Increase In Uterine Volume Research Articles

Progression of adenomyosis: Rate and associated factors.

To evaluate the rate of disease progression and the factors associated with such progression in patients with an ultrasound diagnosis of adenomyosis. This was a single center, prospective, observational, cohort study performed at a tertiary referral center. Patients who obtained an ultrasound diagnosis of adenomyosis from May 2022 to August 2022 were recruited. Demographic, clinical and ultrasound data were recorded at the first visit (T0) and after 12 months (T1) for enrolled patients and compared between T0 and T1. The study population was divided in two groups according to progression (increase in uterine volume >20%) or stability/regression (decrease or increase in uterine volume ≤20%) of adenomyosis at T1. Primary study outcome was the rate of adenomyosis progression, while secondary study outcome was the association of adenomyosis progression with demographic and clinical factors. Post hoc subgroups analyses for primary and secondary study outcomes were performed based on hormonal therapy (untreated and treated). A total of 221 patients were enrolled in the study, with no significant difference in terms of baseline data among the two study groups and no patients were lost to follow-up. The overall rate of adenomyosis progression was 21.3% (47/221 patients). The rate was 30.77% in hormonally untreated women, and 18.34% in hormonally treated women. Progression was associated with the presence of focal adenomyosis of the outer myometrium (P = 0.037), moderate to severe dysmenorrhea (P = 0.001), chronic pelvic pain (P = 0.05), dyschezia (P = 0.05), and worsening of chronic pelvic pain (P = 0.04) at T1. Adenomyosis showed a rate of disease progression of 21.3% at the 12-month follow-up (30.77% in hormonally untreated women, and 18.34% in hormonally treated women). The presence and/or worsening of painful symptoms, such as severe dysmenorrhea, dyschezia and chronic pelvic pain, as well as the presence focal adenomyosis of the outer myometrium, might help identify patients at higher risk of disease progression and tailor their follow-up.

Long-term evaluation of uterine fibroid embolisation using MRI perfusion parameters and patient questionnaires: preliminary results

BackgroundUterine fibroid embolisation (UFE) is an established treatment method for symptomatic uterine myomas. This study evaluates the efficacy of UFE using objective magnetic resonance imaging (MRI) data for size and perfusion analysis as well as patient questionnaires assessing fibroid-related symptoms.MethodPatients underwent MR-Angiography before UFE and 4 days, 6 and 12 months after the procedure. The images were evaluated using dedicated software. Patient questionnaires were completed before UFE and at 12 months follow-up, focussing on the embolization procedure and symptoms associated with uterine fibroids. Statistical analysis of the questionnaires was performed using paired sample t-test and Wilcoxon signed rank test, while Kruskal–Wallis test and Friedman test were applied for MRI-analysis.ResultsEleven women were included. There was a significant reduction in fibroid-related symptoms. The volume reduction after 12 months was significant in both, uterus and myomas, after an initial increase in uterine volume at the first post-interventional MRI. The perfusion analysis showed that blood flow to the fibroids could be significantly reduced up to 12 months after UFE while uterine tissue was not affected.ConclusionThis study shows that uterine fibroid embolisation induces a significant long-term decrease in myoma size and perfusion while healthy uterine tissue remains unaffected. Fibroid-related symptoms are reduced for the sake of improved quality of life.

Uterine involvement by endometriosis: Sonographic features from elusive findings to apparent adenomyosis

