The Estimation of Fœtal Maturity by a New Method of X-ray Cephalometry: Its Bearing on Clinical Midwifery: (Section of Obstetrics and Gynæcology)

A plea is made for routine use of X-rays in antenatal work. A new method of cephalometry is described, depending on the fact that the f?tal head is a rough ovoid. It is shown that the shadows cast by ovoids may be oval or circular, but that always the diameter of the greatest circular section of an ovoid is represented in its shadow-by the diameter if the shadow be circular or by the short axis if oval. The results are applied to estimate the actual proportions of f?tal head and maternal pelvis, and also to estimate f?tal maturity.The accuracy of the method of cephalometry was tested in 100 cases of labour induced by rupture of membranes.A simple method of pelvimetry is described, and it is suggested that pelvimetry should be carried out in the early months and not later when the pelvis is obscured.No special apparatus is required and any cottage-hospital X-ray set will serve.     

Role of pelvimetry in active management of labour.

All cases referred for pelvimetry in 1970-1 and all breech presentations referred for pelvimetry in 1972-4 were reviewed. Indications for pelvimetry fell into four main categories: high head in the antenatal clinic (47-8%); high head in labour (13-9%); breech presentation (20-9%); and previous caesarean section (14-8%). In the first two categories pelvimetry rarely if ever influenced management, and it should not be performed routinely. In breech presentation and cases of caesarean section pelvimetry seemed to be of value, but in the latter group it should be performed puerperally to avoid the known radiation hazard to the fetus. A fairly close correlation between obstetric conjugate and pelvic capacity was shown, which suggested that a 3400-g baby might pass through a pelvis of obstetric conjugate of 10 cm as a cephalic trial of labour, but would need an obstetric conjugate of 11-7 cm for safe vaginal breech delivery.     

Vaginal Delivery under Caudal Analgesia after Caesarean Section and other Major Uterine Surgery

In the absence of a recurring indication for caesarean section vaginal delivery in subsequent pregnancy is a “trial of scar,” with potentially serious implications for mother and baby. Labour under caudal analgesia was carefully supervised for 75 women with a surgically scarred uterus—due to lower segment section in 72, abdominal hysterotomy in one, and transcavity myomectomy in two. Every caesarean scar was assessed digitally during labour and every uterus was examined after delivery. Caudal analgesia provided a painless labour and delivery and made scar assessment easy. Controlled intravenous Syntocinon infusion was given to 25 patients. One scar dehiscence occurred early in labour and one in the second stage. Seventy mothers had 71 vaginal deliveries with one pair of twins and one breech. There was one stillbirth and no neonatal death. There were five repeat sections.     

The Long Term Economic Impact of Severe Obstetric Complications for Women and Their Children in Burkina Faso

This study investigates the long term economic impact of severe obstetric complications for women and their children in Burkina Faso, focusing on measures of food security, expenditures and related quality of life measures. It uses a hospital based cohort, first visited in 2004/2005 and followed up four years later. This cohort of 1014 women consisted of two main groups of comparison: 677 women who had an uncomplicated delivery and 337 women who experienced a severe obstetric complication which would have almost certainly caused death had they not received hospital care (labelled a “near miss” event). To analyze the impact of such near miss events as well as the possible interaction with the pregnancy outcome, we compared household and individual level indicators between women without a near miss event and women with a near miss event who either had a live birth, a perinatal death or an early pregnancy loss. We used propensity score matching to remove initial selection bias. Although we found limited effects for the whole group of near miss women, the results indicated negative impacts: a) for near miss women with a live birth, on child development and education, on relatively expensive food consumption and on women’s quality of life; b) for near miss women with perinatal death, on relatively expensive foods consumption and children’s education and c) for near miss women who had an early pregnancy loss, on overall food security. Our results showed that severe obstetric complications have long lasting consequences for different groups of women and their children and highlighted the need for carefully targeted interventions.     

Psychological Antecedents to Conception Among Abortion Seekers

At a university hospital, 642 women seeking induced abortion for an unwanted pregnancy were surveyed before the procedure regarding their perception of what psychological and behavioral factors, if any, played a role in their becoming pregnant: 35 percent said they had had intercourse during what they believed was a “safe period”; 33 percent believed that they had experienced a contraceptive failure; 29 percent indicated fear of side effects influenced their use of a contraceptive method; 27 percent and 21 percent, respectively, indicated that they had thought pregnancy “couldn''t happen to me” or had “put the thought of pregnancy out of my mind.” The women''s responses indicated that a number of additional attitudes, beliefs, and behaviors were also important and that for any individual woman at least three or four factors had often combined in a dynamic sequence to greatly increase her risk of pregnancy. The implications of the findings for educational and counseling programs are discussed.     

