Early and late preterm birth rates in participants adherent to randomly assigned high dose docosahexaenoic acid (DHA) supplementation in pregnancy

BACKGROUND

Intention-to-treat analyses do not address adherence. Per protocol analyses treat nonadherence as a protocol deviation and assess if the intervention is effective if followed.

OBJECTIVE

To determine the rate of early preterm birth (EPTB, <34 weeks gestation) and preterm birth (PTB, <37 weeks gestation) in participants who adhered to a randomly assigned docosahexaenoic acid (DHA) dose of 1000 mg/day.

STUDY DESIGN

Eleven hundred women with a singleton pregnancy were enrolled before 20-weeks' gestation, provided a capsule with 200 mg/day DHA and randomly assigned to two additional capsules containing a placebo or 800 mg of DHA. In the Bayesian Adaptive Design, new randomization schedules were determined at prespecified intervals. In each randomization, the group with the most EPTB was assigned fewer participants than the other group. Adherence was defined a priori as a postpartum red blood cell phospholipid DHA (RBC-PL-DHA) ≥5.5%.and post hoc as ≥8.0% RBC-PL-DHA, the latter after examination of postpartum RBC-PL-DHA. Bayesian mixture models were fitted for gestational age and dichotomized for EPTB and PTB as a function of baseline RBC-PL-DHA and dose-adherence. Bayesian hierarchical models were also fitted for EPTB by dose adherence and quartiles of baseline RBC-PL-DHA.

RESULTS

Adherence to the high dose using both RBC-PL-DHA cut points resulted in less EPTB compared to 200 mg [Bayesian posterior probability (pp) = 0.93 and 0.92, respectively]. For participants in the two lowest quartiles of baseline DHA status, adherence to the higher dose resulted in lower EPTB (≥5.5% RBC-PL-DHA, quartiles 1 and 2, pp = 0.95 and 0.96; ≥8% RBC-PL-DHA, quartiles 1 and 2, pp = 0.94 and 0.95). Using the Bayesian model, EPTB was reduced by 65%, from 3.45% to 1.2%, using both cut points. Adherence also reduced PTB before 35, 36 and 37 weeks using both cut points (pp ≥ 0.95). In general, performance of the nonadherent subgroup mirrored that of participants assigned to 200 mg.

CONCLUSION

Adherence to high dose DHA reduced EPTB and PTB. The largest effect of adherence on reducing EPTB was observed in women with low baseline DHA levels.

CLINICALTRIALS

gov (NCT02626299).

Early pregnancy prediction of spontaneous preterm birth before 32 completed weeks of pregnancy using plasma RNA: transcriptome discovery and initial validation of an RNA panel of markers

OBJECTIVE

To compare the second-trimester plasma cell-free (PCF) transcriptome of women who delivered at term with that of women with spontaneous preterm birth (sPTB) at or before 32 weeks of gestation and identify/validate PCF RNA markers present by 16 weeks of gestation.

DESIGN

Prospective case-control study.

SETTING

Academic tertiary care centre.

POPULATION

Pregnant women with known outcomes prospectively sampled.

METHODS

PCF RNAs extracted from women at 22-24 weeks of gestation (five sPTB up to 32 weeks and five at term) were hybridised to gene expression arrays. Differentially regulated RNAs for sPTB up to 32 weeks were initially selected based on P value compared with control (P < 0.01) and fold change (≥1.5×). Potential markers were then reordered by narrowness of distribution. Final marker selection was made by searching the Metacore™ database to determine whether the PCF RNAs interacted with a reported set of myometrial Preterm Initiator genes. RNAs were confirmed by quantitative reverse transcription polymerase chain reaction and tested in a second group of 40 women: 20 with sPTB up to 32 weeks (mean gestation 26.5 weeks, standard deviation ±2.6 weeks), 20 with spontaneous term delivery (40.1 ± 0.9 weeks) sampled at 16-19+5  weeks of gestation.

MAIN OUTCOME MEASURE

Identification of PCF RNAs predictive of sPTB up to 32 weeks.

RESULTS

Two hundred and ninety-seven PCR RNAs were differentially expressed in sPTB up to 32 weeks of gestation. Further selection retained 99 RNAs (86 mRNAs and 13 microRNAs) and five of these interacted in silica with seven Preterm Initiator genes. Four of five RNAs were confirmed and tested on the validation group. The expression of each confirmed PCF RNA was significantly higher in sPTB up to 32 weeks of gestation. In vitro study of the four mRNAs revealed higher expression in placentas of women with sPTB up to 32 weeks and the potential to interfere with myometrial quiescence.

CONCLUSIONS

The PCF RNA markers are highly associated with sPTB up to 32 weeks by 16 weeks of gestation.

TWEETABLE ABSTRACT

Women destined for spontaneous preterm birth can be identified by 16 weeks of gestation with a panel of maternal plasma RNAs.

The active components of effective training in obstetric emergencies

Confidential enquiries into poor perinatal outcomes have identified deficiencies in team working as a common factor and have recommended team training in the management of obstetric emergencies. Isolated aviation-based team training programmes have not been associated with improved perinatal outcomes when applied to labour ward settings, whereas obstetric-specific training interventions with integrated teamwork have been associated with clinical improvements. This commentary reviews obstetric emergency training programmes from hospitals that have demonstrated improved outcomes to determine the active components of effective training. The common features identified were: institution-level incentives to train; multi-professional training of all staff in their units; teamwork training integrated with clinical teaching and use of high fidelity simulation models. Local training also appeared to facilitate self-directed infrastructural change.

Qualitative venous Doppler waveform analysis improves prediction of critical perinatal outcomes in premature growth-restricted fetuses

BACKGROUND

Our aim was to test the hypothesis that qualitative ductus venosus and umbilical venous Doppler analysis improves prediction of critical perinatal outcomes in preterm growth-restricted fetuses with abnormal placental function.

METHODS

Patients with suspected intrauterine growth restriction (IUGR) underwent uniform fetal assessment including umbilical artery (UA), ductus venosus (DV) and umbilical vein (UV) Doppler. Absent or reversed UA end-diastolic velocity (UA-AREDV), absence or reversal of atrial systolic blood flow velocity in the DV (DV-RAV) and pulsatile flow in the umbilical vein (P-UV) were examined for their efficacy to predict critical outcomes (stillbirth, neonatal death, perinatal death, acidemia and birth asphyxia) before 37 weeks' gestation.

RESULTS

Seventeen (7.6%) stillbirths and 16 (7.1%) neonatal deaths were observed among 224 IUGR fetuses. Forty-one neonates were acidemic (19.8%) and seven (3.1%) had birth asphyxia. Logistic regression showed that UA-AREDV had the strongest association with perinatal mortality (R(2) = 0.49, P < 0.001), stillbirth (R(2) = 0.48, P < 0.001) and acidemia (R(2) = 0.22, P = 0.002) while neonatal death was most strongly related to DV-RAV and P-UV (R(2) = 0.33, P = 0.007). UA waveform analysis offered the highest sensitivity and negative predictive value and DV-RAV and P-UV had the best specificity and positive predictive values for outcome prediction. Overall, DV-RAV or P-UV offered the best prediction of acidemia and neonatal and perinatal death irrespective of the UA waveform. In fetuses with UA-AREDV, prediction of asphyxia and stillbirth was significantly enhanced by venous Doppler.

CONCLUSION

Prediction of critical perinatal outcomes is improved when venous and umbilical artery qualitative waveform analysis is combined. The incorporation of venous Doppler into fetal surveillance is therefore strongly suggested for all preterm IUGR fetuses.

Prevalence of viral DNA in amniotic fluid of low-risk pregnancies in the second trimester

AIM

The association between fetal viral infection and adverse pregnancy outcome is well documented. However, the prevalence of common viral pathogens in the amniotic fluid of normal pregnancies is not established. The purpose of this study was to determine this prevalence in asymptomatic patients.

METHODS

This was a prospective observational study of patients at low risk for viral infection who were referred for second-trimester genetic amniocentesis. In patients with normal fetal anatomy on ultrasound and a normal fetal karyotype, a 2-ml aliquot of amniotic fluid obtained at amniocentesis was analyzed by multiplex polymerase chain reaction for cytomegalovirus (CMV), parvovirus B19, adenovirus, enterovirus, herpes simplex virus (HSV), respiratory syncytial virus (RSV) and Epstein-Barr virus (EBV).

RESULTS

Among 686 patients, advanced maternal age was the most common indication for genetic testing (n = 469, 68.4%), followed by elevated aneuploidy risk on triple screen (n = 164, 23.9%), elevated maternal serum alpha-fetoprotein (n = 20, 2.9%), previous aneuploidy (n = 16, 2.3%) and family history of inheritable disease (n = 14, 2.1%). Forty-four (6.4%) amniotic fluid samples were positive for viral genome. A single genome was amplified in 41 samples (93%). In three samples, two viral genomes were identified. Adenovirus was most frequently identified (37/44), followed by CMV (5/44), EBV (2/44), enterovirus (2/44) and RSV (1/44). Parvovirus and HSV were not identified. There was a bimodal seasonal variation in prevalence, with the highest prevalence during the summer and late winter.

CONCLUSION

Viral genome is commonly found in amniotic fluid with a sonographically normal fetus, and the prevalence follows a seasonal pattern. The mechanism, significance and effects of this asymptomatic viral presence require further study.

