Corticotropin-releasing hormone, stress and human reproduction: an update.

The stress system has suppressive effects on female and male reproductive function. Corticotrophin-releasing hormone (CRH), the principal regulator of stress, has been identified in the female and male reproductive system. Reproductive CRH participates in various reproductive functions that have an inflammatory component, where it serves as an autocrine and paracrine modulator. These include ovarian and endometrial CRH, which may participate in the regulation of steroidogenesis and the inflammatory processes of the ovary (ovulation and luteolysis) and the endometrium (decidualization and blastocyst implantation) and placental CRH, which is secreted mostly during the latter half of pregnancy and is responsible for the onset of labor. It has been suggested that there is a "CRH placental clock" which determines the length of gestation and the timing of parturition and delivery. The potential use of CRH-antagonists is presently under intense investigation. CRH-R1 antagonists have been used in animal studies to elucidate the role of CRH in blastocyst implantation and invasion, early fetal immunotolerance and premature labor. The present review article focuses on the potential roles of CRH on the physiology and pathophysiology of reproduction and highlights its participation in crucial steps of pregnancy, such as implantation, fetal immune tolerance, parturition and fetal programming of the hypothalamic-pituitary-adrenal (HPA) axis.

CRH-like peptides in human reproduction.

CRH and Urocortins 1, 2 and 3 comprise the, so far identified, members of the CRH family of peptides in humans. Their actions are mediated through two distinct receptors, CRHR1 and CRHR2, encoded by different genes. CRH-like peptides and their receptors have been identified in reproductive tissues, such as the ovary, uterus as well as fetal and placental membranes. The participation of the "CRH family" of peptides and receptors in the physiology of these organs is currently under intense investigation. During the estrus cycle, endometrial CRH acts as a fine tuner of stromal cells decidualization. CRH is produced by embryonic trophoblast and maternal decidual cells and plays important roles in implantation. CRH also participates in the control of trophoblast invasion. Furthermore, placental CRH and Urocortin are involved in the mechanisms controlling maintenance of pregnancy and the onset of labor. The level of participation of urocortins 2 and 3 in these phenomena is currently under investigation. This review will focus on existing data on the expression and regulation of the CRH family of peptides and their receptors in the female reproductive system, as well as in their potential biologic role(s) in human reproductive functions.

Intratumoral CRH modulates immuno-escape of ovarian cancer cells through FasL regulation.

Although corticotropin-releasing hormone (CRH) and Fas ligand (FasL) have been documented in ovarian carcinoma, a clear association with tumour progression and immuno-escape has not been established. FasL plays an important role in promoting tumour cells' ability to counterattack immune cells. Here, we examined immunohistochemically the expression of CRH, CRHR1, CRHR2 and FasL in 47 human ovarian cancer cases. The ovarian cancer cell lines OvCa3 and A2780 were further used to test the hypothesis that CRH might contribute to the immune privilege of ovarian tumours, by modulating FasL expression on the cancer cells. We found that CRH, CRHR1, CRHR2 and FasL were expressed in 68.1, 70.2, 63.8 and 63.8% of the cases respectively. Positivity for CRH or FasL expression was associated with higher tumour stage. Finally, CRH increased the expression of FasL in OvCa3 and A2780 cells through CRHR1 thereby potentiated their ability to induce apoptosis of activated peripheral blood lymphocytes. Corticotropin-releasing hormone produced by human ovarian cancer might favour survival and progression of the tumour by promoting its immune privilege. These findings support the hypothesis that CRHR1 antagonists could potentially be used against ovarian cancer.

Abortion is associated with increased expression of FasL in decidual leukocytes and apoptosis of extravillous trophoblasts: a role for CRH and urocortin.

Human reproduction is remarkably inefficient, with more than half of spontaneous conceptions failing to complete the first trimester. However, little is known on the molecular events that take place at the implantation site during abortion. Here, we examined the hypothesis that the expression of the proapoptotic Fas/FasL system at the implantation site is impaired in abortions. We found that, in contrast to normal pregnancy, abortive deciduas contain leukocytes that are positive for FasL and extravillous trophoblasts (EVTs), which show increased expression of Fas and increased rates of apoptosis. In addition, the neuropeptides, corticotropin-releasing hormone and urocortin, were elevated in placental material obtained from abortions. In vitro, these peptides induced the expression of FasL in decidual lymphocytes (DL) obtained from elective termination of pregnancy placentas and thus potentiated the cells' ability to induce Fas-mediated apoptosis in an EVT-based hybridoma cell line. Finally, DL from abortion sites effectively induced apoptosis of EVT without prior treatment. It is possible that these events may impede successful early placentation and thus contribute to the pathophysiology of human abortion.