ObjectiveThe primary aim of this study is to investigate whether there are any minor sonographic uterine findings, not typical for adenomyosis, in endometriosis patients. The secondary objective is to determine the prevalence of sonographic features of adenomyosis in an infertile population with endometriosis. Study designThe investigation was of 291 infertile women with endometriosis, either manifesting endometrioma (OMA) or diagnosed through laparoscopy, who were investigated for two‐dimensional transvaginal sonographic (2D-TVS) features of adenomyosis. These patients were grouped as either having endometriosis with adenomyosis (EwA,n = 121) or without adenomyosis (EwoA, n = 170). Additionally, patients without both endometriosis and 2D-TVS features of adenomyosis constituted the control group (n = 170). ResultsAt least one 2D-TVS feature of adenomyosis was detected in 41.6 % (n = 121) of women with endometriosis. Asymmetrical myometrial thickening of uterine walls (57.9 %), hyperechogenic islands (47.1 %), and fan-shaped shadowing (46.9 %) were relatively more prevalent 2D-TVS findings among EwA patients. Multiple OMA (p = 0.038), OMA ≥ 4 cm (p = 0.034), and total OMA volumes were found to be higher (p = 0.004) in the EwA group. Additionally, uterine volumes were found to be 96.7 cm3, 73.0 cm3, and 64.2 cm3 in the EwA, EwoA, and control groups, respectively (EwA vs EwoA, p < 0.001; EwoA vs control, p <0.001). Multivariate linear regression analysis revealed that the presence of endometriosis was independently associated with an increase in uterine volume (β = 0.243, p < 0.001). ConclusionA stepwise and statistically significant volume increase from the control group to the EwoA and then to the EwA group may reflect a spectrum of uterine involvement in endometriosis. This might indicate that many uterine endometriosis cases are still hidden from view, possibly demonstrating an "iceberg phenomenon".

Effect of Dosage of 17ß-Estradiol on Uterine Growth in Turner Syndrome-A Randomized Controlled Clinical Pilot Trial.

Most Turner syndrome (TS) girls need exogenous estrogen treatment to induce puberty and normal uterine growth. After puberty, the optimal estrogen treatment protocol has not been determined. To compare 2 doses of oral 17ß-estradiol on uterine size. A double-blind, 5-year randomized controlled clinical trial. Ambulatory care. Twenty young TS women (19.2 ± 2.5 years, range 16.0-24.9) participated. Sixteen patients completed the study. No patients withdrew due to adverse effects. The lower dose (LD) group took 2 mg 17ß-estradiol/d orally and placebo. The higher dose (HD) group took 4 mg 17ß-estradiol/d orally. Uterine volume evaluated by transabdominal ultrasound yearly. Uterine size increased significantly more in the HD group compared with the LD group (P = 0.038), with a gain in uterine volume within the first 3 years of treatment of 19.6 mL (95% confidence interval [CI] = 4.0-19.0) in the HD group compared with 11.5 mL (95% CI = 11.2-27.9) in the LD group. The difference in 3-year gain was 8.1 mL (95% CI = 0.7-15.9). At the last visit, there were no significant differences in uterine volume between the groups. HD oral 17ß-estradiol induces a steeper increase in uterine volume within the first years of treatment compared with the LD. However, the uterine growth potential seems to be the same in most young TS women making the duration of treatment equally significant as estrogen dose, although a few TS women did not experience sufficient uterine growth on 2 mg of estradiol. NCT00134745Abbreviations: BMI, body mass index; BSA, body surface area; DHEAS, dihydroepiandrosteronesulfate; HD, higher dose; HRT, hormone replacement therapy; LD, lower dose; TS, Turner syndrome; US, ultrasound.

Involution of uterus in postpartum period in ultrasound examination

Retrospective analysis of 558 women in postpartum period is presented. In all cases delivery was urgent, one live fetus; vaginal birth happened at 454 (81.4%) patients and by Caesarean section — 104 (18.6%). Ultrasound examination was performed by one doctor, using transabdominal access. The value for assessment of a current of postpartum period has a condition of a cavity of the uterus which decreases on thickness and the volume. Advancement of uterine cavity contraction compared with myometrium shows the ratio of cavity volume to uterine volume, which decreases from 8.0% on day 3 to 4.7% on the 5th day. In a cases of hematometra, no significant increase in uterine volume was obtained.