Pregnancy and estradiol decrease GTPase activity in the guinea pig uterine artery

The mechanisms by which pregnancy redistributes cardiac output in an organ-specific manner are poorly understood. We propose that it is consequential to estrogen-mediated alterations in G protein-mediated signal transduction. Aortas and uterine (UAs) and mesenteric arteries (MAs) were obtained from late-pregnant, nonpregnant, or ovariectomized guinea pigs chronically treated with 17beta-estradiol. High-affinity GTPase activity was assayed enzymatically. The cGMP generated in response to the endothelium-dependent agonist ACh was measured in UAs incubated with or without cholera toxin (CTX, which inhibits G(s)alpha). Pregnancy significantly decreased UA but not aorta or MA GTPase activity. 17beta-Estradiol decreased UA GTPase activity compared with untreated ovariectomized animals. ACh increased cGMP in pregnant but not nonpregnant UAs. Pretreatment of nonpregnant UAs with CTX increased ACh-induced cGMP levels similar to pregnancy. Thus pregnancy and estradiol decrease the GTPase activity of a CTX-sensitive G protein in UAs, increasing receptor-dependent cGMP release. This alteration in receptor-mediated G protein coupling in UAs may contribute to the characteristic cardiovascular adaptation to pregnancy.

Use of McRoberts' position during delivery and increase in pushing efficiency

McRoberts' position is used during the second stage of labour to facilitate delivery of the fetal shoulders. Few clinical studies have been done to measure its efficacy. We measured intrauterine pressure in 22 women in term labour, after the vertex reached 3+ station, in the dorsal lithotomy position. Patients pushed with legs either in stirrups or hyperflexed by 1358 (McRoberts' position). Maternal valsalva transiently increased the expulsive force by 32% over naturally occurring contractions. Use of McRoberts' position almost doubled the intrauterine pressure developed by contractions alone (from 1653 mm Hg s to 3262 mm Hg s [97%]).

Leveraging healthcare for the greater good: lessons learned from the National Centers of Excellence in Women's Health

The creation of the National Centers of Excellence in Women's Health (CoE) program in 1996 by the Office on Women's Health, Department of Health and Human Services, included the stipulation that each institution awarded a CoE contribute at least a 25% match for the federal funds. Even the combination of these two sources of monies was insufficient for each CoE to accomplish its goals, however, so leveraging funds became necessary for each CoE to function effectively. The forms of leveraging varied from CoE to CoE, in part as a result of the institutional environment and the unique possibilities each permitted and in part as a result of the creativity of the leaders of the CoEs. This paper describes the concepts and some applications of leveraging in the setting of the CoEs, which might be applicable to other settings as well.

Pregnancy enhances G protein activation and nitric oxide release from uterine arteries

We hypothesized that pregnancy modulates receptor-mediated responses of the uterine artery (UA) by altering G protein activation or coupling. Relaxation and contraction to NaF (0.5-11.5 mM), acetylcholine (10(-9)-10(-5) M), and bradykinin (10(-12)-3 x 10(-5) M) were measured in isolated UA of pregnant and nonpregnant guinea pigs. Responses were measured in the presence and absence of either cholera toxin (2 microg/ml) or pertussis toxin (Galpha(s) and Galpha(i) inhibitors, respectively). NaF relaxation was endothelium dependent and nitro-L-arginine sensitive (a nitric oxide synthase inhibitor). Relaxation to NaF, acetylcholine, and bradykinin were potentiated by pregnancy. Cholera but not pertussis toxin increased relaxation to acetylcholine and bradykinin in UA from nonpregnant animals, had no effect in UA from pregnant animals, and abolished the pregnancy-induced differences in acetylcholine relaxation. Cholera toxin potentiated the bradykinin-induced contraction of UA of both pregnant and nonpregnant animals, whereas pertussis toxin inhibited contraction of UA from pregnant animals only. Therefore, pregnancy may enhance agonist-stimulated endothelium-dependent relaxation and bradykinin-induced contraction of UA by inhibiting GTPase activity or enhancing Galpha(s) but not Galpha(i) activation in pregnant animals. Thus the diverse effects of pregnancy on UA responsiveness may result from hormonal modulation of G proteins coupled to their specific receptors.

Endotoxemia causing fetal bradycardia during urosepsis

BACKGROUND

Fetal bradycardia is a recognized response to maternal hypothermia associated with hypoglycemia, tocolysis with magnesium sulfate, or urosepsis, and it is thought to be a direct response to the decrease in the maternal core temperature.

CASE

A 25-year-old white woman, gravida 1, para 0, at 31 1/7 weeks' gestation was admitted with a diagnosis of pyelonephritis. The baseline fetal heart rate was 120 beats per minute with accelerations. Within 3 hours of admission, the patient became hypothermic (35.1C) and, concomitantly, the fetal heart rate baseline declined to 90 beats per minute with marked variability. Despite sustained maternal hypothermia, the fetal heart rate baseline rose to 120 beats per minute. It was another 6 hours before the patient's temperature rose above 38.5C. Her urine and blood cultures were positive for Serratia rubidacea infection. The patient delivered a healthy infant at 39 weeks' gestation.

CONCLUSION

Fetal bradycardia in the presence of urosepsis might be due to the release of endotoxin from gram-negative bacteria, triggering production of cardiotoxic cytokines, rather than to maternal hypothermia alone.

Chorion releases a factor that inhibits oxytocin-stimulated myometrial contractility in the pregnant guinea pig

It was postulated that chorion releases a substance necessary for the maintenance of uterine quiescence during pregnancy. A decrease in the release of this substance at the end of the pregnancy would be necessary for normal myometrial activation. This hypothesis was tested by demonstrating the ability of chorion to inhibit oxytocin-stimulated myometrial contractility in vitro. Tissues were obtained from timed pregnant Duncan-Hartley guinea pigs either at pre-term or near-term gestation. Myometrial strips were placed in organ baths for isometric tension measurement and contractions stimulated by oxytocin (10(-8) mol/l). Fetal membranes or conditioned medium from chorion were added directly to the organ bath. Near-term chorion and chorion conditioned-medium decreased oxytocin-stimulated contractile activity to 39% and 49% respectively. Neither pre-term nor near-term amnion reduced oxytocin-stimulated myometrial contractile activity. Relaxation induced by pre-term chorion was greater than near-term chorion (23% and 41% of the oxytocin-induced basal level respectively; P < 0.05). Further, chorion-induced relaxation was independent of the gestational age of the myometrium. Human chorion from a term, not-in-labour woman also inhibited oxytocin-stimulated guinea pig myometrial contractility. It was concluded that the chorion releases a substance or substances that reduce oxytocin-stimulated myometrial contractility and may be involved in the maintenance of uterine quiescence during pregnancy.

Natriuretic peptide-induced relaxation of myometrium from the pregnant guinea pig is not mediated by guanylate cyclase activation

We tested both relaxation and cGMP generation by atrial (ANP), brain (BNP), and C-type natriuretic peptide (CNP) in oxytocin-stimulated myometrium from near-term pregnant guinea pigs to investigate the ability and mechanism of natriuretic peptides to inhibit myometrial contractility. Myometrial strips were contracted by 10(-8) M oxytocin, and relaxation to the cumulative addition (10(-9)-10(-6) M) of the natriuretic peptides measured. Maximal relaxation to BNP was significantly greater than to ANP (52 versus 32% respectively; p < 0.05), whereas CNP failed to produce relaxation. However, the increase in cGMP produced by BNP (10(-7) M) was significantly less than that produced by ANP (10(-7) M) (4.5 versus 7.0 times basal; p < 0.05); CNP did not increase myometrial cGMP. Anantin, a competitive blocker of the guanylate cyclase A receptor, significantly reduced the increase in cGMP produced by ANP and BNP, but had no effect on relaxation induced by either peptide. Rp-8-Br-cGMP, an inhibitor of the cGMP-dependent protein kinase, did not alter BNP-induced relaxation. The atrial natriuretic peptide-fragment 4-23 amide, a natriuretic peptide clearance receptor agonist, failed to inhibit oxytocin-stimulated myometrial contraction. We conclude that natriuretic peptide induced relaxation of oxytocin-stimulated myometrium from the pregnant guinea pig is not mediated by either guanylate cyclase A or B activation, is independent of the cGMP pathway, and does not involve clearance receptor activation. Our results suggest that natriuretic peptide-induced relaxation of pregnant myometrium is mediated via a novel mechanism.

Application of a functional genomics approach to identify differentially expressed genes in human myometrium during pregnancy and labour

The molecular mechanisms regulating uterine relaxation and contraction during pregnancy are poorly understood. In the present study, we used for the first time a functional genomics approach applying gene array technology to identify novel candidate genes involved in the regulation of uterine quiescence and contractility during pregnancy. The purpose of this approach was to obtain a molecular snapshot of the expression profile of gene transcripts as a function of the time dependent process regulating myometrial quiescence. Using this approach, we found several genes whose expression in human myometrium was altered with the onset of labour. For example, the expression of insulin-like growth factor (IGF)-II, calgranulin A and B, and G-protein coupled receptor were decreased while the expression of IGF-binding proteins, Ca(2+)/CaM binding protein kinase C substrate, and angiotensin converting enzyme were increased in the labouring, compared with non-labouring, pregnant myometrium. The differentially-expressed genes include several genes whose roles in myometrial quiescence are yet to be understood, although they have been reported to regulate vascular smooth muscle tone. Our findings illustrate the advantage of a functional genomics approach over a single gene analysis in identifying a large number of novel and potentially important genes mediating uterine smooth muscle contractile activity.

Differential alterations in responsiveness in particulate and soluble guanylate cyclases in pregnant guinea pig myometrium

OBJECTIVE

The mechanism underlying myometrial quiescence during pregnancy is unknown. Our group has previously shown that during pregnancy myometrial cyclic guanosine monophosphate content rises to several hundred times the nonpregnant levels, only to abruptly decline days before the onset of labor. Cyclic guanosine monophosphate plays an integral role in the relaxation of smooth muscle. The aim of this investigation was therefore to determine the effects of pregnancy on both soluble and particulate guanylate cyclase enzymatic activities and messenger ribonucleic acid expressions.

