Angiogenic factors and the risk of adverse outcomes in women with suspected preeclampsia.

BACKGROUND: An imbalance in circulating angiogenic factors plays a central role in the pathogenesis of preeclampsia. METHODS AND RESULTS: We prospectively studied 616 women who were evaluated for suspected preeclampsia. We measured plasma levels of antiangiogenic soluble fms-like tyrosine kinase 1 (sFlt1) and proangiogenic placental growth factor (PlGF) at presentation and examined for an association between the sFlt1/PlGF ratio and subsequent adverse maternal and perinatal outcomes within 2 weeks. The median sFlt1/PlGF ratio at presentation was elevated in participants who experienced any adverse outcome compared with those who did not (47.0 [25th-75th percentile, 15.5-112.2] versus 10.8 [25th-75th percentile, 4.1-28.6]; P<0.0001). Among those presenting at <34 weeks (n=167), the results were more striking (226.6 [25th-75th percentile, 50.4-547.3] versus 4.5 [25th-75th percentile, 2.0-13.5]; P<0.0001), and the risk was markedly elevated when the highest sFlt1/PlGF ratio tertile was compared with the lowest (odds ratio, 47.8; 95% confidence interval, 14.6-156.6). Among participants presenting at <34 weeks, the addition of sFlt1/PlGF ratio to hypertension and proteinuria significantly improved the prediction for subsequent adverse outcomes (area under the curve, 0.93 for hypertension, proteinuria, and sFlt1/PlGF versus 0.84 for hypertension and proteinuria alone; P=0.001). Delivery occurred within 2 weeks of presentation in 86.0% of women with an sFlt1/PlGF ratio ≥85 compared with 15.8% of women with an sFlt1/PlGF ratio <85 (hazard ratio, 15.2; 95% confidence interval, 8.0-28.7). CONCLUSIONS: In women with suspected preeclampsia presenting at <34 weeks, circulating sFlt1/PlGF ratio predicts adverse outcomes occurring within 2 weeks. The accuracy of this test is substantially better than that of current approaches and may be useful in risk stratification and management. Additional studies are warranted to validate these findings.

Circulating anti-angiogenic factors during hypertensive pregnancy and increased risk of respiratory distress syndrome in preterm neonates.

OBJECTIVE: To test the hypothesis that high circulating concentrations of maternal anti-angiogenic factors are associated with increased risk of respiratory distress syndrome (RDS). STUDY DESIGN: This is a nested case-control study of nulliparous women who delivered less than 37 weeks of gestation within the Calcium for Preeclampsia Prevention (CPEP) trial. The study included 116 women with preeclampsia or gestational hypertension and 323 normotensive controls. Soluble fms-like tyrosine kinase 1 (sFlt1), placental growth factor (PlGF) and soluble endoglin (sEng) in maternal serum were measured at 21-32 weeks of gestation. RESULTS: Preterm infants born to hypertensive mothers were more likely to develop RDS (22.5% vs. 20.9%, p = 0.03). After adjustment for gestational age at delivery, the odds ratio for the relationship between hypertension in pregnancy and RDS was 2.18 (95% CI 1.08-4.39). In hypertensive pregnancies women whose infants developed RDS had significantly higher circulating mean sFlt1 levels during midpregnancy (21-32 weeks of gestation) even after adjustment for gestational age at delivery (21,516 pg/mL vs. 7,000 pg/mL, p = 0.01). CONCLUSIONS: Preterm preeclampsia and gestational hypertension, characterized by high circulating levels of sFlt1, are associated with a twofold increased risk of RDS in infants delivered before 37 weeks. Among women with these hypertensive pregnancies circulating sFlt1 concentrations during midpregnancy were substantially higher in women whose infants developed RDS.

Folate and vitamin B12 in idiopathic male infertility.