The role of corticotropin-releasing hormone in blastocyst implantation and early fetal immunotolerance.

During blastocyst implantation, the maternal endometrial response to the invading semi-allograft has characteristics of an acute, aseptic inflammatory response. However, once implanted, the embryo suppresses this response and prevents rejection. Simultaneously, the mother's immune system prevents a graft VS. host reaction deriving from the fetal immune system. We have shown that embryonic trophoblast and maternal decidua cells, i.e., cells located in the interface between the fetal placenta and the maternal endometrium, produce corticotropin-releasing hormone (CRH) and express Fas ligand. CRH may play a crucial role in the implantation and the anti-rejection process that protects the fetus from the maternal immune system, primarily by killing activated T cells through the Fas-FasL interaction. In experimental animals, type 1 CRH receptor (CRH-R1) blockade by antalarmin, a specific type 1 CRH receptor antagonist, decreased implantation sites by approximately 70%. CRH is also involved in controlled trophoblast invasion, by downregulating the synthesis of the carcinoembryonic antigen-related cell adhesion molecule 1 by extravillous trophoblast cells. IN VITRO findings showed that CRH-R1 blockade by antalarmin increased trophoblast invasion by approximately 60%. Defective uterine CRH/CRH-R1 system during early pregnancy may be implicated in the pathophysiology of recurrent miscarriage, placenta accreta, and preeclampsia.

Stress and the female reproductive system.

The hypothalamic-pituitary-adrenal (HPA) axis, when activated by stress, exerts an inhibitory effect on the female reproductive system. Corticotropin-releasing hormone (CRH) inhibits hypothalamic gonadotropin-releasing hormone (GnRH) secretion, and glucocorticoids inhibit pituitary luteinizing hormone and ovarian estrogen and progesterone secretion. These effects are responsible for the "hypothalamic" amenorrhea of stress, which is observed in anxiety and depression, malnutrition, eating disorders and chronic excessive exercise, and the hypogonadism of the Cushing syndrome. In addition, corticotropin-releasing hormone and its receptors have been identified in most female reproductive tissues, including the ovary, uterus, and placenta. Furthermore, corticotropin-releasing hormone is secreted in peripheral inflammatory sites where it exerts inflammatory actions. Reproductive corticotropin-releasing hormone is regulating reproductive functions with an inflammatory component, such as ovulation, luteolysis, decidualization, implantation, and early maternal tolerance. Placental CRH participates in the physiology of pregnancy and the onset of labor. Circulating placental CRH is responsible for the physiologic hypercortisolism of the latter half of pregnancy. Postpartum, this hypercortisolism is followed by a transient adrenal suppression, which may explain the blues/depression and increased autoimmune phenomena observed during this period.

Factors affecting outcome after incomplete excision of cervical intraepithelial neoplasia.

PURPOSE: Conservative treatment for cervical intraepithelial neoplasia (CIN) by ablative or excisional techniques is widely used. However, women with incomplete excision have a variable risk of CIN recurrence. The aim of this study was to identify possible risk factors for recurrence of CIN after large loop excision of the transformation zone (LLETZ) with involved margins of excision. METHODS: All cases of women treated with LLETZ for CIN between 1989-2000, in whom histological evaluation of the excised specimen revealed extension of CIN to the excision margins, were retrospectively studied. A woman was considered to have recurrence when she had histologically confirmed CIN following a second LLETZ or hysterectomy during the follow-up period. The characteristics that were examined as possible risk factors were age, parity, smoking habit, grade of initial lesion and extension to the endo- or ectocervical margin. RESULTS: Treatment failure was diagnosed in 18 out of 65 (27.7%) women with involved margins. The only characteristic that reached statistical significance was age. The mean age of women with recurrence was 35.8 years, whereas the mean age of women without recurrence was 32.8 years (p = 0.044). Also, a trend was evident in women with high-grade initial lesions (CIN II-III) (p = 0.168) and involvement of the endocervical margins (p = 0.149). No differences were observed between the two groups regarding parity and smoking habit. CONCLUSIONS: Increased age is a risk factor for recurrence in women with incomplete excision of CIN after LLETZ. Larger studies are required for definite conclusions.