STUDY DESIGN

Myometrium was obtained from randomly cycling adult nonpregnant guinea pigs and near-term (50-60 days' gestation) pregnant guinea pigs of similar chronologic age. Subcellular fractions were prepared by differential ultracentrifugation. Guanylate cyclase activity was determined by the conversion of guanosine triphosphate to cyclic guanosine monophosphate under basal or stimulated conditions in either the soluble guanylate cyclase or particulate guanylate cyclase fraction. A nitric oxide donor, S-nitroso- N-penacillamine, was used to activate soluble guanylate cyclase (n = 10 animals in each group). Several natriuretic peptides (atrial natriuretic peptide, brain natriuretic peptide, and C-type natriuretic peptide) and uroguanylin were used to stimulate the different particulate guanylate cyclase isoforms guanylate cyclase A, guanylate cyclase B, and guanylate cyclase C, respectively, in pregnant (n = 8) and nonpregnant (n = 6) animals. Cyclic guanosine monophosphate content was measured by radioimmunoassay, and enzymatic activity was expressed as picomoles of cyclic guanosine monophosphate per milligram of protein per minute. Total guanylate cyclase represented the sum of soluble guanylate cyclase and particulate guanylate cyclase activities for a tissue. To investigate whether the observed changes in guanylate cyclase activity were paralleled by changes in receptor expression, messenger ribonucleic acid levels of the genes for guanylate cyclase A and guanylate cyclase B isoforms were quantified by ribonuclease protection assay (n = 5 animals in each group).

RESULTS

Under basal conditions particulate guanylate cyclase represented 78% (nonpregnant state) to 88% (during pregnancy) of the total guanylate cyclase activity in the guinea pig myometrium. Pregnancy further reduced myometrial soluble guanylate cyclase (both basal and stimulated by nitric oxide) relative to the nonpregnant state. Pregnancy selectively increased atrial natriuretic peptide-stimulated particulate guanylate cyclase activity (attributed to guanylate cyclase A), although it did not change basal myometrial particulate guanylate cyclase activity in general. Guanylate cyclase B (particulate guanylate cyclase stimulated by C-type natriuretic peptide) and guanylate cyclase C (particulate guanylate cyclase stimulated by uroguanylin) activities were unaltered by pregnancy. The selective increase in responsiveness of particulate guanylate cyclase to atrial natriuretic peptide during pregnancy was not paralleled by an increased in level of messenger ribonucleic acid for the gene for guanylate cyclase A.

CONCLUSION

Pregnancy reduced the in vitro responsiveness of the myometrial soluble guanylate cyclase to nitric oxide while increasing the responsiveness of the particulate isoform to atrial natriuretic peptide and brain natriuretic peptide through a mechanism independent of any change in receptor expression.

Chronic hypoxia increases the NO contribution of acetylcholine vasodilation of the fetal guinea pig heart

To investigate the effect of chronic hypoxia (HPX) on vasodilation of the fetal heart, we exposed pregnant guinea pigs to room air or 12% O(2) for 4, 7, or 10 days. We excised hearts from anesthetized fetuses (60 +/- 3 days; 65-day gestation = term) and measured changes in both the coronary artery pressure of the isolated constant-flow preparation and endothelial nitric oxide synthase (eNOS) mRNA of fetal ventricles. Dilator responses to cumulative addition (10(-9)-10(-5) M) of acetylcholine and sodium nitroprusside in prostaglandin F(2alpha) (5 x 10(-6) M)-constricted hearts were similar among normoxia (NMX), 4-, 7-, and 10-day HPX (control). Nitro-L-arginine (L-NA, 10(-4)M), a NOS inhibitor, inhibited maximal acetylcholine dilation of hearts exposed to 10-day HPX greater than NMX, 4-, and 7-day HPX. Hypoxia (after 7 and 10 days) increased eNOS mRNA of fetal ventricles compared with NMX and 4-day HPX. 4-Aminopyridine (3 mM), a voltage-dependent K(+)-channel inhibitor, inhibited acetylcholine- but not sodium nitroprusside-induced dilation of NMX and 10-day HPX hearts to a similar magnitude. Glibenclamide (10(-5) M), an ATP-sensitive K(+)-channel inhibitor, had no effect on vasodilation. We conclude that chronic HPX increases the contribution of NO but does not alter K(+)-channel activation in response to acetylcholine-stimulated coronary dilation. Thus increases in NO production via upregulation of eNOS gene expression may be an adaptive response to chronic HPX in the fetal coronary circulation.

Coronary artery blood flow visualization signifies hemodynamic deterioration in growth-restricted fetuses

OBJECTIVE

To determine the relationship between fetal coronary blood flow (CBF) visualization in intrauterine growth restriction (IUGR), longitudinal changes in arterial and venous flow velocity waveforms and perinatal outcome.

METHODS

A total of 48 IUGR fetuses (abdominal circumference below the 5th percentile for gestational age) with absent or reversed umbilical artery (UA) end-diastolic velocity (AREDV) were examined longitudinally by echocardiography attempting CBF visualization at each examination. Doppler evaluation of the middle cerebral artery, inferior vena cava (IVC), ductus venosus (DV) and umbilical vein (UV) was performed at each examination. Doppler measurements were correct for gestational age by conversion into Z-scores (delta-indices). Doppler results and outcome from fetuses in which CBF was visualized (group 1, n = 20) and those in which CBF was never visualized (group 2, n = 28) were compared. Outcome parameters analyzed included Apgar scores, cord arterial blood gases, perinatal mortality, respiratory distress, bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis and postpartum circulatory failure requiring pressor support.

RESULTS

There was no difference in Doppler indices between groups at study entry. CBF visualization coincides with a significant increase of UA-, IVC- and DV delta-indices. The greatest rate of change was observed for indices in the ductus venosus which occurred in the 24 h preceding CBF visualization. Group 1 fetuses required earlier delivery (median 27 + 4, vs. median 30 + 0), had lower birthweight (682 +/- 305 g vs. 936 +/- 416 g), lower cord pH (7.21 +/- 0.1 vs. 7.27 +/- 0.06) and cord pO2 (13 +/- 4.5 vs. 24.1 +/- 13.5 mmHg) compared to group 2 (all values P < 0.05). Mortality was similar (group 1 = 6/20, 30%; group 2 = 6/28, 21.4%).

CONCLUSIONS

In IUGR, fetuses with AREDV and centralization are at high risk for hypoxemia, acidemia and adverse outcome. CBF visualization coincides with deteriorating venous flows. Operator dependence of CBF visualization and the strong association with abnormal venous flow stresses the importance of venous Doppler surveillance in these fetuses.

Relationship between arterial and venous Doppler and perinatal outcome in fetal growth restriction

OBJECTIVE

The aim of this investigation was to assess the relationship between abnormal arterial and venous Doppler findings and perinatal outcome in fetuses with intrauterine growth restriction (IUGR).

METHODS

Doppler velocimetry of the umbilical artery (UA), middle cerebral artery (MCA), inferior vena cava (IVC), ductus venosus (DV) and free umbilical vein was performed in 121 IUGR fetuses with a UA pulsatility index (PI) > 2 SD above the gestational age mean and subsequent birth weight < 10th centile for gestational age. Groups based on the last Doppler exam were: 1 = abnormal UA-PI only (n = 42, 34.7%), 2 = MCA-PI > 2 SD below the gestational age mean (= 'brain sparing') in addition to abnormal UA-PI (n = 29, 24.0%), 3 = DV or IVC peak velocity index (PVIV) > 2 SD above the gestational age mean and/or pulsatile UV flow (n = 50, 41.3%). Z-scores (delta indices) were calculated for Doppler indices. Perinatal mortality, respiratory distress (RDS), bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), circulatory failure and umbilical artery blood gases were recorded.

RESULTS

Absence or reversal of umbilical artery end-diastolic flow was observed in 4 (9.5%) of fetuses in group 1, 10 (34.5%) fetuses in group 2 and 41 (82%) fetuses in group 3. A low middle cerebral artery pulsatility index was found in 39 (78%) fetuses in group 3. Multiple regression analysis with gestational age at delivery, delta indices and cord artery blood gas as independent parameters and individual perinatal outcomes as dependent variables was performed. In this analysis the association was strongest with gestational age for each complication. There were no significant differences in Apgar scores between groups. At delivery, 'brain sparing' was associated with hypoxemia and abnormal venous flows with acidemia. Perinatal mortality was highest in group 3 and stillbirth was only observed when venous flow was abnormal. All postpartum complications were more frequent in fetuses with abnormal venous flows. The only statistically significant relation between Doppler indices and outcome was the association between abnormal ductus venosus flow and fetal death (r2 = 0.24, P < 0.05).

CONCLUSION

Growth restricted fetuses with abnormal venous flow have worse perinatal outcome compared to those where flow abnormality is confined to the umbilical or middle cerebral artery. In fetuses with low middle cerebral artery pulsatility, venous Doppler allows detection of further deterioration. While abnormal venous flows can be significantly associated with fetal demise, gestational age at delivery significantly impacts on all short-term outcomes.

Molecular mechanism of cGMP-mediated smooth muscle relaxation

Contraction and relaxation of smooth muscle is a tightly regulated process involving numerous endogenous substances and their intracellular second messengers. We examine the key role of cyclic guanosine monophosphate (cGMP) in mediating smooth muscle relaxation. We briefly review the current art regarding cGMP generation and degradation, while focusing on the recent identification of the molecular mechanisms underlying cGMP-mediated smooth muscle relaxation. cGMP-induced SM relaxation is mediated mainly by cGMP-dependent protein kinase activation. It involves several molecular events culminating in a reduction in intracellular Ca(2+) concentration and a decrease in the sensitivity of the contractile system to Ca(2+). We propose that the cGMP-induced decrease in Ca(2+) sensitivity is a strategic way to achieve "active relaxation" of the smooth muscle. In summary, we present compelling evidence supporting a key role for cGMP as a mediator of smooth muscle relaxation in physiological and pharmacological settings.