Although methylenetetrahydrofolate reductase, a folate enzyme gene, has been associated with idiopathic male infertility, few studies have examined other folate-related metabolites and genes. We investigated whether idiopathic male infertility is associated with variants in folate, vitamin B(12) (B12) and total homocysteine (tHcy)-related genes and measured these metabolites in blood. We conducted a case-control study that included 153 men with idiopathic infertility and 184 fertile male controls recruited at the Fertility Center and Antenatal Care Center, University Hospital, Malmö and Lund, Sweden. Serum folate, red cell folate (RCF), serum B12, plasma tHcy and semen quality were measured. Subjects were genotyped for 20 common variants in 12 genes related to folate/B12/homocysteine metabolism. Metabolite concentrations and genotype distributions were compared between cases and controls using linear and logistic regression with adjustment for covariates. The phosphatidylethanolamine N-methyltransferase (PEMT) M175V and TCblR rs173665 polymorphisms were significantly associated with infertility (P=0.01 and P=0.009, respectively), but not with semen quality. Among non-users of supplements, infertile men had lower serum folate concentrations than fertile men (12.89 vs. 14.73 nmol l(-1); P=0.02), but there were no significant differences in RCF, B12 or tHcy. Folate, B12 and tHcy concentrations were not correlated with any semen parameters. This study provides little support for low folate or B12 status in the pathogenesis of idiopathic male infertility. Although additional data are needed to confirm these initial findings, our results suggest that PEMT and TCblR, genes involved in choline and B12 metabolism, merit further investigation in idiopathic male infertility.

Preeclampsia and the risk of large-for-gestational-age infants.

OBJECTIVE: We sought to compare the risk of giving birth to large-for-gestational-age (LGA) infants in women with and without preeclampsia, after adjustment for obesity and glucose intolerance. STUDY DESIGN: We conducted secondary analysis of a prospective database of pregnant women with and without preeclampsia who delivered infants from 1998 through 2006 at Massachusetts General Hospital (n = 17,465). RESULTS: The risk of LGA was similar in women with and without preeclampsia (odds ratio, 0.81; 95% confidence interval, 0.59-1.14). After adjustment for body mass index, glucose intolerance, and other factors, the risk of LGA was significantly lower in women with preeclampsia compared to those without preeclampsia (odds ratio, 0.69; 95% confidence interval, 0.49-0.96). Stratified analysis in groups with a higher risk of LGA revealed that preeclampsia has a similar effect on the risk of LGA regardless of maternal obesity, glucose intolerance, parity, and race. CONCLUSION: Preeclampsia appears to be characterized by reduced, and not increased, fetal growth.

Pathogenesis of preeclampsia.

Preeclampsia is a systemic syndrome that occurs in 3 to 5% of pregnant women and classically manifests as new-onset hypertension and proteinuria after 20 weeks of gestation. Preeclampsia is a leading cause of maternal and neonatal morbidity and mortality. The only known cure is delivery of the placenta. Recent discoveries, however, have led to important advances in understanding the pathogenesis of the condition. Placental antiangiogenic factors are upregulated and disrupt the maternal endothelium. This change in the normal angiogenic balance toward an antiangiogenic state can result in hypertension, proteinuria, glomerular endotheliosis, HELLP (hemolysis, elevated liver enzymes, and low platelets) syndrome, and cerebral edema-the clinical signs of preeclampsia and eclampsia. The regulation of these antiangiogenic factors in the placenta is unknown. The recent discoveries of upregulated antiangiogenic factors provide promise for future testing to predict and diagnose preeclampsia as well as therapeutic targets for amelioration of the clinical disease.

The use of angiogenic biomarkers to differentiate non-HELLP related thrombocytopenia from HELLP syndrome.

OBJECTIVE: Preeclampsia (PE) is diagnosed using clinical criteria and in atypical cases the diagnosis may be inaccurate as there are no specific tests to confirm or exclude PE. This study sought to evaluate the utility of angiogenic biomarkers, sFlt1, sEng and PlGF to distinguish patients with gestational thrombocytopenia and immune thrombocytopenic purpura (ITP) from patients with thrombocytopenia resulting from the HELLP (hemolysis, elevated liver enzymes and low platelets) syndrome, a complication of severe PE. METHODS: Serum was collected and the angiogenic biomarkers of patients with ITP and gestational thrombocytopenia (N = 9) were compared to patients with HELLP (N = 11) and PE (N = 11). Circulating levels of these angiogenic biomarkers were also compared by gestational age to 1564 randomly selected normotensive women from the Calcium for Preeclampsia Prevention study. RESULTS: Patients with non-HELLP thrombocytopenia had lower sFlt1 (7.3 +/- 3.8 ng/ml vs. 15.5 +/- 5 ng/ml, P < 0.001), lower sEng (8.7 +/- 3.6 vs. 34 +/- 17, P < 0.001) and higher PlGF (484 +/- 412 vs. 66.3 +/- 44, P = 0.003) than patients with HELLP syndrome. Angiogenic factor abnormalities in patients with PE were similar to patients with HELLP syndrome, suggesting a common pathogenesis. Patients with non-HELLP thrombocytopenia had angiogenic profiles similar to normotensive controls, whereas patients with HELLP syndrome had levels higher than the 90th percentile for sFlt1 and sEng and lower than the 10th percentile for PlGF. CONCLUSIONS: Angiogenic biomarkers may be useful in excluding conditions that mimic PE.