Phthalates exposure and uterine fibroid burden among women undergoing surgical treatment for fibroids: a preliminary study

To examine the association between phthalate exposure and two measures of uterine fibroid burden: diameter of largest fibroid and uterine volume. Pilot, cross-sectional study. Academic medical center. Fifty-seven premenopausal women undergoing either hysterectomy or myomectomy for fibroids. None. The diameter of the largest fibroid and uterine dimensions were abstracted from medical records. Spot urine samples were analyzed for 14 phthalate biomarkers using mass spectrometry. We estimated associations between fibroid outcomes and individual phthalate metabolites, sum of di(2-ethylhexyl) phthalate metabolites (∑DEHP), and a weighted sum of anti-androgenic phthalate metabolites (∑AA Phthalates) using linear regression, adjusting for age, race/ethnicity, and body mass index. Fibroid outcomes were also examined dichotomously (divided at the median) using logistic regression. Most women were of black ethnicity, overweight or obese, and college educated. In multivariable models, higher levels of mono-hydroxyisobutyl phthalate, monocarboxyoctyl phthalate, monocarboxynonyl phthalate, mono(2-ethylhexyl) phthalate, mono(2-ethyl-5-hydroxyhexyl phthalate) (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), ∑DEHP, and ∑AA Phthalates were positively associated with uterine volume. Associations were most pronounced for individual DEHP metabolites (MEHHP, MEOHP, MECPP), ∑DEHP, and ∑AA Phthalates. For example, a doubling in ∑DEHP and ∑AA Phthalates was associated with 33.2% (95% confidence interval 6.6-66.5) and 26.8% (95% confidence interval 2.2-57.4) increase in uterine volume, respectively. There were few associations between phthalate biomarkers and fibroid size. Exposure to some phthalate biomarkers was positively associated with uterine volume, which further supports the hypothesis that phthalate exposures may be associated with fibroid outcomes. Additional studies are needed to confirm these relationships.

Efficacy of Hormonal Therapies for Decreasing Uterine Volume in Patients with Adenomyosis.

Study objective:The aim of this study is to evaluate the efficacy of hormonal therapies for inhibiting an increase in uterine volume in patients with adenomyosis.Design:This was retrospective cohort study.Setting:This study was conducted at Nippon Medical School Musashikosugi Hospital.Patients:A total of 28 women diagnosed with adenomyosis using magnetic resonance imaging.Methods:After providing informed consent, patients were treated with gonadotropin-releasing hormone agonist (GnRHa group), a low-dose estrogen and progestin combination (LEP group), or dienogest (DNG group) for ≥16 weeks. Uterine volume was assessed using the formula for an ovoid; uterine volumes before and after 16 weeks of treatment were compared. A <5% increase in uterine volume at 16 weeks was considered to reflect inhibition of uterine volume increase and efficacy of the medication. We compared the efficacy rate among the groups.Results:In the GnRHa group, a significant reduction in uterine volume was noted, from 307.4 ± 230.1 to 177.9 ± 142.1 cm3 (P < 0.001). In the LEP and the DNG groups, there was no significant change (LEP: 226.7 ± 116.6 cm3 pre-treatment and 230.5 ± 128.6 cm3 post-treatment, P = 0.85; DNG: 232.6 ± 117.8 cm3 pre-treatment and 262.1 ± 136.8 cm3 post-treatment, P = 0.37). The number of responders (efficacy rate) in the GnRHa group, LEP group, and DNG group was 25/26 (96.2%), 7/15 (46.7%), and 6/11 (54.5%), respectively. The efficacy rate of GnRHa therapy was significantly higher than that of LEP or DNG therapy (P < 0.001 and P = 0.005, respectively).Conclusion:We conclude that the efficacy of GnRHa in reducing uterine volume should be considered when prescribing hormone therapy for adenomyosis.

Pregnancy impact on uterosacral ligament and pelvic muscles using a 3D numerical and finite element model: preliminary results.

We studied the geometry of and changes in structures that play an important role in stabilizing the pelvic system during pregnancy using a numerical system at different gestational ages and postpartum. We developed a parturient numerical model to assess pelvic structures at different gestational stages (16, 32, and 38weeks) and postpartum (2months and 1year) using magnetic resonance imaging (MRI). Organs, muscles, and ligaments were segmented to generate a 3D model of the pelvis. We studied changes in the length of uterosacral ligaments (USL) and thickness of the puborectal portion of the levator ani muscle (LAM) during and after pregnancy. We used this model to perform finite element (FE) simulation and analyze deformations of these structures under stress from the increase in uterine weight. Analysis reveals an increase in the length of US ligaments at 16, 32, and 38 weeks. Two months after delivery, it decreases without returning to the length at 16 weeks of pregnancy. Similar changes were observed for the puborectal portion of the LAM. Variations observed in these structures are not equivalent to other anatomical structures of pelvic suspension. FE simulation with increased uterus weight does not lead to those findings. This analysis brings new elements and a new focus for discussion relating to changes in pelvic balance of parturient women that are not simply linked to the increase in uterine volume.

