Thrombophilia and fetal growth restriction.
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Blood Coagulation↗
Biomedical subjects
L L Peeters
Publications and source records attributed to L L Peeters.
Non-pregnant circulatory volume status predicts subsequent pregnancy outcome in normotensive thrombophilic formerly preeclamptic women.
BACKGROUND: Preeclampsia seems to be superimposed upon a preexisting hemodynamic, hemostatic, autoimmune or metabolic disorder. We tested the hypothesis that in normotensive thrombophilic formerly preeclamptic subjects, the non-pregnant circulatory volume status predicts the development of subsequent hypertensive pregnancy and/or fetal growth restriction. METHODS: In 250 non-diabetic formerly preeclamptic women and 15 normal parous controls, we measured and calculated the following variables at least 5 months postpartum at day 5 (+/-2) of the menstrual cycle: mean arterial pressure, body mass index, plasma volume and the clotting function. In the subsequent pregnancy we determined, birth weight, birth-weight centile and the incidence of preterm birth, fetal growth restriction, pregnancy-induced hypertension, preeclampsia and HELLP-syndrome. We only included in the final analysis normotensive subjects with a thrombophilic phenotype at the time of the pre-pregnant screening, who had a subsequent singleton pregnancy, ongoing beyond 16 weeks gestation within 1 year after pre-pregnant evaluation. As a consequence, 23 formerly preeclamptic women and 12 controls were eligible for final analysis. The thrombophilic formerly preeclamptic participants received aspirin in combination with low-molecular-weight heparin throughout pregnancy. If thrombophilia was diagnosed on the basis of hyperhomocysteinemia, the treatment consisted of aspirin, pyridoxine and folic acid, instead. RESULTS: Among 250 formerly preeclamptic 131/250 (52%) had a normotensive thrombophilic phenotype. Only 23 (18%) of these 131 participants had an ongoing pregnancy within 1 year. They were allocated to subgroup THROMB. None of the controls had hypertension or thrombophilia. In contrast, 12/15 (80%) controls had an ongoing pregnancy within a year. The observations in the THROMB subgroup were compared with those in the control group. None of the baseline demographic and blood pressure variables differed between THROMB and controls. With respect to pregnancy outcome, the incidence of the following pregnancy complications were observed in THROMB subjects: preterm birth: 9%, pregnancy-induced hypertension: 44%, preeclampsia: 13%, HELLP-syndrome: 13%, and fetal growth restriction: 30%. A low non-pregnant plasma volume was found to predispose for hypertensive complications in a subsequent pregnancy. CONCLUSION: Pre-pregnant plasma volume in normotensive thrombophilic formerly preeclamptic women have predictive value with respect to hypertensive complications in the subsequent pregnancy.
Aspirin↗
Latent hemodynamic abnormalities in symptom-free women with a history of preeclampsia.
OBJECTIVE: Most women with a pregnancy complicated by preeclampsia have either hypertension or a disorder with a thrombophilic phenotype or both of these. In this study we evaluated whether hemodynamic variables and volume homeostasis in a subgroup of normotensive women with a history of preeclampsia with normal clotting function (defined as the symptom-free subgroup) were comparable with those in a healthy parous control group. STUDY DESIGN: In a group of 58 subjects with a history of preeclampsia and a group of 11 healthy parous control subjects we measured the following variables > or = 5 months post partum at day 5 +/- 2 of the menstrual cycle: body weight and length, mean arterial pressure, heart rate, cardiac output, plasma volume, glomerular filtration rate, effective renal plasma flow, and plasma concentrations of volume regulatory hormones, clotting factors, antiphospholipid antibodies, and homocysteine before and after a methionine load. From the measured data we calculated body mass index, body surface area, cardiac index, left ventricular work, total peripheral and renal vascular resistances, effective renal blood flow, and renal filtration fraction. RESULTS: Among women with a history of preeclampsia 26 were normotensive with thrombophilia (45%), 14 had hypertension (24%), and 18 were normotensive without thrombophilia (31%). These last symptom-free subjects with a history of preeclampsia were more obese than were control subjects. They also had higher cardiac output and left ventricular work and a lower plasma volume than the healthy parous control subjects. Thus they resemble the second subgroup of subjects (subjects with hypertension and a history of preeclampsia) rather than the control subjects. The hemodynamic and renal functions in the subgroup of subjects with a history of preeclampsia with normotension and thrombophilia were similar to those in healthy parous control subjects. CONCLUSION: On the basis of this study we conclude that hemodynamic parameters and volume homeostasis in the symptom-free subgroup of women with a history of preeclampsia are different from those in healthy parous control subjects. Hemodynamic parameters and volume homeostasis in this subgroup resemble those of women with hypertension and a history of preeclampsia. We therefore propose the classification of these symptom-free subjects with a history of preeclampsia as having "latent" hypertension.