Absent umbilical artery end-diastolic velocity in growth-restricted fetuses: a risk factor for neonatal thrombocytopenia

OBJECTIVE

To examine the relationship between umbilical artery (UA) end-diastolic flow and neonatal thrombocytopenia.

METHODS

We prospectively examined 115 anatomically normal single fetuses with UA pulsatility indices more than two standard deviations above the gestational age mean and subsequent birth weights below the tenth percentile. Peripheral neonatal platelet counts in fetuses with positive UA end-diastolic velocity were compared with those of fetuses with absent or reversed UA end-diastolic velocity.

RESULTS

Sixty-seven fetuses (58.3%) had positive UA end-diastolic velocity and 48 (41.7%) had absent or reversed UA end-diastolic velocity. Three neonates in the positive-flow group and 22 neonates in the absent- or reversed-flow group had platelet counts of less than 100, 000/mm(3) (relative risk 10.2; 95% confidence interval; 3.2, 32.3; P <.001). Absent or reversed end-diastolic velocity had a sensitivity of 88%, specificity of 71%, positive predictive value of 46%, and negative predictive value of 96% for predicting neonatal thrombocytopenia. Neonates with absent or reversed flow also had lower median platelet counts (101,500/mm(3) versus 208,000/mm(3), P <.001), hemoglobin levels (15.1 versus 16.4 g/dL, P <.01), and hematocrits (47.6 versus 51.1%, P <.05), as well as higher nucleated red blood cell counts (191 versus 15 per 100 white blood cells, P <. 001).

CONCLUSION

Absent or reversed UA end-diastolic velocity in growth-restricted fetuses is associated with a statistically significant increase in risk of neonatal thrombocytopenia.

Chronic 17beta-estradiol replacement increases nitric oxide-mediated vasodilation of guinea pig coronary microcirculation

BACKGROUND

Estrogen is cardioprotective of the coronary circulation by mechanisms incompletely understood. This study determined the effect of chronic 17beta-estradiol replacement on dilator responses to acetylcholine and sodium nitroprusside of the isolated coronary microcirculation.

METHODS AND RESULTS

Adult female guinea pigs were ovariectomized, and a 21-day-release pellet containing 0.0, 0.1, 0.25, 0.5, or 1.0 mg 17beta-estradiol was implanted subcutaneously. Serum estradiol concentrations ranged from 3.9 to 74.9 pg/mL, increasing with the dose of estradiol. After 19 to 20 days, the animals were euthanized, and their hearts were removed and perfused with buffer at constant flow on an isolated heart apparatus. Both perfusion pressure and contractile force were measured in prostaglandin F(2alpha)-constricted hearts. Vasodilation to the cumulative addition of the endothelium-dependent agonist acetylcholine (10(-9) to 10(-5) mol/L) and the nitric oxide (NO) donor sodium nitroprusside (10(-9) to 10(-5) mol/L) was measured before and after NO synthesis inhibition by nitro-L-arginine (LNA, 10(-4) mol/L). Baseline coronary resistance was unaltered by estradiol, although LNA increased resistance in estradiol-treated hearts more than in ovariectomized controls. Chronic 17beta-estradiol increased sensitivity (measured by -log EC(50) values) but not maximal response to acetylcholine compared with ovariectomized controls. Differences were abolished by LNA at all doses of estradiol. Sodium nitroprusside-induced dilation was unaffected by estradiol replacement.

CONCLUSIONS

Chronic 17beta-estradiol replacement, at doses producing hormone levels within the physiological range, enhances dilator sensitivity of the coronary microcirculation through enhanced NO production by the endothelium, independent of changes in NO sensitivity of the vascular smooth muscle. Thus, estradiol enhances NO production as a protective mechanism of the coronary microcirculation.

Association of fetal and maternal carboxyhemoglobin levels in normal and Rh-alloimmune pregnancies

OBJECTIVE

To compare paired antepartum fetal/maternal COHb ratios in whole blood from control and alloimmunized pregnancies and to examine the relationships between fetal and maternal COHb.

METHODS

COHb levels were measured in paired fetal and maternal blood samples obtained at cordocentesis in 47 control and 16 Rh-alloimmunized pregnancies. COHb was determined by gas chromatography. Results were analyzed by t-test, regression and analysis of covariance.

RESULTS

Although fetal/maternal COHb ratios for control and alloimmunized pregnancies were not statistically significantly different, i.e. 1. 11+/-0.04 and 1.26+/-0.09, respectively (P=0.09), fetal COHb levels were higher in Rh-alloimmunized fetuses (P=0.0002). Fetal COHb levels were also higher than paired maternal levels among the alloimmunized group (P=0.011), but not among the control group (1. 04+/-0.04, P=ns). In univariate regression analysis, fetal and maternal COHb levels were significantly correlated with one another in both control (r=0.52, P=0.0002) and alloimmunized pregnancy groups (r=0.52, P=0.05). Comparison of the slopes of the fetal versus maternal COHb plots for the two groups showed a significant difference (P=0.02), with the alloimmunized group having the steeper slope.

CONCLUSION

Differences in the antepartum fetal-maternal COHb relationships in control and alloimmunized groups likely reflect increased endogenous CO production among alloimmunized fetuses as a result of pathologic hemolysis.

Reduction-oxidation (redox) state regulation of matrix metalloproteinase activity in human fetal membranes

OBJECTIVE

The mechanisms underlying membrane rupture at term and preterm are obscure. Collagenolytic activity of matrix metalloproteinases in amniochorionic membranes increases during spontaneous term and preterm labor associated with intra-amniotic infection. We sought to test the hypothesis that reduction-oxidation homeostasis, which is altered in inflammatory states, directly regulates amniochorionic matrix metalloproteinases.

STUDY DESIGN

Membranes were collected from 7 patients undergoing elective cesarean delivery at term, rinsed thoroughly, and immediately incubated in phosphate-buffered sodium chloride solution at 37 degrees C for 24 hours. Matrix metalloproteinase activity in the culture medium was assayed by substrate-gel electrophoresis and normalized against the dry weight of the tissue incubated. Superoxide anions were generated in the presence of membranes by a xanthine (2 mmol/L) and xanthine oxidase (20 mU/mL) mixture and monitored by reduction of ferri-cytochrome c to ferro-cytochrome c. Incubations were performed in the presence of xanthine alone, a xanthine-xanthine oxidase mixture, superoxide dismutase (500 U/mL), a xanthine-xanthine oxidase-superoxide dismutase mixture, nitro-L-arginine (a nitric oxide synthase inhibitor, 1 mmol/L), xanthine-xanthine oxidase-nitro-L-arginine, S-nitroso-N -acetylpenicillamine (a nitric oxide donor, 10 mmol/L), xanthine-xanthine oxidase-S-nitroso-N -acetylpenicillamine, N -acetylcysteine (a thiol-containing antioxidant, 0.1, 1, or 10 mmol/L), lipopolysaccharide (100 ng/mL), or lipopolysaccharide-N -acetylcysteine. Intracellular generation of superoxide anions was monitored by the reduction of nitroblue tetrazolium to formazan.

RESULTS

Basal matrix metalloproteinase 9 and matrix metalloproteinase 2 levels were detected in all samples. Superoxide anions significantly increased matrix metalloproteinase 9 activity but did not increase matrix metalloproteinase 2 activity, which effect was reversed by the addition of superoxide dismutase. N-acetylcysteine reduced basal activity of both matrix metalloproteinase 9 and matrix metalloproteinase 2 to 20%. Importantly, N-acetylcysteine completely inhibited intracellular formazan formation in cultured membranes both in the absence and in the presence of lipopolysaccharide. Neither nitric oxide synthase inhibition nor the nitric oxide donor S-nitroso-N -acetylpenicillamine had any effect on fetal membrane matrix metalloproteinase activity.

CONCLUSION

Matrix metalloproteinase activity in human fetal membranes is reduction-oxidation (redox)-regulated. Matrix metalloproteinase 9 activity in human fetal membranes is directly increased by superoxide anion, a byproduct of macrophages and neutrophils. Neither nitric oxide donors nor nitric oxide synthase inhibitors significantly affect matrix metalloproteinase activity in human fetal membranes. The glutathione precursor N-acetylcysteine dramatically inhibits amniochorionic matrix metalloproteinase activity in addition to inhibiting intrinsic superoxide generation within the tissue. Thus thiol-reducing agents, such as N-acetylcysteine, may be beneficial in preventing preterm premature rupture of the membranes.

Umbilical artery doppler screening for detection of the small fetus in need of antepartum surveillance

OBJECTIVE

Our goal was to test the hypothesis that umbilical artery Doppler velocimetry identifies fetuses who are small for gestational age and in need of antenatal surveillance.

STUDY DESIGN

Three hundred eight fetuses with either an ultrasonographic weight estimate <10th percentile for gestational age or an abdominal circumference <2.5th percentile for gestational age or both of these had an umbilical artery Doppler measurement of the systolic/diastolic ratio. A systolic/diastolic ratio >90th percentile for gestation was considered abnormal. The incidences of a birth weight <10th percentile, fetal distress, and metabolic acidemia were recorded for both groups (normal vs abnormal umbilical artery Doppler).