Enlarged uterine corpus volume in women with endometriosis: Assessment using three-dimensional reconstruction of pelvic magnetic resonance images.

To assess and compare the uterine volume and endometrium length between women with and without endometriosis, using pelvic magnetic resonance imaging scans. In this case-control study, a total of 75 nulligravid women (aged 20-45 years) with regular menstrual cycles whose uterus were free of any surgically confirmed lesions were enrolled. The endometriosis group underwent surgery for endometrioma (n = 39), and the control group underwent surgery for non-endometrioma ovarian cysts (n = 36). The primary outcome was uterine corpus volume, which was assessed using three-dimensional reconstructions of preoperative pelvic magnetic resonance imaging scans. The mean uterine volume was significantly larger in the endometriosis group than in the control group (mean ± standard deviation, 50.9 ± 14.4 cm3 vs 41.7 ± 14.3 cm3 ; P < 0.01). The longitudinal length and transverse diameter of the corpus and the longitudinal length of the endometrium were also significantly greater in the endometriosis group (all, P < 0.01). An increase in uterine volume and endometrium length was observed in women with endometriosis.

Partial benefit of anastrozole in the long-term treatment of precocious puberty in McCune-Albright syndrome

We report a long-term follow-up on the use of anastrozole in the treatment of peripheral precocious puberty (PP) in McCune-Albright syndrome (MAS). A girl, age 3 years and 9 months, was diagnosed with MAS due to PP, café-au-lait spots, and polyostotic fibrous dysplasia. Serum estradiol was elevated, and gonadotropins were suppressed. Pelvic ultrasound showed an enlarged uterus and a follicle cyst (13 mm) in the left ovary. Bone scintigraphy showed osteogenic lesions on the skull, humerus, tibia, and acetabulum. Bone age was 3 years and 5 months at the chronological age of 3 years. After 36 months of treatment with anastrozole (1 mg/day), there was suppression of breast growth, normalization of growth velocity and serum estradiol, and disappearance of ovarian cysts. However, there was increase in uterine volume, advancement of bone age, and two episodes of vaginal bleeding (18th and 24th months). This report shows the partial benefit of anastrozole in the treatment of peripheral PP of girls with MAS.

Pelvic ultrasound evaluation in patients with Turner syndrome during treatment with growth hormone.

Treatment with growth hormone (GH), alone or in combination with oxandrolone, is used in patients affected by Turner syndrome to improve growth velocity and adult height. Since GH interacts with gonadotropins in the stimulation of the human ovary, the aim of our study was to evaluate the possible effects of GH administration on uterine and ovarian characteristics. We performed pelvic ultrasound assessment in 29 patients with Turner syndrome aged 7.5-16.6 years (19 with 45,X karyotype; 10 with variant karyotypes) before and during treatment with GH alone. Uterine volume and ovarian size and morphology were compared to those of 23 age-matched girls with Turner syndrome not treated with GH. Both patients and controls were divided into prepubertal and pubertal groups. Cross-sectional and longitudinal studies (before and every 6 months during GH treatment for 2 years) were performed. We observed a significantly higher uterine anteroposterior diameter and volume in younger (< or = 11 years) GH-treated Turner syndrome girls than in those who were untreated. Also visualization and heterogeneous echopattern of the ovaries were significantly more frequent in treated than in untreated Turner syndrome patients, particularly before the age of 11 years. The longitudinal study showed a significant increase in uterine volume, more related to treatment than to age. Spontaneous breast development and menarche were found more frequently in GH-treated Turner syndrome girls. Growth hormone therapy can have a co-gonadotropin role in patients with Turner syndrome.