Adult↗
Aneurysm of the umbilical vein: case report and review of literature.
We report a case of aneurysm of the umbilical vein, causing fetal death at 41 weeks gestation. We conclude that these aneurysms are a complication of congenital thinning of the vessel wall and want to emphasize that in stillbirths the cause of death may only be revealed by careful placental examination, including the umbilical cord.
Adult↗
Changes in hemodynamic parameters and volume homeostasis with the menstrual cycle among women with a history of preeclampsia.
OBJECTIVE: Among women with a history of preeclampsia the prevalence of hemodynamic and clotting disorders is elevated. In this study we tested the hypothesis that the normal cyclic variation in hemodynamic and renal function parameters with the menstrual cycle that is seen among healthy women would be preserved in women with a history of preeclampsia irrespective of whether they had an underlying hemodynamic or clotting disorder. STUDY DESIGN: We compared the hemodynamic and volume cyclic variations during the menstrual cycle among women with a history of preeclampsia (n = 39) with those among healthy parous control women (control group, n = 10). The participants with a history of preeclampsia were subdivided into groups of women with hypertension with or without thrombophilia (hypertension group, n = 10), women with a normotension and a thrombophilic disorder (thrombophilia group, n = 17), and women without either of these abnormalities (symptom-free group, n = 12). We measured > or =5 months post partum, once during the follicular phase of the menstrual cycle (day 5 +/- 2) and once during the luteal phase (day 22 +/- 2), the following variables: body weight and length, mean arterial pressure, heart rate, cardiac output, plasma volume, glomerular filtration rate, effective renal plasma flow, and concentrations of renal volume homeostatic hormones, reproductive hormones, and catecholamines. From the measured data we calculated body mass index, cardiac index, left ventricular work, total peripheral and renal vascular resistances, effective renal blood flow, and renal filtration fraction. RESULTS: The hypertension group differed from the control group in having higher baseline (follicular phase) values for cardiac output, cardiac output, left ventricular work, renal vascular resistance, and atrial natriuretic peptide and norepinephrine levels. The symptom-free group differed from the control group in having a lower baseline plasma volume and higher baseline cardiac output and left ventricular work values. Women in the thrombophilia group were comparable to those in the control group with respect to baseline hemodynamic and renal function variables except for a higher renal vascular work value. In the control group heart rate, plasma volume, effective renal plasma volume, effective renal blood flow, and concentrations of renin-angiotensin-aldosterone system hormones and norepinephrine were increased during the luteal phase with respect to values during the follicular phase, whereas the renal vascular resistance and atrial natriuretic peptide values were decreased. In the three subgroups of women with a history of preeclampsia this cyclic pattern with the menstrual cycle was preserved for most of these parameters. CONCLUSION: Although baseline hemodynamic and volume status among women with a history of preeclampsia differed from that among healthy parous control subjects, the cyclic variation with the menstrual cycle was largely preserved.
Atrial Natriuretic Factor↗
The effect of pregnancy on the compliance of large arteries and veins in healthy parous control subjects and women with a history of preeclampsia.
OBJECTIVE: Early pregnancy is characterized by a fall in total peripheral vascular resistance. In this study we tested the hypothesis that this phenomenon is accompanied by rising compliances of the large arteries and veins. STUDY DESIGN: In 42 women with a history of preeclampsia and 10 healthy parous control subjects we measured the following variables in the midfollicular phase and the midluteal phase during the menstrual cycle and again at 5 and at 7 weeks of amenorrhea: cardiac output, mean arterial pressure, carotid and femoral artery compliances, and venous compliance. The total peripheral vascular resistance was determined as the ratio of mean arterial pressure and cardiac output. After screening for thrombophilia and hypertension, women with a history of preeclampsia were divided into subgroups with hypertension, thrombophilic disorders, and no underlying abnormalities. RESULTS: In parallel with the fall in total peripheral vascular resistance during early pregnancy, femoral artery compliance and venous compliance increased in the control group. Except for venous compliance, these changes were also observed in the women with thrombophilia and a history of preeclampsia. In the subgroups of the women with a history of preeclampsia with hypertension and with no underlying disorder both arterial and venous compliance failed to increase despite a drop in total peripheral vascular resistance. CONCLUSION: These data support the concept that during normal pregnancy the fall in total peripheral vascular resistance is paralleled by improved macrovascular compliance. The latter adaptive change did not occur in women with a history of preeclampsia with hypertension or without an underlying disorder.