RESULTS

Only the umbilical artery systolic/diastolic ratio predicted perinatal outcome in the group of fetuses who were presumed to be small for gestational age. Those 138 fetuses with elevated umbilical artery systolic/diastolic ratios had lower umbilical artery and vein pH values at birth (artery, 7.23 +/- 0.08 vs 7.25 +/- 0.1; P <.02; vein, 7.31 +/- 0.01 vs 7.34 +/- 0.09; P =.01), an increased likelihood of fetal distress consistent with chronic hypoxemia (26.3% vs 8.6%; P <.0001), more admissions to the neonatal intensive care unit (40.7% vs 30.7%; P <.005), and a higher incidence of respiratory distress (66% vs 27.3%; P <.03). However, it is important that no fetus with a normal Doppler flow measurement was delivered with a metabolic acidemia associated with chronic hypoxemia. Further, the likelihood of a false-positive diagnosis of intrauterine growth restriction was increased in the group with a normal umbilical artery Doppler resistance.

CONCLUSION

Antenatal surveillance may be unnecessary in fetuses with suspected intrauterine growth restriction if the umbilical artery systolic/diastolic ratio and amniotic fluid volume are normal, because the complications that occur are intrapartum. If these findings are confirmed in prospective trials, the cost implication of reducing the number of antenatal surveillance tests administered in this group of patients is great.

Increased nitric oxide synthesis is not involved in delayed cerebral energy failure following focal hypoxic-ischemic injury to the developing brain

This study addressed the hypothesis that the delayed impairment in cerebral energy metabolism that develops 10-24 h after transient hypoxia-ischemia in the developing brain is mediated by induction of increased nitric oxide synthesis. Four groups of 14-d-old Wistar rat pups were studied. Group 1 was subjected to unilateral carotid artery ligation and hypoxia followed immediately by treatment with the nitric oxide synthase (NOS) inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg). Group 2 underwent hypoxia-ischemia but received saline vehicle. Group 3 received L-NAME without hypoxia-ischemia, and group 4, saline vehicle alone. At defined times after insult, the expression of neuronal and inducible NOS were determined and calcium-dependent and -independent NOS activities measured. Cerebral energy metabolism was observed using 31P magnetic resonance spectroscopy. At 48 h after insult, the expression of inducible NOS increased, whereas neuronal NOS at 24 h decreased on the infarcted side. Calcium-dependent NOS activity was higher than calcium-independent NOS activity, but did not increase within 36 h after insult, and was significantly inhibited by the administration of L-NAME. However, L-NAME did not prevent delayed impairment of cerebral energy metabolism or ameliorate infarct size. These results suggest that the delayed decline in cerebral energy metabolism after hypoxia-ischemia in the 14-d-old rat brain is not mediated by increased nitric oxide synthesis.

Effects of acute and chronic hypoxia on nitric oxide-mediated relaxation of fetal guinea pig arteries

OBJECTIVE

These studies tested whether fetal artery reactivity is sensitive to both acute changes in oxygen levels (in vitro) and chronic changes (in utero).

STUDY DESIGN

Pregnant guinea pigs near term were exposed to either normoxia or hypoxia (12% oxygen) for 4 or 7 days. The effect of decreasing PO (2 ) in vitro (acute hypoxia) on relaxation in response to acetylcholine, A23187, sodium nitroprusside, and 8-bromo-cyclic guanosine monophosphate was measured in isolated carotid arteries from normoxic fetuses. In separate experiments relaxation in response to acetylcholine and sodium nitroprusside of endothelially intact and denuded fetal arteries from fetuses exposed to normoxic conditions and long-term (4 and 7 days) hypoxic conditions was measured in the presence and absence of nitro-L -arginine (10(-4) mol/L).

RESULTS

Acute hypoxia inhibited endothelium-dependent relaxation in response to acetylcholine and A23187, increased sensitivity to sodium nitroprusside, but had no effect on relaxation in response to 8-bromo-cyclic guanosine monophosphate. Chronic hypoxia (4 but not 7 days) inhibited maximal relaxation of arteries in response to acetylcholine but not relaxation of arteries in response to sodium nitroprusside with respect to relaxation seen in arteries from normoxic fetuses. Nitro-L -arginine attenuated the differences between normoxic and hypoxic fetuses in acetylcholine response.

CONCLUSION

Hypoxia may alter relaxation of fetal arteries by decreasing the availability of oxygen for nitric oxide production and causing vascular adaptations related to altered nitric oxide release.

Neonatal nucleated red blood cell counts in growth-restricted fetuses: relationship to arterial and venous Doppler studies

OBJECTIVE

Elevated nucleated red blood cell count in neonatal blood and Doppler-detected circulatory decompensation in fetuses with intrauterine growth restriction are associated with hypoxemia. We sought to determine the relationship between the nucleated red blood cell count at birth and the circulatory status of fetuses with intrauterine growth restriction.

STUDY DESIGN

Eighty-four fetuses with elevated umbilical artery pulsatility index values >2 SD above the gestational age mean and a subsequent birth weight <10th percentile were examined serially. Umbilical and middle cerebral artery pulsatility index, inferior vena cava and ductus venosus peak velocity index, and flow pattern in the umbilical vein (umbilical vein constant vs pulsatile) were recorded. Fetuses were grouped as follows, on the basis of the last examination before delivery: 1, elevated umbilical artery pulsatility index only; 2, middle cerebral artery pulsatility index >2 SD below the gestational age mean in addition to abnormal umbilical artery pulsatility index; 3, either peak velocity index >2 SD above the gestational age mean in the inferior vena cava and ductus venosus or pulsatile flow in the umbilical vein, or both. Nucleated red blood cells per 100 white blood cells were ascertained in a peripheral blood sample obtained within 1 hour of delivery with daily follow-up samples until the nucleated red blood cell count was <5/100 white blood cells.

RESULTS

Groups 2 (median 38.5, range 1-273) and 3 (median 145, range 2-3180) had higher nucleated red blood cell counts than group 1 (median 8.5, range 1-270) (P <.05 and P <.005, respectively). The persistence of the nucleated red blood cell count elevation was also longer in groups 3 (median 4 days, range 1-19 days) and 2 (median 2. 5 days, range 1-7 days) than in group 1 (median 1 day, range 1-8 days). Neonates in group 3 also had lower platelet count, hemoglobin value, hematocrit value, and white blood cell count. The umbilical cord artery bicarbonate level was the strongest independent determinant of the peak nucleated red blood cell count and persistence of nucleated red blood cell elevation (r (2) = 0.27, P <. 001 and r (2) = 0.47, P <.0001).

CONCLUSION

Increasing abnormality of arterial and venous flows in fetuses with intrauterine growth restriction is associated with increasing nucleated red blood cell count at birth. Metabolic acidemia rather than altered PO (2 ) associated with this circulatory state appears to be the main determinant of the rise in nucleated red blood cells.

Temporal expression of inducible nitric oxide synthase in mouse and human placenta

The aim of this study is to investigate the changes in expression and activity of inducible nitric oxide synthase (iNOS) in the developing murine embryo and mouse and human placenta. Using reverse transcription-polymerase chain reaction (RT-PCR), Northern blotting, and in-situ hybridization (ISH) we identified iNOS mRNA in mouse placenta at 9.5, 12, 14, 16, 18 and 20 days post coitum. Northern blot analysis demonstrated that the quantity of murine iNOS transcript was expressed at a stable level between days 12-20 although the level of calcium-independent NOS activity declined with advancing gestation. RT-PCR detected iNOS-specific mRNA in murine embryonic stem cells, but not in embryos at later stages (4-cell or blastocyst). ISH failed to show iNOS-specific mRNA in either murine placenta or the underlying myometrium on day 7, but did so in the trophoblast by day 9.5. Later in gestation, extensive labelling was observed in both spongiotrophoblast and trophoblast giant cells. iNOS mRNA was also detected both in immature human placentae (16-18 weeks) and at term, predominantly in syncytiotrophoblasts and placental artery smooth muscle. In conclusion, iNOS is constitutively expressed in mouse and human placenta at a time and in a location that suggests a role in placentation.

Effect of chronic hypoxemia on the regulation of nitric-oxide synthase in the fetal sheep brain

We tested the hypothesis that chronic hypoxemia modulates NO production of the fetal brain by altering its gene and protein expression. Chronically instrumented preterm fetal sheep were made hypoxemic by placental embolization for 21 days. Fetal oxygen content was measured to determine the level of hypoxemia. The expression of both eNOS and nNOS proteins and mRNA and enzyme activities of fetal sheep cerebrum were measured and compared between normoxic and hypoxemic animals. Our results show that in utero hypoxemia downregulates both Ca2+ dependent NOS activity and expression of eNOS protein and mRNA in the fetal sheep brain. In contrast, hypoxemia increased nNOS protein and mRNA levels in the cerebrum. This suggests that chronic hypoxemia has an opposing effect on eNOS and nNOS gene regulation. We propose that increased nNOS activity during chronic hypoxemia may excessively stimulate the neurons and contribute to fetal brain injury. On the other hand, downregulation of eNOS activity and expression may compromise the neuroprotective effect of eNOS and, therefore, further exacerbate brain injury.

Fetal coronary and cerebral blood flow in acute fetomaternal hemorrhage

A fetal heart rate tracing with absent variation and a sinusoidal pattern led to the diagnosis of acute fetomaternal hemorrhage at 29 + 2 weeks' gestation. The middle cerebral artery had increased peak blood flow velocity with reversed end-diastolic flow. Fetal coronary arteries visualized by color-coded and pulsed wave Doppler sonography showed slight decrease of time-averaged maximum velocities after oxygen administration, while cerebral flows remained unchanged. After administration of 50 ml blood (pre-transfusion hematocrit < 11%) the middle cerebral artery flow normalized and coronary artery velocities decreased further until coronary blood flow could no longer be visualized within 30 min of the transfusion (post-transfusion hematocrit 27%). Evidence of successful fetal resuscitation also included normalization of the fetal heart rate tracing and resumption of fetal activity (biophysical profile score 8/10). This was also observed after a second transfusion of 38 ml blood. Deterioration from repeated fetomaternal hemorrhage led to delivery of a severely anemic neonate (cord hematocrit 7%) by Cesarean section. Postnatally, a single seizure, moderate severity respiratory distress syndrome and grade III intraventricular hemorrhage were noted. Increased peak blood flow velocity with reversed end-diastolic flow may be observed in the middle cerebral artery of fetuses with acute anemia. Correction of this phenomenon with transfusion suggests that hypovolemia and low blood viscosity are major contributing factors. Furthermore, decreasing coronary artery blood flow velocities with supplemental oxygen and blood replacement confirm functional autoregulation of the fetal coronary circulation. Observation of these acute flow changes during fetal surveillance warrants investigation for a potentially serious underlying condition.