A multicentre randomised trial to compare uterine safety of raloxifene with a continuous combined hormone replacement therapy containing oestradiol and norethisterone acetate

Objective To compare the uterine effects of 60 mg of raloxifene with a continuous combined hormone replacement therapy, a preparation of 2 mg 17β-oestradiol (E 2) and 1 mg norethisterone acetate for a duration of 12 months. Design A randomised, double-blind trial. Setting Multicentre: Europe, Israel, South Africa. Population Asymptomatic postmenopausal women with risk factors for osteoporosis or cardiovascular disease who had an endometrial thickness of less than 5 mm. One thousand and eight women were randomised for the six month core; of these 420 were invited to continue into a six month extension period. Methods Randomisation to either raloxifene or continuous combined hormone replacement therapy. Patients, recruiters and assessors were blinded to the treatment used. Main outcome measures The frequency of vaginal spotting/bleeding as recorded in a diary, endometrial thickness and uterine volume as measured by transvaginal ultrasonography at baseline and after 6 and 12 months. Results After six months of therapy with raloxifene, the rate of women on raloxifene reporting vaginal bleeding and spotting (6.8%) was similar to the rate in the lead-in phase (8.3%) but increased from 7.0% to 55.1% in the continuous combined hormone replacement therapy group. Raloxifene treatment was not associated with a significant change from baseline to endpoint in mean endometrial thickness ( P = 0.11), whereas continuous combined hormone replacement therapy treatment was associated with an increase in this value of mean (SD) of 1.2 (2.2) mm ( P < 0.001). Compared with raloxifene, mean endometrial thickness for women on continuous combined hormone replacement therapy was significantly increased at endpoint [4.6 (2.1) mm vs 3.5 (1.7) mm; change from baseline P < 0.001]. In the raloxifene group, there was a trend towards a decrease from baseline in uterine volume [from 31.4 (20.3) to 30.3 (16.2) mm; P = 0.37]; in the continuous combined hormone replacement therapy group, there was a significant increase in uterine volume [from 31.3 (16.3) to 54.0 (36.1) mm; P < 0.001], and the difference in the effect of both compounds on change in uterine volume at endpoint reached statistical significance ( P < 0.001). Statistically significant differences between the treatment groups were sustained for all parameters during the extension period. Early discontinuation rates, both overall and due to adverse events, were significantly lower ( P < 0.001) in the raloxifene group after 6 and 12 months. Conclusion Compared with continuous combined hormone replacement therapy, 6 and 12 months of raloxifene treatment do not lead to vaginal bleeding/spotting, are not associated with increased endometrial thickness or uterine volume and result in a significantly lower rate of early treatment discontinuations in asymptomatic women receiving treatment to prevent long term postmenopausal health risks.

A multicentre randomised trial to compare uterine safety of raloxifene with a continuous combined hormone replacement therapy containing oestradiol and norethisterone acetate

To compare the uterine effects of 60 mg of raloxifene with a continuous combined hormone replacement therapy, a preparation of 2 mg 17beta-oestradiol (E(2)) and 1 mg norethisterone acetate for a duration of 12 months. A randomised, double-blind trial. Multicentre: Europe, Israel, South Africa. Asymptomatic postmenopausal women with risk factors for osteoporosis or cardiovascular disease who had an endometrial thickness of less than 5 mm. One thousand and eight women were randomised for the six month core; of these 420 were invited to continue into a six month extension period. Randomisation to either raloxifene or continuous combined hormone replacement therapy. Patients, recruiters and assessors were blinded to the treatment used. The frequency of vaginal spotting/bleeding as recorded in a diary, endometrial thickness and uterine volume as measured by transvaginal ultrasonography at baseline and after 6 and 12 months. After six months of therapy with raloxifene, the rate of women on raloxifene reporting vaginal bleeding and spotting (6.8%) was similar to the rate in the lead-in phase (8.3%) but increased from 7.0% to 55.1% in the continuous combined hormone replacement therapy group. Raloxifene treatment was not associated with a significant change from baseline to endpoint in mean endometrial thickness (P = 0.11), whereas continuous combined hormone replacement therapy treatment was associated with an increase in this value of mean (SD) of 1.2 (2.2) mm (P < 0.001). Compared with raloxifene, mean endometrial thickness for women on continuous combined hormone replacement therapy was significantly increased at endpoint [4.6 (2.1) mm vs 3.5 (1.7) mm; change from baseline P < 0.001]. In the raloxifene group, there was a trend towards a decrease from baseline in uterine volume [from 31.4 (20.3) to 30.3 (16.2) mm; P = 0.37]; in the continuous combined hormone replacement therapy group, there was a significant increase in uterine volume [from 31.3 (16.3) to 54.0 (36.1) mm; P < 0.001], and the difference in the effect of both compounds on change in uterine volume at endpoint reached statistical significance (P < 0.001). Statistically significant differences between the treatment groups were sustained for all parameters during the extension period. Early discontinuation rates, both overall and due to adverse events, were significantly lower (P < 0.001) in the raloxifene group after 6 and 12 months. Compared with continuous combined hormone replacement therapy, 6 and 12 months of raloxifene treatment do not lead to vaginal bleeding/spotting, are not associated with increased endometrial thickness or uterine volume and result in a significantly lower rate of early treatment discontinuations in asymptomatic women receiving treatment to prevent long term postmenopausal health risks.