Successful myomectomy during pregnancy.

BACKGROUND: Although leiomyomas usually remain asymptomatic during pregnancy, they may complicate its course. In this study, pregnancy outcome observed when myomectomy was performed during pregnancy in carefully selected patients is presented. METHODS: A prospective cohort study of 13 women who underwent myomectomy during pregnancy between January 1994 and December 2001. Surgical management of leiomyoma was required on the basis of characteristics of the myoma and symptoms. RESULTS: Among a total of 15,579 women registered at the authors' prenatal clinic, 622 consecutive pregnant women had sonographically identified myoma; hence, the incidence was 3.9% (95% CI 3.6-4.3%). The vast majority of these women was asymptomatic during pregnancy or managed conservatively (97.4%; 95% CI 96-98%). Among 622 pregnant patients with leiomyoma, 13 presented with complications during pregnancy that required surgical intervention (2.1%; 95% CI 0.9-3.2%), due to increase in lesion size causing discomfort and/or severe abdominal pain not responding to conservative management with analgesic and non-steroidal anti-inflammatory drug medication. In 92% of these cases, successful myomectomy was performed and the pregnancy progressed to term without further complications. CONCLUSIONS: These data provide reassurance for pregnant women with uterine myoma. Surgical management of uterine leiomyoma during pregnancy may be successfully performed in carefully selected patients.

Early pregnancy termination with vaginal misoprostol before and after 42 days gestation.

BACKGROUND: Misoprostol is a prostaglandin E(1) analogue that has been used for medical abortion. We conducted this prospective study to compare the efficacy of vaginal misoprostol for abortion in women at a gestational age of <42 days and in women at a gestational age of 42-56 days. METHODS: A total of 160 women seeking medical termination of a pregnancy of <56 days were enrolled in the study. Medical termination was performed using 800 micro g of vaginal misoprostol, repeated every 24 h for a maximum of three doses. RESULTS: The overall complete abortion rate was 91.3%. In group A (gestation <42 days) complete abortion occurred in 96.3% of women, whereas in group B (gestation = 42-56 days) complete abortion occurred in 86.3% of women (P < 0.025). The two groups did not differ significantly with respect to side-effects (incidence of pain, bleeding, nausea, diarrhoea, fever and headache). Women who had aborted successfully were significantly more satisfied with the method compared with women who did not (P < 0.001). CONCLUSIONS: The vaginal misoprostol-alone regimen is highly effective for women seeking medical abortion of pregnancies of

Surgical management of early stage cervical cancer: ten years experience from one Greek health region.

PURPOSE OF INVESTIGATION: Cervical cancer is the second most common malignancy in women, in both incidence and mortality. In the present study, we report our results of treating 93 consecutive patients with early invasive cervical cancers (Stages I-IIA). METHODS: The patients of this study comprised all women recognized with stage I-IIA cervical cancer during 1991-2000. Patients with stage IA1 cervical cancer without lymphvascular space involvement underwent either conservative management by means of large loop conization or simple hysterectomy. The remaining patients underwent radical hysterectomy and lymphadenectomy or radiation therapy. Mean (+/- SD) duration of follow-up was 6 (+/- 1.7) years. RESULTS: The mean (+/- SD) age of patients with stage I-IIA cervical cancer was 41.3 (+/- 9.1) year. Thirty-five patients with stage [A1 disease were managed conservatively with loop excision and 19 patients subsequently became pregnant. Fifty-two patients with stage IA2, IB and IIA cervical carcinoma underwent radical hysterectomy and lymphadenectomy. CONCLUSION: Young women with stage IA1 cervical carcinoma wishing future fertility who undergo loop excision have a 100% cure rate. Women with stage IA2, IB, and IIA cervical cancer should undergo radical hysterectomy and lymphadenectomy or radiation therapy.

Screening transvaginal uterine ultrasonography for identifying endometrial pathology in postmenopausal women.