Arteries↗
Cardiac output increases independently of basal metabolic rate in early human pregnancy.
Early pregnancy is characterized by the institution of a high-flow low-resistance circulation. In this study, we tested the hypothesis that these hemodynamic changes develop independently of changes in basal metabolic rate. In 12 healthy women, we determined and calculated once during the follicular phase (day 5 +/- 2) and at 6, 8, 10, and 12 wk of pregnancy the following variables: body weight and length, body mass index, fat-free mass (FFM), mean arterial pressure (MAP), heart rate (HR), stroke volume, cardiac output (CO), total peripheral vascular resistance (TPVR), resting energy expenditure (REE), FFM REE (REE(FFM)), and respiratory quotient (RQ). At 6 wk of gestational age, HR and CO had increased, whereas MAP and TPVR had decreased. These changes persisted throughout the study period. Meanwhile, REE, REE(FFM), RQ, FFM, and body weight did not change consistently. The changes with pregnancy in hemodynamics did not correlate with those in basal metabolic rate. In early pregnancy, the institution of a high-flow low-resistance circulation develops without a concomitant rise in basal metabolic rate. These findings support the concept that the hemodynamic changes in early pregnancy develop independently of concomitant changes in basal metabolic rate.
Adult↗
[Sodium restriction during pregnancy: an outdated advice].
Even in an early phase of pregnancy marked haemodynamic changes occur, including a fall in vascular resistance and blood pressure and a rise in cardiac output. To compensate for the increased intravascular capacity the kidney retains more sodium and water. Apparently, the set point of sodium homeostasis shifts to a higher level at the expense of an expansion of extracellular volume. Studies during the normal menstrual cycle have shown that these changes, albeit smaller, also occur during the luteal phase. These fluctuations with the menstrual cycle are less apparent if salt intake is low, suggesting that a high salt intake is needed to facilitate the process of sodium retention. In pregnancies complicated by hypertension and/or pre-eclampsia body fluid volumes are low with an enhanced tendency to retain sodium after a volume challenge. These data, together with the lack of an apparent benefit of sodium restriction, suggest that the practice of prescribing a low-salt diet to hypertensive pregnant women should be abandoned.
Adult↗
A new method for plasma volume measurements with unlabeled dextran-70 instead of 125I-labeled albumin as an indicator.
A method has been developed to determine plasma volume with dextran-70 without the use of a fluorescent label. The results obtained are compared to those found using the 125I-labeled albumin method, which is taken as the gold standard. The CV of the method is about 5%, compared to 3% with the gold standard. It is shown to be of use for the determination of an increase in plasma volume during pregnancy.
Dextrans↗
Persistent abnormalities in plasma volume and renal hemodynamics in patients with a history of preeclampsia.
OBJECTIVE: The objective was to test the hypothesis that women with a recent history of preeclampsia have abnormalities in renal hemodynamics and volume status. STUDY DESIGN: We studied a group of 26 primiparous women with history of preeclampsia and a group of 12 parous women with a history of uneventful pregnancies (control group). At least 4 months post partum we compared the following variables between these groups: effective renal plasma flow, glomerular filtration rate, plasma volume, plasma concentration of active renin, plasma concentration of angiotensin II, plasma concentration of aldosterone, and plasma concentration of atrial natriuretic peptide. RESULTS: Both plasma volume and plasma concentration of atrial natriuretic peptide were lower in the formerly preeclamptic group. Compared with the control subjects, the formerly preeclamptic group also had a lower effective renal plasma flow, a higher filtration fraction, and a higher renal vascular resistance. Intergroup differences in plasma concentration of active renin, plasma concentration of angiotensin II and plasma concentration of aldosterone were small and inconsistent. CONCLUSIONS: Women with history of preeclampsia are relatively hypovolemic and tend to have lower effective renal plasma flow and higher renal vascular resistance and filtration fraction than do control subjects. These findings support the hypothesis that otherwise healthy women with a history of preeclampsia show abnormalities in their volume status and renal hemodynamics, irrespective of their blood pressure.