Elective Delivery at Term after a Previous Unexplained Intra-Uterine Fetal Death: Audit of Delivery Outcome at Tygerberg Hospital,South Africa

Objectives

To assess the delivery outcome in a pregnancy with a previous unexplained intra-uterine death by elective induction of labour at term.

Methods

An audit of the pregnancy outcome of all women within the catchment area with a current singleton pregnancy; and a previous unexplained or unexplored singleton fetal demise ≥24 weeks (or 500 grams birth weight if gestation unknown) after planned routine induction of labour at full term (39-40 weeks).

Results

During the audit period, 306 patients with a previous intra-uterine fetal death were referred for further management. Of these, 161 had a clear indication for earlier intervention and were excluded from the protocol. Of the remaining 145 patients, 9 met further exclusion criteria and there were 2 patients who defaulted. Forty-two of the remaining study patients (with no known previous medical problems) developed complications during their antenatal course that necessitated a change in clinical management and earlier (<39 weeks) delivery. Of the remaining 92 patients in the audit, 47 (51%) went into spontaneous labour before their induction date; all 92 women delivered without major complications. There were no intra-uterine deaths prior to induction.

Conclusions

Careful follow up at a high risk clinic identifies new or concealed maternal or fetal complications in 29% of patients with a previous intra-uterine death and no obvious maternal or fetal disease in the index pregnancy. When all risks are excluded and the pregnancy allowed to progress to full term (39-40 weeks) before an induction is offered, 50% will go into spontaneous labour.     

Foetal Blood Sampling. Practical Approach to Management of Foetal Distress

The practical application of foetal blood sampling in the routine management of patients in labour has been reviewed in a six-month survey, during which time 1,668 patients were delivered at Queen Charlotte''s Hospital.Foetal acidaemia (pH 7·25 or less) occurred in 45 of the 295 patients who showed clinical signs of foetal distress. Foetal tachycardia was the presenting sign in 33 of these 45 patients, underlining the importance of this physical sign. Foetal acidaemia in association with clinical foetal distress occurred twice as often in patients who had complications of pregnancy and who were therefore regarded as obstetrically “at risk” as it did in patients who were obstetrically “normal” No cases of acidaemia were detected in any of the foetal blood samples performed routinely on “at-risk” patients in the absence of clinical foetal distress.     

Pregnancy Incidence and Correlates in a Clinical Trial Preparedness Study,North West Province South Africa

Introduction

Women in HIV prevention trials often must typically agree to avoid pregnancy. Regardless, some become pregnant. Screening tools predicting pregnancy risk could maximize trial safety and efficiency.

Objectives

We assessed incidence and correlates of pregnancy among women at high HIV risk.

Methods

We enrolled sexually-active, HIV-negative women into an observational cohort (2008–2011). At enrolment demographic, contraceptive, reproductive, pregnancy intention and behavioural data were collected. Women reported if one or both partners wanted or intended for the couple to become pregnant. We measured gender role beliefs using a locally validated eight-point index. We tested HIV and pregnancy, and inquired about sexually transmitted infection symptoms (STIs) at enrollment and monthly. HIV testing included behavioural counselling and condom provision, but did not specifically counsel women to avoid pregnancy. Cox proportional hazard modelling evaluated the associations with pregnancy. The multivariate model included the following variables “Recent pregnancy attempts”, “Gender Roles Beliefs”, ”Self-reported STIs” and “Age”.

Results

We screened 1068 women and excluded (24.6%, 263/1068) who did not report risk behaviour. Non-pregnant, non-sterilized women aged 18–35 (median = 21 years) enrolled (n = 438). Most women reported one partner (74.7%) and a prior live birth (84.6%). Median follow-up time was 6 months (range 0.7–15.5). Pregnancy incidence was 25.1 per 100 women-years (n = 57 pregnancies). Conservative beliefs on gender roles (Adjusted Hazard Ratio (aHR) 1.8; 95% confidence interval [CI] 1.1–2.9), recent pregnancy attempts (aHR 1.9; 95% CI 1.1–3.4) and baseline self-reported STI (aHR 2.5; 95% CI 1.4–4.4) were associated with increased incident pregnancy. Report of no pregnancy intention was associated with lowered pregnancy risk (aHR 0.3; 95% CI 0.1–0.7).

Conclusions

We identified new and confirmed existing factors that can facilitate screening for pregnancy risk.     