Sperm chromatin structure assay as an independent predictor of fertility in vivo: a case-control study.

Standard sperm parameters have a limited power for prediction of the chance of natural conception. Recent studies have indicated that the sperm chromatin structure assay (SCSA) DNA fragmentation index (DFI), a measure for the fraction of sperms with DNA damage, is associated with fertility in vivo. The aim of this study was to evaluate the value of this parameter for prediction of infertility. One hundred and twenty-seven men from infertile couples with no known female factor and 137 men with proven fertility were included. Semen analysis was performed as recommended by the WHO. DFI was assessed using SCSA. Logistic binary regression was used to compute the odds ratios (OR) for infertility. As compared with men with a DFI <10%, men with a DFI between 10% and 20% had an increased risk for infertility (OR 2.5, 95% CI: 1.0-6.1). This was also true for men with a DFI >20% (OR 8.4; 95% CI: 3.0-23). In men with normal standard semen parameters (sperm concentration, motility and morphology) the OR for infertility was increased with DFI >20% (OR 5.1, 95% CI: 1.2-23), whereas if one of the standard semen parameters was abnormal, the OR for infertility was increased already at DFI above 10% (OR 16, 95% CI: 4.2-60). We conclude that SCSA DFI adds to the value of semen analysis in prediction of the chance of natural conception.

Pre-eclampsia, soluble fms-like tyrosine kinase 1, and the risk of reduced thyroid function: nested case-control and population based study.

OBJECTIVE: To determine if pre-eclampsia is associated with reduced thyroid function during and after pregnancy. DESIGN: Nested case-control study during pregnancy and population based follow-up study after pregnancy. SETTING: Calcium for Pre-eclampsia Prevention trial of healthy pregnant nulliparous women in the United States during 1992-5, and a Norwegian population based study (Nord-Trondelag Health Study or HUNT-2) during 1995-7 with linkage to the medical birth registry of Norway. PARTICIPANTS: All 141 women (cases) in the Calcium for Pre-eclampsia Prevention trial with serum measurements before 21 weeks' gestation (baseline) and after onset of pre-eclampsia (before delivery), 141 normotensive controls with serum measurements at similar gestational ages, and 7121 women in the Nord-Trondelag Health Study whose first birth had occurred in 1967 or later and in whom serum levels of thyroid stimulating hormone had been subsequently measured. MAIN OUTCOME MEASURES: Thyroid function tests and human chorionic gonadotrophin and soluble fms-like tyrosine kinase 1 concentrations in the Calcium for Pre-eclampsia Prevention cohort and odds ratios for levels of thyroid stimulating hormone above the reference range, according to pre-eclampsia status in singleton pregnancies before the Nord-Trondelag Health Study. RESULTS: In predelivery specimens of the Calcium for Pre-eclampsia Prevention cohort after the onset of pre-eclampsia, thyroid stimulating hormone levels increased 2.42 times above baseline compared with a 1.48 times increase in controls. The ratio of the predelivery to baseline ratio of cases to that of the controls was 1.64 (95% confidence interval 1.29 to 2.08). Free triiodothyronine decreased more in the women with pre-eclampsia than in the controls (case ratio to control ratio 0.96, 95% confidence interval 0.92 to 0.99). The predelivery specimens but not baseline samples from women with pre-eclampsia were significantly more likely than those from controls to have concentrations of thyroid stimulating hormone above the reference range (adjusted odds ratio 2.2, 95% confidence interval 1.1 to 4.4). Both in women who developed pre-eclampsia and in normotensive controls the increase in thyroid stimulating hormone concentration between baseline and predelivery specimens was strongly associated with increasing quarters of predelivery soluble fms-like tyrosine kinase 1 (P for trend 0.002 and <0.001, respectively). In the Nord-Trondelag Health Study, women with a history of pre-eclampsia in their first pregnancy were more likely than other women (adjusted odds ratio 1.7, 95% confidence interval 1.1 to 2.5) to have concentrations of thyroid stimulating hormone above the reference range (>3.5 mIU/l). In particular, they were more likely to have high concentrations of thyroid stimulating hormone without thyroid peroxidase antibodies (adjusted odds ratio 2.6, 95% confidence interval 1.3 to 5.0), suggesting hypothyroid function in the absence of an autoimmune process. This association was especially strong (5.8, 1.3 to 25.5) if pre-eclampsia had occurred in both the first and the second pregnancies. CONCLUSION: Increased serum concentration of soluble fms-like tyrosine kinase 1 during pre-eclampsia is associated with subclinical hypothyroidism during pregnancy. Pre-eclampsia may also predispose to reduced thyroid function in later years.