The optimal route of delivery for fetal meningomyelocele

OBJECTIVE

It has been proposed that cesarean section improves the long-term neurologic outcome of children with meningomyelocele. On the basis of this belief, a trial of labor is not offered in many centers. We hypothesized that there is no difference in immediate or long-term outcome by route of delivery for the fetus with meningomyelocele delivered in a tertiary care center.

STUDY DESIGN

All fetuses (n = 60) with meningomyelocele delivered at the University of Iowa Hospitals and Clinics between 1971 and 1995 were analyzed. Thirty-six cases were available for long-term follow-up. Motor, sensory, and anatomic levels were converted to a numeric scale. Variables were compared by one-way analysis of variance, chi2 analysis, and Fisher's exact test with significance at P < .05.

RESULTS

There were no significant differences by route of delivery for gestational age of delivery, birth weight, meningomyelocele size, or neonatal mortality (vaginal: 1/22 = 4.5%, cesarean section: 2/17 = 11.8%, P = .82). An antenatal diagnosis was made with similar frequency in the two groups (vaginal: 15/21 = 71.4%, cesarean section: 13/15 = 86.7%). In addition, the length of long-term follow-up was similar (vaginal: 54.7 +/- 11.1 months, cesarean section: 33.7 +/- 8.6 months). There was no difference in long-term neurologic outcome as determined by the change in motor level, the change in sensory level, or when comparing the final motor level with the anatomic level.

CONCLUSIONS

This study was unable to detect differences between either immediate or long-term outcome for the infant with isolated meningomyelocele when stratified by route of delivery. A multicenter randomized trial should be required before the acceptance of cesarean section as the optimal route of delivery for the fetus with meningomyelocele.

Detection of intrauterine viral infection using the polymerase chain reaction

Intrauterine viral infection commonly presents as nonimmune hydrops fetalis or intrauterine growth restriction. Cytomegalovirus (CMV) and parvovirus are commonly recognized causes of fetal infection using serology and cultures. We used the polymerase chain reaction (PCR) to evaluate the frequency of fetal viral infection and the associated clinical course and outcome. Specimens (amniotic fluid, fetal blood, pleural fluid, tissue) from 303 abnormal pregnancies at risk for viral infection and 154 controls were analyzed using primers for CMV, herpes simplex virus, parvovirus B19, adenovirus, enterovirus, Epstein-Barr virus, and respiratory syncytial virus. Viral genome was detected in 144/371 samples (39%) or 124/303 patients (41%), with adenovirus (n = 74 patients; 24%), CMV (n = 30 patients; 10%), and enterovirus (n = 22 patients; 7%) most common. Only 4/154 (2.6%), unaffected control patients' samples were PCR positive. We conclude that diagnosis of fetal viral infection by PCR is common in abnormal pregnancies. Adenovirus and enterovirus may cause fetal infection that have been previously unrecognized.

Umbilical venous pressure is unaltered by severe, early-onset growth restriction

OBJECTIVE

To determine whether severe, early-onset intrauterine growth restriction (IUGR) is associated with abnormal umbilical venous pressure (UVP) secondary to increased placental impedance.

METHODS

42 singleton fetuses underwent fetal blood sampling from the umbilical vein during evaluation for severe, early-onset IUGR (diagnosed < 32 weeks or symmetrical IUGR diagnosed at any time in gestation). IUGR was confirmed at delivery. The UVP was measured with a solid-state transducer and corrected for amniotic fluid pressure. The ultimate cause of IUGR assigned was based on the antenatal laboratory and postnatal findings. Seven fetuses had a chromosome abnormality, 4 congenital viral infection, 8 miscellaneous causes and 23, by exclusion, uteroplacental (UP) dysfunction. Procedures complicated by fetal bradycardia were excluded because bradycardia raises the UVP.

RESULTS

The mean gestation was 31.4 weeks (range 23-38). The umbilical artery resistance index (UA RI) was significantly higher in fetuses with IUGR secondary to either UP dysfunction or a chromosome abnormality compared to the remaining categories of IUGR. The UVP fell outside the 95% confidence interval in only 3 fetuses - 2 with aneuploidy (a 1:7 translocation with a normal UA RI and a mosaic trisomy 21), and 1 with UP dysfunction. The UVP rose with advancing gestation independent of the underlying cause of IUGR. There was an inverse relationship between UVP and the UA RI independent of gestation (r2 = 0.08, p < 0.05). There was an inverse relationship between the UA RI and both the UV pH and PO2 in the fetuses with UP dysfunction. However, there was no relationship between the UVP and either UVpH, UVPCO2, or UVpO2.

CONCLUSIONS

These findings indicate that placental impedance has little clinically relevant impact on the UVP.

Nitric oxide and pregnancy

We have hypothesized that an alteration in the production of endothelium-dependent factors by sex hormones is a potential unifying mechanism for both the decreased arterial contractility and the redistribution of cardiac output characteristic of normal pregnancy. Thus, the effect of pregnancy/ estradiol on any one vascular bed will reflect the number and distribution of estrogen receptors. In this article, we review what is known about the effects of pregnancy and estrogen on nitric oxide synthase. Pregnancy increases Ca(2+)-dependent NOS activity early in gestation. The timing of the increase parallels the increase in plasma estradiol concentration. The increase in maternal brain NOS during pregnancy is blocked by tamoxifen. cGMP content increases along a similar time course in most but not all tissues. The changes in cGMP more closely approximate the changes in blood flow during pregnancy. This suggests that multiple elements of the NO:cGMP pathway are altered by pregnancy. It also shows that cGMP content cannot always be used as a surrogate for NOS activity. Estradiol, but not progesterone or testosterone, increases CA(2+)-dependent NOS activity. NO accounts for some, but not all of the pregnancy-associated changes in maternal arterial contractile response. It is not involved in uterine quiescence. Nitric oxide synthase is developmentally regulated in the fetus and is likely important in regulating the distribution of fetal blood flow.

Encapsulated beta-islet cells as a bioartificial pancreas to treat insulin-dependent diabetes during pregnancy

OBJECTIVE

Our purpose was to determine the effectiveness of the bioartificial pancreas technique in correcting (1) maternal carbohydrate metabolism and (2) fetal malformation rates in a pregnant diabetic animal model.

STUDY DESIGN

Insulin secretion from encapsulated rat islets cultured in the presence of homologous rat prolactin was determined and compared with that of controls. Streptozotocin-induced diabetic Balb/c mice were then transplanted with rat islet cells encapsulated within alginate microbeads and were then bred. Blood glucose determinations were made after transplantation and throughout gestation. Pups were delivered by cesarean section on day 19 of gestation. Outcome parameters from the transplanted study animals were compared with those of nondiabetic controls and untreated diabetic animals.

RESULTS

Insulin secretion was increased twofold in encapsulated rat islets exposed to prolactin compared with control values. Throughout gestation maternal weights and blood, glucose levels of transplanted animals were similar to those of nondiabetic controls. A fetal malformation rate of only 1.4% was observed in the pups from transplanted animals.

CONCLUSIONS

Transplanted encapsulated islets are capable of normalizing maternal carbohydrate metabolism in a pregnant diabetic animal model. This therapy, if instituted before conception, also appears to eliminate the increase in fetal malformations seen in diabetic pregnancies.

Polymerase chain reaction determination of RhC, Rhc, and RhE blood types: an evaluation of accuracy and clinical utility

OBJECTIVE

Polymerase chain reaction amplification of a portion of the RhC/c/E/e gene could lead to a rapid, accurate determination of fetal RhC/c/E status. The purpose of this study was to evaluate the accuracy of this technique by testing for the first time a large number of deoxyribonucleic acid samples derived from individuals whose RhC/c/E status was established by standard serologic methods. We also evaluated the potential clinical utility of polymerase chain reaction to ascertain fetal antigen status.

STUDY DESIGN

Samples were obtained from Centre d'Etude du Polymorphisme Humain families used for studies of genetic variation (n = 655). Deoxyribonucleic acid was extracted by standard techniques. With few modifications, published primers and reaction conditions were used. Samples were digested with restriction enzymes yielding characteristic electrophoresis patterns for RhC/c/E. Clinical utility was assessed by review of all patients evaluated for erythrocyte sensitization.

RESULTS

RhC-positive (n = 479), RhC-negative (n = 176), Rhc-positive (n = 524), Rhc-negative (n = 131), RhE-positive (n = 131) and RhE-negative (n = 524) samples were evaluated. The sensitivity of RhC/ c and E typing by polymerase chain reaction was 98.3%, 98.1%, and 96.9%, respectively. The specificity of polymerase chain reaction for identifying the RhC/c/E antigens was 91.5%, 94.7%, and 99.2%, respectively.

CONCLUSIONS

Although it would appear that use of polymerase chain reaction to establish RhC/c/E type could aid in evaluation of RhC/c/E sensitization, we are concerned about the instances of antigen-positive individuals characterized as antigen negative. Further study is necessary to determine if this reflects a polymorphism, mutation, a data coding error, or a combination. The Centre d'Etude du Polymorphisme Humain database is known to contain such errors at a rate that may surpass the error rate of our testing. A second molecular technique could be used to achieve better accuracy in the ascertainment of Rh C/c/E type. On the basis of a review of our patient population, molecular deoxyribonucleic acid techniques now available could aid the management of erythrocyte sensitization in pregnancy in > 96% of cases.