Development and validation of a risk prediction model of preterm birth for women with preterm labour symptoms (the QUIDS study): A prospective cohort study and individual participant data meta-analysis

BackgroundTimely interventions in women presenting with preterm labour can substantially improve health outcomes for preterm babies. However, establishing such a diagnosis is very challenging, as signs and symptoms of preterm labour are common and can be nonspecific. We aimed to develop and externally validate a risk prediction model using concentration of vaginal fluid fetal fibronectin (quantitative fFN), in combination with clinical risk factors, for the prediction of spontaneous preterm birth and assessed its cost-effectiveness.Methods and findingsPregnant women included in the analyses were 22⁺⁰ to 34⁺⁶ weeks gestation with signs and symptoms of preterm labour. The primary outcome was spontaneous preterm birth within 7 days of quantitative fFN test. The risk prediction model was developed and internally validated in an individual participant data (IPD) meta-analysis of 5 European prospective cohort studies (2009 to 2016; 1,783 women; mean age 29.7 years; median BMI 24.8 kg/m²; 67.6% White; 11.7% smokers; 51.8% nulliparous; 10.4% with multiple pregnancy; 139 [7.8%] with spontaneous preterm birth within 7 days). The model was then externally validated in a prospective cohort study in 26 United Kingdom centres (2016 to 2018; 2,924 women; mean age 28.2 years; median BMI 25.4 kg/m²; 88.2% White; 21% smokers; 35.2% nulliparous; 3.5% with multiple pregnancy; 85 [2.9%] with spontaneous preterm birth within 7 days). The developed risk prediction model for spontaneous preterm birth within 7 days included quantitative fFN, current smoking, not White ethnicity, nulliparity, and multiple pregnancy. After internal validation, the optimism adjusted area under the curve was 0.89 (95% CI 0.86 to 0.92), and the optimism adjusted Nagelkerke R² was 35% (95% CI 33% to 37%). On external validation in the prospective UK cohort population, the area under the curve was 0.89 (95% CI 0.84 to 0.94), and Nagelkerke R² of 36% (95% CI: 34% to 38%). Recalibration of the model’s intercept was required to ensure overall calibration-in-the-large. A calibration curve suggested close agreement between predicted and observed risks in the range of predictions 0% to 10%, but some miscalibration (underprediction) at higher risks (slope 1.24 (95% CI 1.23 to 1.26)). Despite any miscalibration, the net benefit of the model was higher than “treat all” or “treat none” strategies for thresholds up to about 15% risk. The economic analysis found the prognostic model was cost effective, compared to using qualitative fFN, at a threshold for hospital admission and treatment of ≥2% risk of preterm birth within 7 days. Study limitations include the limited number of participants who are not White and levels of missing data for certain variables in the development dataset.ConclusionsIn this study, we found that a risk prediction model including vaginal fFN concentration and clinical risk factors showed promising performance in the prediction of spontaneous preterm birth within 7 days of test and has potential to inform management decisions for women with threatened preterm labour. Further evaluation of the risk prediction model in clinical practice is required to determine whether the risk prediction model improves clinical outcomes if used in practice.Trial registrationThe study was approved by the West of Scotland Research Ethics Committee (16/WS/0068). The study was registered with ISRCTN Registry (ISRCTN 41598423) and NIHR Portfolio (CPMS: 31277).

Sarah J Stock and colleagues develop and validate a risk prediction model of spontaneous preterm birth for women with preterm labour symptoms, based on vaginal fluid fetal fibronectin and clinical risk factors.     

Familial Trends in Low Birth Weight

The reproductive performance of sisters and sisters-in-law of 185 women who had delivered “light-for-dates” and “premature expulsion” low birth weight infants was studied. Percentile birth weights were compared taking into account length of gestation, fetal sex, and the height, weight, parity, and smoking habits of the mother. Sisters of women who had delivered light-for-dates babies had lighter babies than the general population, their sisters-in-law, or the sisters of women in the premature expulsion group. These other groups, however, had the expected distribution of percentile birth weights. Data on familial trends in smoking habits and unknown gestation are also presented. The results are consistent with the theory that the mother''s own intrauterine experience affects her reproductive performance but could also be explained by shared family learning experience of as yet unidentified microsocial factors related to pregnancy performance.     

Women’s Longitudinal Patterns of Smoking during the Pre-Conception,Pregnancy and Postnatal Period: Evidence from the UK Infant Feeding Survey

BackgroundAn understanding of women’s longitudinal patterns of smoking during the pre-conception, pregnancy and postnatal period and the factors associated with these patterns could help better inform smoking cessation services and interventions.MethodsLatent class analysis (LCA) was used to empirically identify women’s smoking patterns in a sample of 10,768 mothers from the 2010 UK Infant Feeding Survey. Multinomial logistic regression was used to identify characteristics associated with these patterns.ResultsLCA identified five distinct smoking patterns during the pre-conception, pregnancy and postnatal period: “non-smokers” (74.1% of women); “pregnancy-inspired quitters” (10.2%); “persistent smokers” (10.1%); “temporary quitters” (4.4%); and postnatal quitters (1.1%). Smoking patterns varied markedly according to socio-demographic variables and parity. After adjusting for these variables, mothers who lived during pregnancy with a partner who smoked were more likely to be temporary quitters (aOR 2.64, 95% CI 1.74–3.99) or persistent smokers (aOR 3.32, 95% CI 2.34–4.72) than pregnancy-inspired quitters. Mothers who lived during pregnancy with someone else other than a partner who smoked were more likely to be persistent smokers (aOR 2.34, 95% CI 1.38–3.97) or postnatal quitters (aOR 2.97, 95% CI 1.07–8.24) than pregnancy-inspired quitters. Mothers given information on how their partner could stop smoking if they lived during pregnancy with a smoking partner were less likely to be persistent smokers (aOR 0.42, 95% CI 0.27–0.65) than pregnancy-inspired quitters.ConclusionHealth professionals should ask about smoking at every opportunity, and refer women who self-report as current smokers to an evidence based smoking cessation service.     