Uterine Evaluation in Turner Syndrome: A Preliminary Study With Doppler Ultrasound

Background Since the advent of in vitro fertilization and donor ovum technology, patients with Turner syndrome, previously infertile due to ovarian failure, now have an opportunity to conceive and carry a pregnancy. This new opportunity has refocused attention on nonnal uterine growth and development in Turner syndrome. Prior studies of the uterus in Turner syndrome have utilized ultrasound measurement of the uterus to describe uterine characteristics and, in the absence of estrogen replacement therapy (ERT) or endogenous estrogen production, have found the uterine size to be almost unifonnly prepubertal irrespective of the age of the patient. No studies to date have assessed uterine blood flow by Doppler velocimetry in patients with Turner syndrome. Uterine blood flow is regulated by many factors but primarily by gonadal sex steroid hormones. In postmenopausal women on ERT a reduction in resistance to blood flow is seen. suggesting an increase in uterine perfusion with ERT. Whether this relationship is true in the patient with Turner syndrome is unknown. Methods We studied eleven patients with Turner syndrome by transabdominal pelvic ultrasound and evaluated, by Doppler velocimetty, the uterine artery pulsatility index (PI), calculated by (systolic – diastolic)/mean. Patients ranged in age from 5–17 (median 14). Pubertal development was assessed by Tanner staging, and height, weight and karyotype was recorded for all patients. Patients were placed on estrogen replacement therapy to initiate puberty, including type and dose of ERT, at the discretion of their physician. The ultrasonographer was blinded to the presence or absence of ERT. At the time of the first ultrasound, 6 patients were taking ERT, 2 on estrogen alone, 3 on cyclic estrogen/progestin (although all studies were performed on estrogen only day) and one was on an oral contraceptive. Mean duration of estrogen exposure was 23 months. One patient had spontaneous pubertal development and 4 patients had received no estrogen treatment and were Tanner I in development. At the time of ultrasound, uterine volume, cervix/fundus ratio and the presence of visible ovaries were also recorded. Results The mean uterine artery PI of patients with estrogen exposure was 2.21(± 1.23) and the mean of the unexposed group was 3.99(± 1.04). This suggests a trend toward decreased uterine artery resistance in the patients with estrogen exposure (p = 0.07 by Mann-Whitney test). The lowest PI was seen in the patient with spontaneous pubertal development. Uterine volume was significantly larger in the estrogen exposed group, 38.7 cm3 ± 23.3 in the estrogen exposed and 1.32 cm3 ± 0.9 in the non-exposed group. (p = 0.01 by Mann-Whitney test). Conclusion In the patient with Turner syndrome, estrogen exposure is associated with a corresponding increase in uterine volume and a trend toward decreased uterine artery resistance. Further study and continued prospective follow-up will indicate whether estrogen treatment in those patients studied prior to estrogen replacement is associated with similar changes.

Gestation and placentation in two New World opossums: Didelphis virginiana and Monodelphis domestica.