Adult↗
The extent of trophoblast invasion in the preplacental vasculature of the guinea-pig.
Pregnancy-induced structural changes in spiral arteries seem to be a prerequisite for successful fetal outcome in humans. It is unknown whether these changes also occur in other preplacental vessels (radial and arcuate arteries) in normal pregnancies. Since the radial and arcuate arteries need to dilate in order to accommodate the increase in placental blood flow during pregnancy, it is expected that they are also invaded by trophoblast and respond with structural changes. The objective of the present study was to evaluate the extent of trophoblast invasion in the guinea-pig preplacental vasculature and its effect on the vascular structure of mesometrial, myometrial and arcade arteries. Under general anaesthesia the vascular system of non- (n = 4), mid- (n = 4) and late- (n = 8) pregnant guinea-pigs was fixed by immersion or perfusion. Cross-sections of immersion-fixed mesometrial and arcade arteries were stained with toluidine blue. Cross-sections of perfusion-fixed mesometrial, myometrial and arcade arteries were stained with haematoxylin-eosin, Elastica van Gieson staining and antibodies against alpha-smooth-muscle-actin (ASMA), cytokeratin and factor VIII, to detect vascular smooth muscle, trophoblastic, and endothelial cells, respectively. In addition, the external and internal vascular circumference of sections from perfusion-fixed tissue was determined. All cross-sections were evaluated by light microscopy. In the course of pregnancy, progressive endothelial swelling, disappearance of the elastic lamina interna and disarrangement of the tunica media were observed in the myometrial and throughout the mesometrial arteries up to the junction with the arcade arteries. These changes coincided the migration of keratin-positive staining giant cells. It is concluded that in normal guinea-pig pregnancy, structural changes occur in the entire mesometrial artery and at least a part of the myometrial artery, although such changes were not seen in the arcade artery.
Actins↗
Pathogenesis of preeclampsia: a comprehensive model.
The objective of this review was to provide a comprehensive and practical concept on the pathogenesis of preeclampsia on the basis of the currently available scientific evidence. A MEDLINE search was performed of English-language articles published between 1966 and 1997, supplemented with references cited in relevant research articles. Using our data sources, we developed a scheme describing the sequence of events between implantation and the time of manifest clinical disease characterized by generalized endothelial cell dysfunction. A yet unidentified toxic circulating factor released by the ischemic placenta, is held responsible for the impaired endothelial cell function. Particularly, epidemiological studies point to a concept in which immune maladaptation to the fetal allograft plays a key role in causing defective placentation leading to placental ischaemia. The incidence of preeclampsia in sisters and daughters of women who had had preeclampsia is raised. Disease states with vascular involvement, like chronic hypertension and diabetes mellites, are associated with an increased risk for preeclampsia. Recently subclinical abnormalities in hemostasis, metabolism and volume homeostasis have been described in patients with a history of preeclampsia. Placental ischemia secondary to defective placentation, a prerequisite for the development of preeclampsia, has a multifactorial origin consisting of three major components: immune maladaptation, genetic predisposition, and vascular mediated factors. Probably, a summation of these factors will determine whether a pregnant woman is to develop the syndrome. The recently described subclinical abnormalities in hemostasis, metabolism, and vascular function in patients with a history of preeclampsia might give the clinician the opportunity to reduce the recurrence risk by pharmacotherapeutic intervention.
Female↗
Mechanism of volume adaptation in the awake early pregnant rat.
