OR 1.32 and 1.14). CONCLUSION: The high hospitalization rates of these children indicate an increased morbidity, including neurodevelopmental disorders.

Impaired glucose tolerance associated with adverse pregnancy outcome: a population-based study in southern Sweden.

OBJECTIVE: We conducted a population-based study of maternal and neonatal characteristics and delivery complications in relation to the outcome of a 75-g, 2-hour oral glucose tolerance test at 25 to 30 weeks' gestation. STUDY DESIGN: An oral glucose tolerance test was offered to pregnant women in a geographically defined population. Pregnancy outcome was analyzed according to the test result. RESULTS: Among women delivered at Lund Hospital, we identified 4526 women with an oral glucose tolerance value of <7.8 mmol/L (<140 mg/dL), 131 women with a value of 7.8 to 8.9 mmol/L (140-162 mg/dL), and 116 women with gestational diabetes (> or =9.0 mmol/L [> or =162 mg/dL]). A further 28 cases of gestational diabetes were identified, giving a prevalence of 1.2%. An increased rate of cesarean delivery and infant macrosomia was observed in the group with a glucose tolerance value of 7.8 to 8.9 mmol/L (140-162 mg/dL) and in the gestational diabetes group. Advanced maternal age and high body mass index were risk factors for increased oral glucose tolerance values in 12,657 screened women in the area. CONCLUSION: The study stresses the significance of moderately increased oral glucose tolerance values.

Congenital malformations among infants whose mothers had gestational diabetes or preexisting diabetes.

BACKGROUND: Diabetes type 1 is associated with an increased risk for infant congenital malformations. It is debated whether this is true also at gestational diabetes. AIMS: To study occurrence of congenital malformations in infants whose mothers had preexisting or gestational diabetes. STUDY DESIGN: A register study covering over 1.2 million Swedish births in 1987-1997 based on the Swedish health registries. SUBJECTS: We identified from the Medical Birth Registry 3864 infants born of women with preexisting diabetes and 8688 infants born of women with gestational diabetes. OUTCOMES MEASURES: Congenital malformations identified in the Medical Birth Registry, the Registry of Congenital Malformations, and the Hospital Discharge Registry. The rates of congenital malformations among these infants was compared with the population rates. RESULTS: At preexisting diabetes, the total malformation rate was 9.5% while the rate at gestational diabetes was similar to the population rate, 5.7%. At preexisting diabetes, certain conditions were more common than expected: orofacial clefts, cardiovascular defects, oesophageal/intestinal atresia, hypospadias, limb reduction defects, spine malformations, and polydactyly. For some of these conditions, an excess was found also for infants whose mothers had gestational diabetes. Infants with multiple malformations were in excess at preexisting diabetes but not at gestational diabetes but the specific type of malformations involved were similar in the two diabetes groups. CONCLUSIONS: It is suggested that in the group of gestational diabetes exists a subgroup with an increased risk for a diabetes embryopathy, perhaps due to preexisting but undetected diabetes type 2.

Acupuncture for lower back and pelvic pain in late pregnancy: a retrospective report on 167 consecutive cases.

Adverse and analgesic effects of acupuncture during the second and third trimesters of pregnancy were studied retrospectively in an observational study including 167 consecutive patients with lower back pain, pelvic pain, or both. In each patient acupuncture was given on at least two different occasions by three manual stimulations of two or more acupuncture or tender points, mainly LR-3 and LI-4 together with local tender points, at 15-min intervals. Possible adverse and analgesic effects were assessed by the midwife responsible for the acupuncture given in each patient. There were no abortions and no influence on the delivery course of the infants, but transient premature labor was observed during the fourth stimulation carried out in the 15th gestational week in one woman. Other possible adverse effects, like transient dizziness or tiredness, were reported in 35 patients (21%). Analgesia, as assessed by midwives involved, was good or excellent in 72% of patients. Acupuncture seems to be safe and effective for pain relief in lower back pain, pelvic pain, or both during the second and third trimesters of pregnancy. Nevertheless, prospective randomized studies are needed to confirm these findings.

Recombining germline-derived CDR sequences for creating diverse single-framework antibody libraries.

We constructed a single-chain Fv antibody library that permits human complementarity-determining region (CDR) gene fragments of any germline to be incorporated combinatorially into the appropriate positions of the variable-region frameworks VH-DP47 and VL-DPL3. A library of 2 x 109 independent transformants was screened against haptens, peptides, carbohydrates, and proteins, and the selected antibody fragments exhibited dissociation constants in the subnanomolar range. The antibody genes in this library were built on a single master framework into which diverse CDRs were allowed to recombine. These CDRs were sampled from in vivo-processed gene sequences, thus potentially optimizing the levels of correctly folded and functional molecules, and resulting in a molecule exhibiting a lower computed immunogenicity compared to naive immunoglobulins. Using the modularized assembly process to incorporate foreign sequences into an immunoglobulin scaffold, it is possible to vary as many as six CDRs at the same time, creating genetic and functional variation in antibody molecules.

Asthma during pregnancy--a population based study.

To study delivery outcome in women with asthma, using Swedish health registers. Women with asthma were identified in two ways: by information in interviews performed by midwives at the pregnant woman's first visit to antenatal care, and by linkage between a medical birth register and a hospital discharge register, identifying women who had been hospitalized for asthma and also had a delivery. Births between 1984 and 1995 were studied. An increased risk for preterm birth and low birth weight was seen, possibly co-varying with disease severity. Also a significant increase in pregnancies of more than 41 weeks duration was noticed. An increase in infant death but not in congenital malformations rate was observed. An association with preeclampsia, gestational diabetes, and infant hypoglycemia was verified. Maternal asthma appears to be a risk factor for preterm and postterm births and increases the risk for some pregnancy complications.