Angiogenic factor abnormalities and fetal demise in a twin pregnancy.

BACKGROUND: An otherwise healthy 31-year-old gravida 2 para 1 woman with a spontaneous dichorionic, diamniotic twin pregnancy presented with hypertension, nephrotic syndrome and renal insufficiency at 19 weeks' gestation. Fetal ultrasound revealed severe intrauterine growth restriction of one fetus and measurement of serum anti-angiogenic and angiogenic factors were consistent with a profound anti-angiogenic state. After one fetus died and the placenta became increasingly echogenic, the patient improved clinically, and weekly ultrasound assessments of the intact co-twin from 22 weeks onwards demonstrated symmetrical fetal growth along the 10th centile. Repeat serum angiogenic factors at 24 weeks' gestation revealed considerable improvement of the anti-angiogenic state and paralleled resolution of the clinical syndrome. INVESTIGATIONS: Physical examination, laboratory evaluations including full blood count, liver function tests, electrolytes, renal function tests, screening for glomerular-based disease, 24-h urine collection for total protein, analysis of serum anti-angiogenic and angiogenic factors, fetal ultrasonography and placental Doppler examination. DIAGNOSIS: Spontaneous resolution of early-onset pre-eclampsia after single fetal demise in a twin pregnancy. MANAGEMENT: Labetalol was given to treat hypertension and furosemide was given as needed for edema. The patient was closely followed up throughout pregnancy in a combined nephrology/obstetrics outpatient clinic.

Maternal serum theobromine and the development of preeclampsia.

BACKGROUND: Preeclampsia, a disorder with prominent cardiovascular manifestations, is a cause of maternal, fetal, and infant morbidity and mortality. Chocolate contains compounds that may promote cardiovascular health. A recent study found chocolate consumption during pregnancy, and, particularly, increasing cord serum concentration of theobromine (the primary methylxanthine alkaloid in chocolate), to be associated with reduced occurrence of preeclampsia. METHODS: We studied 2769 women who comprised the control group from a case-control study of caffeine metabolites and spontaneous abortion nested within the Collaborative Perinatal Project. These women were pregnant between 1959 and 1966, with liveborn infants of at least 28 weeks' gestation. Serum was drawn at <20 weeks and >26 weeks' gestation, and assayed for theobromine by high-performance liquid chromatography. Odds ratios (ORs) for preeclampsia were estimated using logistic regression, and adjusted for age, education, prepregnant weight, race, parity, smoking, and gestation at blood draw. RESULTS: Preeclampsia occurred in 68 (2.9%) of 2105 eligible women. Adjusted ORs for preeclampsia were near unity across most third-trimester theobromine concentrations. Adjusted ORs for preeclampsia according to theobromine concentration in serum at <20 weeks' gestation increased with increases in concentration, although estimates were imprecise. CONCLUSION: This study does not support the previous finding that chocolate consumption is associated with a reduced occurrence of preeclampsia. Unmeasured confounding or reverse causation may account for the positive association between early-pregnancy theobromine and preeclampsia.

Circulating angiogenic factors in gestational proteinuria without hypertension.