The objective of the present study was to determine whether the increase in plasma volume (PV) during pregnancy is established by fluid retention or by a shift within the extracellular fluid volume (ECFV) from the interstitium toward the intravascular compartment. To this end, we simultaneously, measured total body water, (TBW), ECFV, and PV together with the hematocrit (Hct) and plasma osmolality 4, 8, and 12 days postsurgery in chronically instrumented pregnant (P) and nonpregnant (NP) rats. The P rats were instrumented with a catheter in the femoral artery on day 1 postconception. In the NP group, neither TBW nor ECFV and PV had changed consistently on days 8 and 12 postsurgery relative to day 4. In contrast, in the P animals, TBW, ECFV, and PV had increased by 16, 24, and 20%, respectively, by day 12 relative to day 4. To evaluate whether PV had increased in concert with an overall rise in TBW or as a result of a fluid shift at the cost of the interstitial fluid volume, we calculated the relative size of each fluid compartment on three consecutive measurement sessions. In the NP group, TBW, presented as percentage of maternal weight (%MW) as well as ECFV (%TBW) and PV (%ECFV) had not changed consistently throughout the measurement period. In the P animals, TBW (%MW) was slightly higher on day 12 compared with day 4, but ECFV (%TBW) and PV (%ECFV) had not changed significantly. Finally, in the NP group, Hct had not changed, whereas, in the P animals, Hct was 10% lower on days 8 and 12 compared with day 4. Plasma osmolality did not change consistently in either group during the course of the experimental period. The gradual synchronous increase in all fluid compartments, without consistent change in their relative distribution, suggests that, in normal rat pregnancy, PV expansion is primarily achieved by fluid retention rather than by a redistribution of the ECFV.
Adaptation, Biological↗
[The pathogenesis of preeclampsia].
The central factor in the pathogenesis of preeclampsia appears to be placental ischaemia which is supposed to be caused by an initial defective placentation. The impaired placental function leads to generalized endothelial cell dysfunction, which in its turn gives rise to hypertension, proteinuria, oedema, thrombocytopenia and hypoperfusion, especially of liver and kidneys. The link between placental ischaemia and endothelial dysfunction could consist of a toxic circulating 'factor X' and the multifactorial origin of the defective placentation. Impaired development of immunological tolerance may lead to an activated immune system during trophoblast invasion which then causes defective placentation. Genetic predisposition and maternal vascular pathology could be modulating factors in this process. The recent finding of latent abnormalities in haemostasis, in metabolism (giving rise to thrombophilia), and in volume homeostasis in patients with a history of preeclampsia in suggestive of an important role of these vascular mediators in the pathogenesis of preeclampsia.
Endothelium↗
Hemodynamic changes in pseudopregnancy in chronically instrumented conscious rats.
It is unclear whether the trophoblast is needed for the normal early-pregnancy hemodynamic adaptation. In this study we tested the hypothesis that the presence of trophoblast is not essential for the initial hemodynamic adaptation in pregnancy. To this end, we measured systemic hemodynamics in conscious pseudopregnant rats and compared the results with those obtained in a concomitantly studied control group of virgin rats as well as with a previously studied group of pregnant rats. The rats were studied daily from day 4 postmating until day 10 and on days 12, 14, 18, and 20. In pseudopregnant rats, cardiac output (CO) increased from day 5 onward, to 14 +/- 3% above the initial value by day 8. This rise in CO was entirely accomplished by a rise in stroke volume (21 +/- 4% by day 8). Mean arterial pressure did not change appreciably. Therefore, total peripheral resistance also decreased by 21 +/- 4% by day 8. Meanwhile, peak flow, aortic flow acceleration, and stroke work, indicators of myocardial performance, had increased, and the hematocrit had decreased (15 +/- 1% by day 8). Between day 10 and day 20 the hemodynamic parameters gradually returned to baseline. We conclude that systemic hemodynamic changes do take place in pseudopregnancy. They consist of a rise in CO by a rise in stroke volume, an increase in myocardial performance, and hemodilution. The observed changes closely resemble those in early normal pregnancy. Therefore, we accept our hypothesis that trophoblast is not essential for the initial hemodynamic changes in rat pregnancy.
Animals↗
Aortic distensibility and compliance in conscious pregnant rats.