BACKGROUND: During the last decade, transvaginal ultrasonography (TVS) has become a widely-used technique for the evaluation of endometrial histology. The purposes of this study were to compare transvaginal sonographic evaluation of the endometrium with histology obtained by endometrial biopsy in asymptomatic postmenopausal women and to determine whether screening transvaginal sonography might be useful in the evaluation of postmenopausal women. MATERIALS AND METHODS: The study included 59 unselected asymptomatic postmenopausal women who attended the outpatients' clinic for annual cervical cytology at Ioannina University Hospital, Greece. The women were evaluated by transvaginal scans, performed immediately before endometrial biopsy. RESULTS: In the 43 women with a histopathological diagnosis of normal endometrium/inadequate for assessment/atrophy, the mean endometrial thickness was 5.1 +/- 3.3 mm (range 0.8-13.8 mm) whereas the corresponding value in the 16 women with abnormal findings was 17.6 +/- 4.3 mm (range 9.4-24.6 mm) (p<0.001). If a 9-mm cut-off limit was used for endometrial thickness, the sensitivity, specificity and positive predictive value were 100%, 90.69% and 80%, respectively. CONCLUSION: TVS is a sensitive test for determining endometrial disease in asymptomatic postmenopausal women. However, well-designed studies should be conducted, completed, analysed and validated before a mass-screening program using TVS is implemented.

Transvaginal uterine ultrasonography compared with endometrial biopsy for the detection of endometrial disease in perimenopausal women with uterine bleeding.

BACKGROUND: Almost 70% of all gynecological consultations in perimenopausal women are related to irregular uterine bleeding. In this prospective study, we compared endometrial assessment by transvaginal ultrasonography (TVS) in perimenopausal women with irregular uterine bleeding to histological assessment and tested whether the TVS was effective as a diagnostic tool for the detection of endometrial pathology in these women. MATERIALS AND METHODS: Eighty consecutive perimenopausal women complaining of irregular uterine bleeding participated in the study. The women were evaluated by transvaginal scans, performed immediately before endometrial biopsy. The ultrasonographic results were compared with the histological diagnosis obtained from the endometrial biopsy. RESULTS: Sixty-seven out of 80 women (83.7%) had normal histological findings, whereas 13 (16.3%) had abnormal findings. No endometrial cancer was diagnosed in this cohort of women. In the 67 women with a histological diagnosis of normal endometrium, mean+/-SD endometrial thickness was 10.5+/-4.0 mm (range 4.0-18.5 mm), whereas the corresponding value in the 13 women with abnormal findings was 18.7+/-3.8 mm (range 13.5-22.5 mm). If a 13 mm cut-off limit was used for endometrial thickness, which would include all abnormal cases, the sensitivity, specificity and positive predictive values were 100%, 71.64% and 40.62%, respectively. CONCLUSION: TVS can identify women with perimenopausal bleeding in which the likelihood of endometrial pathology is high and in which tissue sampling should be performed. Thus, TVS can be a primary method of selecting women with perimenopausal bleeding who must be further investigated with more invasive methods such as endometrial biopsy.

Screening transvaginal uterine ultrasonography for identifying endometrial pathology in postmenopausal women.

BACKGROUND: During the last decade, transvaginal ultrasonography (TVS) has become a widely-used technique for the evaluation of endometrial histology. The purposes of this study were to compare transvaginal sonographic evaluation of the endometrium with histology obtained by endometrial biopsy in asymptomatic postmenopausal women and to determine whether screening transvaginal sonography might be useful in the evaluation of postmenopausal women. MATERIALS AND METHODS: The study included 59 unselected asymptomatic postmenopausal women who attended the outpatient clinic for annual cervical cytology at Ioannina University Hospital Greece. The women were evaluated by transvaginal scans, performed immediately before endometrial biopsy. RESULTS: In the 43 women with a histopathological diagnosis of normal endometrium/inadequate for assessment/atrophy, the mean endometrial thickness was 5.1 +/- 3.3 mm (range 0.8-13.8 mm) whereas the corresponding value in the 16 women with abnormal findings was 17.6 +/- 4.3 mm (range 9.4-24.6 mm) (p<0.001). If a 9 mm cut-off limit was used for endometrial thickness, the sensitivity, specificity and positive predictive value were 100%, 90.69% and 80%, respectively. CONCLUSION: TVS is a sensitive test for determining endometrial disease in asymptomatic postmenopausal women. However, well-designed studies should be conducted, completed, analysed and validated before a mass-screening program using TVS is implemented.

Bacteriological cultures of removed intrauterine devices and pelvic inflammatory disease.