OBJECTIVE: Our goal was to determine whether obstetric outcomes and serum angiogenic factors are altered in women with gestational proteinuria without hypertension. STUDY DESIGN: We performed a nested case-control study of 108 women with gestational proteinuria and compared them with 1564 randomly selected women with normotension without proteinuria during pregnancy (control subjects) and with 319 women who experienced preeclampsia. RESULTS: Women with gestational proteinuria had greater body-mass index and higher blood pressure at study enrollment. Adverse obstetric outcomes were infrequent. Levels of free placental growth factor were lower than control levels beginning early in gestation. Compared with gestational-age matched control subjects, free placental growth factor was reduced beginning 6-8 weeks before proteinuria. Although soluble fms-like tyrosine kinase 1 and soluble endoglin concentrations were elevated 1-2 weeks before proteinuria, these elevations were modest and transient. After the onset of proteinuria, angiogenic factor levels generally did not differ significantly from control levels. CONCLUSION: Gestational proteinuria in healthy nulliparous women appears to be a mild variant of preeclampsia.

Circulating soluble endoglin and placental abruption.

OBJECTIVE: Our objective was to investigate whether serum concentrations of a novel anti-angiogenic factor, soluble endoglin (sEng), could predict placental abruption. METHODS: In a nested case-control study of nulliparous pregnancies, we examined levels of sEng in serum collected prospectively from 31 women who later developed placental abruption and from 31 normal controls. All serum specimens were collected before the onset of hypertension or abruption and before labor or delivery. Serum sEng was compared within three gestational age intervals: early- (<20 weeks), mid- (21-32 weeks), and late (>or=33 weeks) pregnancy. RESULTS: There was no significant difference in sEng between abruption cases and controls in early pregnancy. sEng was significantly elevated among abruption cases at 21-32 weeks (10.7 vs 5.9 ng/mL, P < 0.01). Subgroup analyses revealed no differences in sEng concentrations at any gestational age interval between cases with abruption without hypertension and healthy controls. Among women who developed hypertension and placental abruption, sEng was not significantly increased in early pregnancy, but was in mid-pregnancy (19.3 vs 5.5 ng/mL, P = 0.002) and in late pregnancy (15.6 vs 9.5 ng/mL, P = 0.04). CONCLUSIONS: Serum levels of the anti-angiogenic factor sEng are elevated prior to the development of hypertension and placental abruption. These elevations are not apparent until the late second trimester (26-27 weeks, on average), but they persist from this time in gestation onward. sEng may be useful for identifying pregnant women at risk for abruption and hypertension.

A longitudinal study of angiogenic (placental growth factor) and anti-angiogenic (soluble endoglin and soluble vascular endothelial growth factor receptor-1) factors in normal pregnancy and patients destined to develop preeclampsia and deliver a small for gestational age neonate.

INTRODUCTION: Accumulating evidence suggests that an imbalance between pro-angiogenic (i.e., vascular endothelial growth factor (VEGF) and placental growth factor (PlGF)) and anti-angiogenic factors (i.e., soluble VEGF receptor-1 (sVEGFR-1, also referred to as sFlt1)) is involved in the pathophysiology of preeclampsia (PE). Endoglin is a protein that regulates the pro-angiogenic effects of transforming growth factor beta, and its soluble form has recently been implicated in the pathophysiology of PE. The objective of this study was to determine if changes in maternal plasma concentration of these angiogenic and anti-angiogenic factors differ prior to development of disease among patients with normal pregnancies and those destined to develop PE (preterm and term) or to deliver a small for gestational age (SGA) neonate. METHODS: This longitudinal nested case-control study included 144 singleton pregnancies in the following groups: (1) patients with uncomplicated pregnancies who delivered appropriate for gestational age (AGA) neonates (n = 46); (2) patients who delivered an SGA neonate but did not develop PE (n = 56); and (3) patients who developed PE (n = 42). Longitudinal samples were collected at each prenatal visit, scheduled at 4-week intervals from the first or early second trimester until delivery. Plasma concentrations of soluble endoglin (s-Eng), sVEGFR-1, and PlGF were determined by specific and sensitive ELISA. RESULTS: (1) Patients destined to deliver an SGA neonate had higher plasma concentrations of s-Eng throughout gestation than those with normal pregnancies; (2) patients destined to develop preterm PE and term PE had significantly higher concentrations of s-Eng than those with normal pregnancies at 23 and 30 weeks, respectively (for preterm PE: p < 0.036 and for term PE: p = 0.002); (3) patients destined to develop PE (term or preterm) and those who delivered an SGA neonate had lower plasma concentrations of PlGF than those with a normal pregnancy throughout gestation, and the maternal plasma concentration of this analyte became detectable later among patients with pregnancy complications, compared to normal pregnant women; (4) there were no significant differences in the plasma concentrations of sVEGFR-1 between patients destined to deliver an SGA neonate and those with normal pregnancies; (5) patients destined to develop preterm and term PE had a significantly higher plasma concentration of sVEGFR-1 at 26 and 29 weeks of gestation than controls (p = 0.009 and p = 0.0199, respectively); and (6) there was no significant difference in the increment of sVEGFR-1 between control patients and those who delivered an SGA neonate (p = 0.147 at 25 weeks and p = 0.8285 at 40 weeks). CONCLUSIONS: (1) Changes in the maternal plasma concentration of s-Eng, sVEGFR-1, and PlGF precede the clinical presentation of PE, but only changes in s-Eng and PlGF precede the delivery of an SGA neonate; and (2) differences in the profile of angiogenic and anti-angiogenic response to intrauterine insults may determine whether a patient will deliver an SGA neonate, develop PE, or both.