In pregnancy, complex hormonal and hemodynamic changes develop. In this study, we tested the hypothesis that these pregnancy-associated changes are accompanied by an alteration of the compliance of central conduit vessels. To this end, we determined in awake, restrained pregnant rats the distensibility (DC) and compliance (CC) coefficients of the descending thoracic aorta. End diastolic aortic diameter (d) and changes in aortic diameter during the cardiac cycle (delta d) were measured noninvasively by ultrasound, simultaneously with diastolic aortic blood pressure (Pdia) and pulse pressure (delta P) through a chronically implanted catheter. From these parameters, DC and CC (expressed as the relative and the absolute increase, respectively, in lumen cross-sectional area for a given increase in P) were calculated. Nine rats were studied before pregnancy and, on days 4, 8, 10, and 18 of pregnancy, were matched for age and days postsurgery with eight nonpregnant rats. On day 20, the animals were killed and the thoracic aorta was isolated for morphometric analysis. In the pregnant group, Pdia decreased from 109 +/- 5 mmHg on day 4 to 98 +/- 9 mmHg on day 18 (means +/- SD), whereas d did not change. delta d increased from 242 +/- 20 microm on day 4 to 271 +/- 29 microm on day 18. delta P did not change. Both DC and CC increased in early pregnancy to a plateau reached by day 10. The increase in DC and CC preceded the fall in Pdia. On day 20, neither cross-sectional area nor thickness of the aortic media had changed significantly, when compared with the nonpregnant group. In the nonpregnant group, none of the variables changed consistently during the study period. On the basis of these results, we conclude that CC of the thoracic aorta increases in early pregnancy. We speculate that the increased aortic CC and DC and the decreased total peripheral resistance develop in early pregnancy in response to the increase in stroke volume, thus preventing a concomitant rise in arterial wall stress.
Animals↗
Blood pressure and heart rate variability in early pregnancy in rats.
Changes in the autonomic control of the circulation may contribute to the maternal hemodynamic adaptation to early pregnancy. To evaluate this, we studied mean arterial pressure (MAP) and heart rate (HR) in chronically instrumented, conscious rats in early (days 4, 6, 8, and 10) and late (day 18) pregnancy (n = 8) and in nonpregnant rats (n = 9). MAP and HR were recorded on a beat-to-beat basis and analyzed by spectral analysis. Spectral density power was calculated in low- (0.047-0.305 Hz), mid- (0.305-0.598 Hz), and high-frequency (0.598-1.494 Hz) bands, which contain oscillations that are among others related to myogenic-, sympathetic/vagal-, and vagal/respiration-related influences, respectively. In addition, baroreceptor reflex sensitivity was determined from spontaneous variations in MAP and HR by a sequential time series method and by calculating the transfer gain between MAP and HR in the midfrequency band. Mean values of HR and MAP did not differ between the two groups on day 4. In the pregnant group, MAP fell gradually over days, whereas HR had significantly increased only on day 18. Overall variability in MAP and HR (expressed as coefficients of variation) did not change during pregnancy. Baroreceptor reflex sensitivity did not differ between the groups and did not change with advancing pregnancy. Spontaneous oscillations of MAP and HR at low, mid, and high frequencies were not different between pregnant and nonpregnant rats on days 4 to 10. On day 18, spectral density power of MAP, but not of HR, in the high-frequency band had significantly increased in pregnant rats only, most likely reflecting the increased impact of breathing on MAP fluctuations. We conclude that, with the methods employed, we could not discern any changes in baroreflex sensitivity and MAP and HR variability in pregnancy. This would imply that changes in autonomic activity do not contribute appreciably to the hemodynamic adaptations in early rat pregnancy.
Animals↗
Peripheral haemodynamics and renal function in relation to the menstrual cycle.
1. The objective of this study was to investigate whether the luteal phase of the menstrual cycle differs from the follicular phase by the development of a state of general vascular relaxation. 2. Once in the follicular and once in the luteal phase of the menstrual cycle, we measured by non-invasive techniques: arterial blood pressure (by finger blood pressure measurements), vascular tone (by pulse-wave velocity and plethysmography), blood flow to skin (by laser-Doppler), blood flow to forearm (by plethysmography) and blood flow to kidneys (by para-aminohippurate clearance), and the glomerular filtration rate (by inulin clearance). The data points obtained in the luteal phase were compared with those in the follicular phase by non-parametric tests. 3. Arterial blood pressure, vascular tone and the blood flows to the forearm and kidneys were comparable in the two phases of the menstrual cycle. In contrast, the blood flow to the skin was consistently lower, and the glomerular filtration rate higher in the luteal phase of the menstrual cycle. 4. The results of the present study do not support our hypothesis of a general vascular relaxation in the luteal phase of the menstrual cycle. The lower skin flow in the luteal phase may be an adaptation needed to ensure the higher core temperature of 0.3-0.5 degree C in the luteal phase. The higher glomerular filtration rate was in most case paralleled by a higher renal blood flow in the luteal phase. This suggests that the higher glomerular filtration rate is secondary to a selective vasorelaxation of the afferent renal arterioles.
Adult↗