Intrauterine devices (IUDs) are highly effective, long-term methods of contraception. Although evidence of a direct association between IUD use and pelvic inflammatory disease (PID) is scarce, concerns about PID related to IUDs use has limited their use throughout the world. We designed this study to examine the effect of IUDs on PID. For the study, we recruited 200 participants from among women who requested an IUD as a means of contraception. The IUDs were removed 36 months later or in case of PID. No PID cases were recorded during the follow-up period. Prior to IUD insertion, 121 women (60.5%) had symptoms and/or signs of lower genital tract infection, whereas during the follow-up period 179 women (89.5%) had symptoms and/or signs of lower genital tract infection. The Papanicolaou smears were negative for Actinomyces throughout the study period. Also, cultures for sexualy transmitted disease microorganisms were negative throughout the study period. Following IUD removal, 189 IUD cultures (94.5%) were positive. The bacterial flora of the removed IUDs consisted of common aerobic and anaerobic microorganisms that do not account for PID. The most common microorganisms identified were Staphylococcus coagulase negative, Eschericia coli, and Enterococcus faecalis. IUDs are a very effective and safe method of contraception if potential recipients are selected carefully. Culture of the removed IUDs and therapeutic management of women with positive cultures are not recommended when women are asymptomatic for PID.

Molecular defects causing ovarian dysfunction.

The functions of the hypothalamic-pituitary-ovarian and -adrenal axes are intertwined, and molecular defects in either axis may cause ovarian dysfunction. Advances in molecular genetics have allowed new insights into the pathophysiology of ovarian disorders. Specific gene mutations causing delayed puberty and/or ovarian failure, and heterosexual or isosexual precocious puberty have recently been described. The molecular insights gained into ovarian dysfunction have already led to rational therapies for some of these conditions.

Premature ovarian failure is not premature menopause.

Normal menopause occurs at an average age of 50 and results from ovarian follicle depletion. Normal menopause is an irreversible condition, whereas premature ovarian failure is characterized by intermittent ovarian function in half of these young women. These young women produce estrogen intermittently and sometimes even ovulate despite the presence of high gonadotropin levels. Indeed, pregnancy has occurred after a diagnosis of premature ovarian failure. On pelvic ultrasound examination, follicles were equally likely to be detected in patients more than 6 years after a diagnosis of premature ovarian failure as in patients less than 6 years after the diagnosis. Thus, the probability of detecting a follicle appears to remain stable during the normal reproductive lifespan of these young women. Indeed, pregnancy was reported in a 44-year-old woman 16 years after a diagnosis of premature ovarian failure. No treatment to restore fertility in patients with premature ovarian failure has proved to be safe and effective in prospective controlled studies. Theoretically, these unproved therapies might even prevent one of these spontaneous pregnancies from occurring.

Treatment of autoimmune premature ovarian failure.

There is no known immunosuppressive therapy for autoimmune premature ovarian failure that has been proven safe and effective by prospective randomized placebo-controlled study. Nevertheless, immunosuppression using corticosteroids has been used on an empirical basis for this condition. Here we present two cases of young women with premature ovarian failure who were treated with glucocorticoids in the hopes of restoring fertility. The first case illustrates the potential benefit of such therapy, and the second case illustrates a potential risk. The first patient with histologically proven autoimmune oophoritis was treated with alternate day glucocorticoid treatment. She had return of menstrual bleeding six times and ovulatory progesterone concentrations four times over a 16 week period. The second patient with presumed but unconfirmed autoimmune ovarian failure was referred to us after having been treated with a 9 month course of corticosteroids. During that treatment her menses did not resume. The corticosteroid treatment was complicated by iatrogenic Cushing syndrome and osteonecrosis of the knee. Identifying patients with autoimmune premature ovarian failure presents the opportunity to restore ovarian function by treating these patients with the proper immune modulation therapy. On the other hand, potent immune modulation therapy can have major complications. Corticosteroid therapy for autoimmune premature ovarian failure should be limited to use in placebo-controlled trials designed to evaluate the safety and efficacy of such treatment.

Spontaneous evolution of human papillomavirus infection in the uterine cervix.