Estrus, gestation, and placentation were studied in the Virginia opossum (Didelphis virginiana) and the gray short-tailed oppossum (Monodelphis domestica), representatives of the prototypic, New World marsupial family Didelphidae. Didelphis is a large (3,000 g), pouched opossum that exhibits a 28-day estrous cycle, spontaneous estrus and ovulation, and a high ovulation rate (60 ova per cycle). Monodelphis is a small (100 g), pouchless opossum with male-induced estrus and ovulation and a moderate ovulation rate (12 ova per cycle). Implantation occurs on day 10 of the 13-day gestation period in Didelphis and on day 12 of the 15-day gestation in Monodelphis. Gestation and placentation, including the ultrastructural features of trophoblastic apposition to the uterine mucosa, are very similar in Didelphis and Monodelphis. Differences, such as a larger increase in uterine volume and a more highly folded endometrium following implantation in Monodelphis are minor. They appear to be related to the smaller maternal body size and the relatively larger uterine load of embryos in Monodelphis. Because body size is one of the major variables among New World marsupials, the descriptions of gestation and placentation presented here for Didelphis and Monodelphis, provide a basis for comparison in future studies of didelphid marsupials.

Progesterone deficiency and premature labour.

Plasma oestradiol 17beta and progesterone levels in 11 patients admitted to hospital for threatened premature labour of unknown aetiology were compared with those of women at similar stages of gestation whose pregnancy was normal. Oestradiol levels in the study group were slightly higher than in the normal controls but their progesterone levels were significantly lower. This progesterone deficiency increased the oestradiol/progesterone ratio in the study group patients, and it increased still more as the progesterone withdrawal continued during premature labour.Since uterine activity during pregnancy is regulated by a balanced action of several factors a deficiency in progesterone, an opponent of uterine activity, creates a regulatory imbalance which, if uncorrected, provokes premature labour. An increase in uterine volume stimulates uterine activity, and the present study reinforced our previous conclusion that the uterine-volume/plasma-progesterone ratio is a more accurate measure of the state of regulatory balance than the progesterone level alone.The cause of the progesterone deficiency in these cases remains unexplained, but we suggest that placental growth and function are contributory factors. We are investigating ways of correcting the resulting imbalance in the regulatory mechanism.

Peripheral plasma progesterone levels during human pregnancy and labor

Circulating plasma progresterone levels have been measured in 12 hospitalized, obstetrically normal, nulliparous patients during the last 7 weeks of gestation and spontaneous labor. A total of 92 blood samples were collected sequentially and analyzed by 3 independent investigators using the protein-binding method. Plasma progesterone reached peak values at different times during the last 4 weeks of gestation in individual patients but subsequently decreased slightly with the onset of clinical labor. This finding may be significant, in that it indicates a terminal failure in increased placental progesterone genesis, at a time when thecontinued increase in uterine volume promotes myometrial activity through a stretch effect.

Changes in uterine volume following the intra-amniotic injection of hypertonic saline.

A 30% increase in uterine volume during the initial 3 hours after intra‐amniotic saline injection has been calculated from 53 amniograms in 8 midtrimester patients.

The influence of the ovarian hormones on the actomyosin content and the development of tension in uterine muscle.

SUMMARY Actomyosin concentrations and tensions were measured in the rabbit uterus during pregnancy and in ovariectomized hormone-treated animals. The results showed that actomyosin concentration and tension in g./mm.2 longitudinal muscle followed similar courses during pregnancy. This was not so in the hormone-treated animals. Small quantities of oestrogen were sufficient in ovariectomized animals to produce a major difference between the untreated and treated animals. With higher doses only the concentration of the actomyosin increased linearly. During pregnancy a significant correlation was found between the number of foetuses in each horn, the quantity of actomyosin and the weight of the horn. The major increase in tension and actomyosin concentration occurred in the last half of pregnancy when the increase in uterine volume accelerates. The importance of this growth, as opposed to hormonal environment, was further emphasized by experiments in unilaterally pregnant rabbits in which both these quantities were significantly greater in the parous horn than in the non-parous horn. The effects of progesterone were also investigated.