The elusive search for fetal infection. Changing the gold standards

Two percent to four percent of all newborns have a major structural malformation of which only a small percentage can be explained by either aneuploidy or a single-gene disorder. No other mammal has a similar reproductive problem. It is the suggestion that previously unrecognized viral infection accounts for a large percentage of these abnormalities by interfering with appropriate embryonic cell migration, reducing hyperplasia, or damaging the precursor structure by means of an inflammatory mechanism.

Long-term estradiol replacement decreases contractility of guinea pig coronary arteries to the thromboxane mimetic U46619

BACKGROUND

Estradiol replacement therapy reduces the incidence of coronary artery disease. Current evidence suggests that estradiol may stimulate the production of endothelium-derived NO and thereby reduce the contractile response of vascular smooth muscle. We investigated the effect of long-term replacement of estradiol on NO release and its effect on coronary artery contractility.

METHODS AND RESULTS

Female guinea pigs were ovariectomized and allowed to recover for 100 days. Pellets containing 17 beta-estradiol (0.25, 0.5, 1.5, and 7.5 mg released over 21 days) were placed subcutaneously for 19 to 20 days. Animals were then anesthetized, and the coronary arteries were excised and cut into ring segments. Rings were placed in small-vessel myographs for measurement of isometric force. Contractile responses of coronary arteries to cumulative addition of U46619 (10(-10) to 10(-5) mol/L), a thromboxane mimetic, were measured in the presence and absence of nitro-L-arginine (LNA), a selective NO synthase inhibitor, and methylene blue, a guanylate cyclase inhibitor. Low (0.25-mg) but not high (0.5-, 1.5-, or 7.5-mg) doses of estradiol inhibited the maximal contractile responses to U46619 compared with arteries from untreated castrated animals. In addition, both LNA and methylene blue potentiated contractile responses to U46619 of arteries from animals receiving 0.25 and 0.5 mg but not 1.5 and 7.5 mg estradiol. Negative log EC50 values were significantly inhibited at 0.25 and 7.5 mg but unaffected at 0.5 and 1.5 mg estradiol compared with castrated animals.

CONCLUSIONS

Estradiol at low doses may protect against vasospasm by stimulating endothelium-derived NO release and inhibiting coronary artery contractility.

A placebo-controlled randomized trial of the terbutaline pump for prevention of preterm delivery

To determine the efficacy of the terbutaline pump for the prevention of preterm delivery, patients in preterm labor defined by progressive cervical change underwent intravenous magnesium sulfate tocolysis (with or without oral indomethacin, as necessary), and once labor was arrested, were randomized to one of three treatment arms: terbutaline by pump, saline by pump (blinded), or oral terbutaline. If recurrent preterm labor occurred despite maximization of therapy, the treatment arm was determined and therapy was changed; saline pump and oral terbutaline were switched to terbutaline pump, terbutaline pump was switched to oral terbutaline. Patients who continued to labor were readmitted for aggressive intravenous therapy. Women randomized to the terbutaline pump (n = 15), saline pump (n = 12), and oral terbutaline (n = 15) groups were similar in terms of gravidity, parity, days of tocolysis before study entry, gestational age at entry, and cervical dilatation at entry. The mean gestational age at delivery was the same in all three groups (35 weeks), as were neonatal outcomes. Terbutaline by pump, saline by pump, and oral terbutaline appear equivalent for the prevention of preterm delivery. The terbutaline pump should remain experimental.

Three-dimensional ultrasound in the evaluation of fetal head and spine anomalies

OBJECTIVE

To test the application of three-dimensional (3-D) ultrasound for the antenatal diagnosis of fetal head and spinal anomalies.

METHODS

Twenty-five fetuses with head or spinal anomalies and ranging in gestational age from 16 to 33 weeks were studied prospectively: 11 with a control nervous system anomaly (neural tube defect [n = 4], encephalocele [n = 2], hydrocephalus [n = 4], and anencephaly [n = 1]), 13 fetuses with a family history or suspicion of cleft lip or palate, and one with a cloverleaf skull malformation. A volume scan was performed after the two-dimensional examination was complete. The mechanical transducer scans up to 40 degrees in less than 4 seconds, acquiring the data for a pyramid-shaped tissue volume. Three matched and dynamically linked images representing the X, Y, and Z planes are displayed simultaneously. When one image is manipulated, the remaining images are updated automatically to maintain a 90 degrees difference. After the ideal three orthogonal planes are identified, a 3-D image can be reconstructed. A variable number of scan images are possible, depending on the volume size and the data acquisition time. Processing time for the reconstruction depends on volume size, the number of scan images included, and the degrees of rotation of the final image.

RESULTS

The three orthogonal planes proved most helpful delineating the exact nature and anatomic level of the defect. No examination was delayed or required repetition because of suboptimal fetal positioning. The enhanced confidence achieved by our being able to delineate the precise anatomic level and extent of the defect improved patient counseling. The 3-D reconstructions clarified and documented the true magnitude of the defects and on occasion allowed a diagnosis not possible by either two-dimensional or nonreconstructed 3-D imaging.

CONCLUSION

Our experience with 3-D ultrasound suggests that it is an advance in high-quality ultrasound. Its greatest advantage is that it allows the user to view simultaneously the three orthogonal planes.

Blood transfusion for haemolytic disease as a cause of leukocytosis in the fetus

We evaluated the effect of fetal intravascular transfusion (IVT) of leukocyte-poor red blood cells to correct fetal anaemia due to haemolytic disease on the fetal leukocyte count in 153 patients. Initial, mid-transfusion, and closing haematological studies were obtained when possible. The effect on leukocyte subsets was evaluated by the manual differential count. Fetal leukocyte count increased an average of 18.0 per cent during all IVTs (P < 0.01), despite the dilutional effect of the transfusion. The degree of leukocytosis increased with subsequent transfusions. The smallest (10.1 per cent) change occurred during the initial transfusion. A 41.8 per cent increase was noted during the sixth procedure. There was no relation between leukocytosis and gestational age, volume of transfusion, changes in umbilical vein pressure, or hydrops. Forty-two per cent of the increase was due to expansion of the neutrophil pool and 22 per cent was due to expansion of the monocyte pool. The neutrophil count increased 29 per cent (P < 0.01) and monocytes increased 64.7 per cent (P < 0.001). There was no change in eosinophil and lymphocyte counts. Both an immune aetiology and an effect of inflammatory agents may contribute to this leukocytosis.

Acetylcholine relaxation of renal artery and nitric oxide synthase activity of renal cortex increase with fetal and postnatal age

Endothelium-derived nitric oxide (NO) regulates hemodynamics in the fetal kidney and modulates renal perfusion during postnatal maturation. We hypothesize that NO release by renal arteries increases with fetal maturation and contributes to the increased renal perfusion before and after birth. We tested the effect of maturation on relaxation to acetylcholine (ACh; 10(-9) M to 10(-5) M), the prototypic endothelium-dependent relaxing agent, and sodium nitroprusside (10(-9) M to 10(-5) M), an NO donor, on isolated main renal arteries obtained from anesthetized fetal guinea pigs of varying gestational age (0.5-0.8, 0.8-0.9, and 0.9-0.97 gestation), and neonatal (1-50 d) and reproductively mature adult guinea pigs. The effect of NO synthase inhibition by nitro-L-arginine (LNA; 10(-4) M) and cyclooxygenase inhibition by indomethacin (10(-5) M) on ACh relaxation was also measured. Ca(2+)-dependent NO synthase activity was measured in fetal (0.5-0.87 gestation), neonatal (1-10 d), and adult (mature) renal cortex by the conversion of [L-14C]arginine to [L-14C]citrulline and the time course compared with the relaxation responses. Sensitivity and maximal relaxation to ACh increased with fetal age. In neonatal renal arteries, maximal relaxation but not sensitivity to ACh increased relative to the fetal arteries. In adult renal arteries, both sensitivity and maximal relaxation increased compared with fetal arteries. Sensitivity but not maximal responses to sodium nitroprusside increased with age but exhibited a different maturational pattern than ACh relaxation. LNA inhibited ACh relaxation in arteries of all ages. Indomethacin reduced the sensitivity to ACh only in the fetal arteries. Ca(2+)-dependent NO synthase activity of the renal cortex increased during fetal development reaching levels at near term similar to those found in both the newborn and adult kidneys. These results suggest that endothelium-derived NO release by the renal artery and constitutive NO synthase activity in the renal microvasculature increases with fetal and postnatal maturation. Further, the sensitivity of vascular smooth muscle to NO also increases after birth. Thus, functional adaptations in both the endothelium and the vascular smooth muscle contribute to the maturational changes in mechanisms regulating renal hemodynamics before and after birth.

Diagnostic fetal blood sampling-technique related losses

BACKGROUND

The applications of cordocentesis are limited by its safety. Cordocentesis is performed either freehand or with the aid of a fixed needle guide. Recent reports suggest a loss rate of 1-7% using the freehand technique. The potential influence of technique on the perinatal loss rate has not been examined.

STUDY DESIGN

The procedure-related loss rates of two fetal diagnosis and treatment units, one in the United States (10 operators) and one in Japan (15 operators), who perform diagnostic cordocentesis with the aid of a fixed needle guide is calculated from a prospectively maintained database and compared to the published experience of large centers who use a freehand technique.