BACKGROUND: Little is known about the natural history and the malignant potential of low-grade cervical intraepithelial neoplasia associated with human papillomavirus (HPV) infection. Cervical cancer remains the second most frequent cause of death in women across the world. Epidemiologic and molecular studies have shown that human papillomavirus (HPV) is associated with cervical carcinogenesis. In this prospective study we examined the behavior of low-grade cervical intraepithelial lesions associated with HPV infection over a 6-year period. MATERIAL AND METHODS: During 1992, women with Papanicolaou smears reporting koilocytotic atypia (HPV effect) with or without grade 1 cervical intraepithelial neoplasia (HPV +/- CINI, low grade squamous intraepithelial lesions, LgSIL), along with colposcopic impression of LgSIL were included to the study. Between 1992 and 1998 all women underwent repeat Papanicolaou smears, colposcopic evaluation and HPV DNA testing every six months. HPV typing of cervical scrapes was done by PCR. RESULTS: A total of 330 women completed at least 6 years of follow up. Among women with high-risk HPV types (16/18), the presence of dysplasia (grade 1 cervical intraepithelial neoplasia) was significantly correlated with the progression of the lesion; 29% of cases with HPV + CINI (15 out of 75) progressed to more severe lesions versus only 9% of cases with HPV infection (18 out of 225), P < 0.001, chi-square test. The incidence of histologically confirmed progressive lesions was significantly greater in women with mild dysplasia (18 out of 75, 24%) compared to women without dysplasia (13 out of 255, 5%), P < 0.001, chi-square test. CONCLUSIONS: In our study HPV typing was not predictive of the evolution of low-grade intraepithelial lesions associated with HPV infection. Standard cytologic screening and colposcopy are the most effective means of monitoring low-grade lesions.

Human follicle fluid vascular endothelial growth factor concentrations are correlated with luteinization in spontaneously developing follicles.

Vascular endothelial growth factor (VEGF) is a cytokine that induces angiogenesis. Angiogenesis is a prominent histologic component of the luteinization process. Luteinization is also characterized by granulosa cell progesterone secretion in response to the luteinizing hormone (LH) surge. Local VEGF production in human pre-ovulatory follicles, induced by LH, was postulated to be a luteinization mediator in women. To investigate this hypothesis, serum and fluid from the dominant follicle of 31 healthy regularly cycling multiparous women undergoing laparoscopic sterilization were obtained. VEGF was measured by enzyme-linked immunosorbent assay, and LH and progesterone were measured by radioimmunoassay. Follicle aspiration was performed at a median of 13 days from the last menstrual period (range 11-17 days). The median pre-ovulatory follicle diameter was 16 mm (range 11-23 mm). Follicle fluid VEGF concentrations (mean 6900 pg/ml, range 1200-17 100 pg/ml) were correlated positively with follicle fluid progesterone concentrations (mean 10 176 nmol/l, range 636-66780 nmol/l, r=0.62, P=0.002). This correlation was even tighter (r=0.87, P < 0.0001) when only samples from the 22 women in the earliest stages of follicle luteinization were considered. In these women serum LH concentrations were also correlated with follicle fluid VEGF concentrations (r=0.51, P=0.02). Our findings demonstrate the close dynamic relationship between VEGF production and early luteinization in human follicles during normal non-stimulated cycles.

The role of deoxyribonuclease I in amniotic fluid during pregnancy and labour.

The purpose of this study was to detect the presence, and determine the normal values and the significance of DNase I in the amniotic fluid and in human placentas. Fifty-one pregnant women at 16-22 weeks of gestation and 89 women in spontaneous labour at term were recruited to the study. DNase I activity was measured in amniotic fluid and cytoplasmic extracts from the fetal portion of placentas by using a spectrophotometric technique (DNA precipitation assay) and nucleic acid electrophoresis, following degradation of the DNA by the enzyme. DNase I activity was undetectable in the placental cytoplasmic extracts. In the second trimester of pregnancy DNase I activity was detectable in amniotic fluid (2.3+/-0.64x10(5) U/l). During labour DNase I activity was also detectable, but reduced levels were observed in the presence of clear amniotic fluid, compared to second trimester levels, (1.9+/-0.44x10(5) U/l, P<0.001), whereas higher levels were found in the presence of meconium-stained amniotic fluid compared to both second trimester and clear amniotic fluid at labour (11.4+/-4.1x10(5) U/l, P<0.001 and P<0.001, respectively). Three out of 17 fetuses with meconium-stained amniotic fluid (18%) developed perinatal infection. In conclusion, the detection of DNase I activity in the amniotic fluid of second and third trimester indicates a physiological role in human pregnancy. DNase I activity normally decreases at term, compared to second trimester levels, but increases significantly in the presence of meconium.