Neonatal outcomes in pregnancies with preeclampsia or gestational hypertension and in normotensive pregnancies that delivered at 35, 36, or 37 weeks of gestation.

OBJECTIVE: The purpose of this study was to compare neonatal outcomes of pregnancies with preeclampsia or gestational hypertension with those of normotensive pregnancies that delivered at 35, 36, or 37 weeks of gestation separately. STUDY DESIGN: Secondary analysis of neonatal outcomes by week of delivery between 35 and 37 weeks 6 days of gestation to 4293 nulliparous women who were enrolled in a multicenter National Institute for Child Health and Human Development study. Outcomes included the percentage of neonatal intensive care unit admission, duration of neonatal hospitalization, and neonatal complications. RESULTS: As compared with normotensive pregnancies, hypertensive pregnancies that delivered at 35 and 36 weeks of gestation had higher rates of small for gestational age births (17.9% vs 1.7% [P < .05] and 33.3% vs 12.2% [P < .01], respectively) and neonatal intensive care unit admission (57.1% vs 34.5% [P < .05] and 33.3% vs 10.7% [P < .001]). The rate of neonatal intensive care unit admission (25.6% vs 8.7%; P < .001) and duration of neonatal stay (3.9 vs 2.0 days; P < .001) were greater in hypertensive pregnancies that delivered at 37 weeks of gestation. These differences were observed largely in women whose condition required labor induction, regardless of the severity of the hypertensive disease. CONCLUSION: Pregnancies with preeclampsia or gestational hypertension that delivered between 35 and 37 weeks of gestation had higher rates of neonatal intensive care unit admission, small for gestational age, and longer neonatal stay than normotensive pregnancies, regardless of the severity of the hypertensive disease.

Misclassification of maternal smoking status and its effects on an epidemiologic study of pregnancy outcomes.

Reliance on self-reported smoking status among pregnant women can result in exposure misclassification. We used data from the Calcium for Preeclampsia Prevention trial, a randomized study of nulliparous women conducted from 1992 to 1995, to characterize tobacco exposure misclassification among women who reported at study enrollment that they had quit smoking. Urinary cotinine concentration was used to validate quit status, and factors associated with exposure misclassification and the effects of misclassification on associations between smoking and pregnancy outcomes were evaluated using logistic regression. Of 4,289 women enrolled, 508 were self-reported smokers and 771 were self-reported quitters. Of 737 self-reported quitters with a valid cotinine measurement, 21.6% had evidence of active smoking and were reclassified as smokers. Women who reported having quit smoking during pregnancy were more likely to be reclassified than women who reported quitting before pregnancy (p<.001). Among smokers, factors independently associated with misclassification of smoking status included fewer cigarettes smoked per day and fewer years smoked. After reclassification the odds ratio for a small-for-gestational-age birth among smokers decreased by 14%, and the smoking-related reduction in birth weight decreased by 15%. Effects of misclassification on the association with hypertensive disorders of pregnancy were present but less dramatic. In conclusion, use of self-reported smoking status collected at the time of study enrollment resulted in the introduction of bias into our study of smoking and pregnancy outcomes. The potential for this type of bias should be considered when conducting and interpreting epidemiologic studies of smoking and pregnancy outcomes.