RESULTS

A total of 1,260 diagnostic cordocenteses were performed. The mean gestation at sampling was 29.1 +/- 5 weeks. The umbilical vein was punctured in 90%. There were 12 procedure-related losses yielding an overall perinatal loss rate of 0.9%. There was no relationship between the risk of a loss and the number of prior procedures the operator had performed. Losses were more often associated with puncture of the umbilical artery (41.7 vs. 9.2%, p = 0.002). Eleven of 12 losses were associated with a postprocedure bradycardia. Eight fetuses who died had either a trisomy or triploidy, 1 had renal agenesis, 2 had severe early-onset growth restriction and 1 had rhesus disease. For all diagnoses other than a chromosome abnormality and severe fetal growth restriction, the procedure-related loss rate from diagnostic cordocentesis was 0.2% (2/1,021).

CONCLUSION

This study suggests that technique is a variable in the loss rate for cordocentesis.

The ontogeny of cerebral and cerebellar nitric oxide synthase in the guinea pig and rat

The appearance of nitric oxide synthase (NOS, EC 1.14.13.39) activity in the brain of fetal and neonatal guinea pigs and rats was studied. In the guinea pig, NOS increased from an almost undetectable level at 0.49 of gestation (31 d), reaching adult levels before birth and peaking at 140% of the adult activity (forebrain) or 250% of the adult activity (cerebellum) in the week after birth. The rise in fetal NOS activity followed the reported rise in the estrogen receptor concentration in the brain and could be reduced by treatment of the guinea pig at full term with tamoxifen, implicating estrogens in the expression of fetal NOS activity. In the rat, brain NOS activity did not rise significantly until after birth, reaching adult levels approximately 2 wk after birth, and rising to 150 or 130% of the adult activity in the forebrain and cerebellum, respectively, at 4 wk after birth. The appearance of NOS activity in the rat also followed the reported appearance of estrogen receptors in the brain. In both species the appearance of high NOS activity in the brain immediately precedes the period in which maximal synaptogenesis occurs: immediately before birth in the guinea pig and 2-3 wk after birth in the rat. Thus the appearance of a functional estrogen-estrogen receptor system in the brain may be responsible, at least in part, for the expression of a high activity of NOS, which in turn may play important roles in promoting cerebral blood flow and synaptogenesis in the developing brain.

Modern management of Rhesus disease

The cloning of the RhDCcEe complex has made it likely that the polymerase chain reaction will be incorporated into the modern management of rhesus sensitization. Currently, the accuracy of this technique is under evaluation. Its specific role in management protocols is not yet clear. The use of this technology will hopefully avoid the need for cordocentesis or serial amniocenteses in some patients.

Myometrial arginase activity increases with advancing pregnancy in the guinea pig

OBJECTIVES

Arginase has been suggested to play an important role in cellular growth and development, particularly important to the fetus, by supplying L-ornithine for the synthesis of polyamines. The purpose of this investigation was to determine whether pregnancy alters myometrial arginase activity and whether estradiol was responsible for the change.

STUDY DESIGN

Myometrium and kidney were obtained from nonpregnant and pregnant guinea pigs of known gestational age. Arginase activity was measured under physiologic conditions by the conversion carbon 14-labeled guanidino-L-arginine to carbon 14-labeled urea. The concentrations of the enzyme's substrate, L-arginine, and its principal metabolite, L-ornithine, were measured in myometrium from near-term pregnant animals by use of an amino acid analyzer. Finally, a group of random cycle guinea pigs received 500 microgram/kg estradiol for 5 days before the myometrium was removed.

RESULTS

Myometrial arginase activity in pregnant animals was more than double that of myometrium from nonpregnant animals by the time the first measurement was made at 0.14 gestation. It continued to rise, peaking at values >25-fold higher than the nonpregnant activity by 0.90 gestation. Arginase activity in the myometrium underlying the placental implantation site was >25 fold higher (p<0.05) than myometrium from nonpregnant animals when first studied at 0.63 gestation and 10-fold higher than the contralateral fundal myometrium at the same time of gestation. Myometrial arginase activity in the sterile horn of six pregnant animals was half that of the horn containing one or more pups, but still five times higher than that of nonpregnant animals. Renal arginase activity also rose with advancing pregnancy, but the magnitude of the increase (up to 2-fold) was much smaller than that observed in either the fundal or placental implantation site myometrium. Estradiol had no significant effect on myometrial arginase activity.

CONCLUSIONS

These studies demonstrate that pregnancy increases myometrial arginase activity and that the presence of placenta or fetus is necessary for the maximal effect.

Decreased fetal erythropoiesis and hemolysis in Kell hemolytic anemia

OBJECTIVE

Lower changes in optical density (450 nm) measurements have been reported in fetuses with anti-Kell anemia compared with those anti-D anemia. The purpose of this investigation was to determine if hemolysis and erythropoiesis differ between anti-Kell and anti-D hemolytic disease.

STUDY DESIGN

Ninety-three pregnancies complicated by either anti-D or anti-Kell alloimmunization were evaluated. Fetal blood samples obtained at the first cordocentesis were tested for the red blood cell antigen type, hemoglobin, hematocrit, reticulocyte count, nucleated red blood cells, total serum bilirubin concentration, umbilical venous respiratory blood gases, serum erythropoietin level, and strength of the direct Coombs test. To determine the evolution of hemolytic anemia in the two antigen groups, these laboratory parameters were repeated on the fetal blood samples triggering the decision to perform a fetal intravascular transfusion (hematocrit <30%).

RESULTS

A total of 65 of 93 fetuses were antigen positive (11 for Kell and 54 for RhD). The mean gestational age and laboratory measurements of antigen- positive, nonanemic fetuses at first blood sampling did not differ significantly between groups. There was a strong inverse relationship observed between the hemoglobin concentration and reticulocyte count independent of gestational age in the anti-D group but not in the anti-Kell group. Eight (73%) fetuses with anti-Kell antibodies and 37 (69%) with anti-D antibodies underwent intravascular transfusion. At the cordocentesis when the decision for transfusion was made, anti-Kell anemic fetuses had lower reticulocyte counts and total bilirubin concentrations. The strong inverse relationship between the hemoglobin and reticulocyte count was again seen only in the anti-D group. In both groups, fetal erythropoietin increased significantly between the first and last blood samplings and in each group were negatively correlated with hemoglobin independent of gestational age.

CONCLUSION

Anti-Kell anemic fetuses have lower reticulocyte counts and total serum bilirubin levels than do comparable anti-D anemic fetuses. This finding argues in favor of fetal blood sampling rather than amniotic fluid analyses for the management of fetal hemolytic disease resulting from Kell antibodies. Unlike RhD alloimmunized fetuses, these fetuses do not manifest an inverse relationship between hemoglobin concentration and reticulocyte count. We speculate that compared to anti-D fetal anemia, anti-Kell anemia is associated with increased hemolysis of nonhemoglobinized or incompletely hemoglobinized erythroid precursors.

Expression and localization of inducible and endothelial nitric oxide synthase in the rat ovary. Effects of gonadotropin stimulation in vivo

Nitric oxide is reportedly involved in the regulation of several ovarian processes, yet the isoforms of nitric oxide synthase (NOS) expressed in the ovary are unknown. Our purpose was to identify and localize NOS isoenzymes in the rat ovary and to examine++ if mRNA expression of NOS isoenzymes change after gonadotropin stimulation. Using reverse transcriptase-PCR, we demonstrated that inducible (iNOS) and endothelial (eNOS), but not neuronal, NOS mRNAs are expressed in the ovary. In a gonadotropin-stimulated rat model, unstimulated ovaries had the highest levels of iNOS mRNA as quantified by ribonuclease protection assay. After gonadotropin injection, iNOS mRNA declined to undetectable levels in ovaries containing ovulatory follicles before increasing slighty in ovaries containing copora lutea. In situ hybridization studies localized iNOS to granulosa cells of secondary follicles and small antral follicles. Western blots of unstimulated ovaries demonstrated iNOS protein. In contrast to iNOS, eNOS mRNA levels, determined by quantitative PCR, increased after gonadotropin stimulation and peaked in ovaries containing ovulatory follicles before declining in the luteal phase. eNOS protein was localized to blood vessels in the ovary by immunohistochemistry. We conclude that two isoforms of NOS are expressed in the ovary and the mRNA levels for these isozymes are differentially regulated.

Fetal blood sampling and fetal thrombocytopenia

The purpose of this investigation is to determine whether fetal thrombocytopenia is a risk factor for puncture site bleeding. Three groups of fetuses either with or at known risk for thrombocytopenia were identified from a prospectively maintained data base of 1,100 procedures: alloimmune thrombocytopenia (ATP, 29 cordocenteses); unexpected thrombocytopenia (53 cordoncenteses), and intravascular transfusion for fetal hemolytic anemia (194 transfusions). A fourth group (58 cordocenteses) included as a normal control consisted of all appropriately grown fetuses tested within the same gestational age range as those with ATP. In total, 276 fetal blood sampling procedures were included, of which 134 (49%) yielded a platelet count of < 120 x 10(3)/microliters and 38 (14%) a platelet count of < 50 x 10(3)/microliters. The first platelet count obtained from fetuses with ATP ranged from 1 x 10(3) to 159 x 10(3)/microliters. There was no correlation between the platelet count and bleeding time whether the analysis was limited to only pretreatment procedures or included all. Each fetus with unexpected thrombocytopenia was systemically ill. There was no correlation between platelet count and the duration of bleeding from the cord puncture site. Intravascular transfusion produced a significant decline in the platelet count (238 +/- 66 x 10(3) vs. 153 +/- 56 x 10(3)/microliters, p < 0.001). Twenty-nine percent of the post-transfusion platelet counts were below 120 x 10(3)/microliters. There was a significant negative correlation between the final platelet count and the duration of puncture site bleeding (r = -0.178, p = 0.03) independent of either the presence of hydrops, the initial or the increase in the umbilical venous pressure during transfusion.(ABSTRACT TRUNCATED AT 250 WORDS)