Seasonal variation in serum concentrations of reproductive hormones and urinary excretion of 6-sulfatoxymelatonin in men living north and south of the Arctic Circle: a longitudinal study.

OBJECTIVE: Seasonal variation in photoperiod or temperature may influence human reproductive biology. The present study evaluated whether seasonal changes occurred in the levels of reproductive hormones and the major melatonin metabolite, 6-sulfatoxymelatonin (aMT6s), in populations exposed to extreme variation in photoperiod and temperature. DESIGN: Two separate cohorts of Norwegian men were recruited from the general population in either of two locations: Tromsø (69.5 degrees N, n = 92) or Oslo (60 degrees N, n = 112), located north and south of the Arctic Circle (66.5 degrees N), respectively. MEASUREMENTS: Four blood and 12-h overnight urine samples were obtained on separate occasions over a 12-month period, including during the photoperiod maximum and minimum. Serum concentrations of FSH, LH, testosterone (T), oestradiol (E(2)), SHBG and the urinary excretion of aMT6s were assessed. RESULTS: Statistical analysis using generalized estimating equations indicated that LH levels were lowest during early winter in both locations (both P = 0.01). In Tromsø, free T and E(2) concentrations peaked during early winter (P = 0.02 and 0.003, respectively). In Oslo, free T levels were lowest during early winter (P = 0.06) whereas E(2) levels were lowest during late summer (P < 0.001). Urinary aMT6s concentrations were lowest during early summer in Tromsø and Oslo. Concentrations peaked during early winter in Tromsø (P < 0.001) and during late winter in Oslo (P < 0.001). CONCLUSIONS: LH levels exhibited similar changes in both locations, whereas the patterns of changes of the sex steroid concentrations differed, possibly indicating different underlying mechanisms. Excretion of aMT6s was lowest during early summer in both locations, indicating that the long natural photoperiod was sufficient to cause suppression of melatonin secretion. Whether these changes have any biological significance remains uncertain.

Sequential changes in antiangiogenic factors in early pregnancy and risk of developing preeclampsia.

Concentrations of soluble fms-like tyrosine kinase 1 (sFlt1) and soluble endoglin (sEng) increase in maternal blood with the approach of clinical preeclampsia. Although alterations in these circulating antiangiogenic factors herald the signs and symptoms of preeclampsia, in vitro studies suggest they may also play a role in regulating early placental cytotrophoblast functions. Early pregnancy changes in sFlt1 and sEng may thus identify women destined to develop preeclampsia. We performed a nested case-control study of 39 women who developed preeclampsia and 147 contemporaneous normotensive controls each with serum collected in the first (11 to 13 weeks of gestation) and second (17 to 20 weeks) trimesters. Whereas levels of sFlt1 and sEng at 11 to 13 weeks were similar between cases and controls (sFlt1: 3.5+/-0.3 ng/mL versus 3.0+/-0.1, P=0.14; sEng 6.9+/-0.3 ng/mL versus 6.6+/-0.2, P=0.37, respectively), at 17 to 20 weeks both were elevated in the women destined to develop preeclampsia (sFlt1: 4.1+/-0.5 ng/mL versus 3.1+/-0.1, P<0.05; sEng, 6.4+/-0.4 ng/mL versus 5.2+/-0.1, P<0.01). Women who developed preterm (<37 weeks) preeclampsia demonstrated even greater sequential changes: difference [delta{d}] between second and first trimester levels: dsFlt1, 0.63+/-0.91 ng/mL in preterm PE versus 0.05+/-0.15 in controls; dsEng, 0.73+/-0.77 ng/mL versus -1.32+/-0.18, P<0.01. Similar findings were noted in a cross-sectional analysis of specimens collected from the Calcium for Preeclampsia Prevention Study. In conclusion, sequential changes in antiangiogenic factors during early pregnancy may be useful for predicting preterm preeclampsia.