Clinical Utility of Antithrombotic Prophylaxis in ART Procedures: An Italian Experience

Background

The usefulness of antithrombotic prophylaxis in management of Assisted Reproductive Technologies (ART) is questionable.

Objectives

We prospectively examined the contribution of an antithrombotic prophylaxis in influencing clinical pregnancy and live-birth in an unselected cohort of women approaching ART.

Patients/Methods

1107 women with fertility problems and a valid indication for ART were recruited. Baseline and follow-up information of obstetric outcomes and antithrombotic treatment were collected.

Results and Conclusions

Median follow-up time was 34.5 months (range: 2–143). During the follow-up period, 595 (53.8%) women underwent ART (total 1234 cycles); 202 (33.9%) women achieved a pregnancy for a total of 255 clinical pregnancies. The concomitant use of LMWH and aspirin was significantly associated with a higher rate of clinical pregnancies (p: 0.003, OR: 4.9, 95% CI: 1.7–14.2). The pregnancy rate was also significantly increased by the use of LMWH alone (p: 0.005, OR: 2.6, 95% CI: 1.3–5.0). Carriership of inherited or acquired thrombophilia did not affect clinical outcomes of the ART. The efficacy of antithrombotic treatment was confirmed when the outcome “ live-birth” was considered. Present data suggest a potential benefit of antithrombotic prophylaxis during ART in improving the number of live-births.     

Mothers' experiences of induction

Mothers of a random sample of 2182 legitimate live births were interviewed about their experiences of pregnancy, labour, and delivery. Of these, 24% reported that their labours were induced, and data about this from a subsample of mothers tallied with information obtained through the doctors in charge in 88% of cases. All but 3% of the mothers who were induced perceived some medical reason for the induction. The proportion of inductions in the 24 study areas ranged from 6% to 39%. A relatively small proportion of labours in “teaching” hospitals, small hospitals with less than 100 beds, and GP maternity hospitals were induced, but a comparatively high proportion of private patients had an induction. There was no clear association between induction and the mother''s age or parity. Despite being given more pain relief, those who were induced reported similar intensities of pain during the first and second stages of labour to those whose labour started spontaneously; they also reported that they had “bad pains” for a similar period. The period they had contractions was shorter for the induced than for those starting spontaneously, and the intensity of pain at delivery was rated somewhat less by those who were induced.There was no difference between induced babies and others in the proportion who were held by their mothers immediately after their birth. Two-fifths of the mothers who were induced would have liked more information about induction; and a similar proportion said they had not discussed induction with a doctor, midwife, or nurse during their pregnancy. Only 17% of the mothers who had an induction said they would prefer to be induced if they had another baby. This contrasts with 63% of those who had epidural analgesia who would opt for the same procedure next time, while 83% of those who had had a baby in hospital, and 91% of those having had a home birth, would want their next baby in the same type of place.     

Statistical Analysis of Individual Participant Data Meta-Analyses: A Comparison of Methods and Recommendations for Practice

Background

Individual participant data (IPD) meta-analyses that obtain “raw” data from studies rather than summary data typically adopt a “two-stage” approach to analysis whereby IPD within trials generate summary measures, which are combined using standard meta-analytical methods. Recently, a range of “one-stage” approaches which combine all individual participant data in a single meta-analysis have been suggested as providing a more powerful and flexible approach. However, they are more complex to implement and require statistical support. This study uses a dataset to compare “two-stage” and “one-stage” models of varying complexity, to ascertain whether results obtained from the approaches differ in a clinically meaningful way.

Methods and Findings

We included data from 24 randomised controlled trials, evaluating antiplatelet agents, for the prevention of pre-eclampsia in pregnancy. We performed two-stage and one-stage IPD meta-analyses to estimate overall treatment effect and to explore potential treatment interactions whereby particular types of women and their babies might benefit differentially from receiving antiplatelets. Two-stage and one-stage approaches gave similar results, showing a benefit of using anti-platelets (Relative risk 0.90, 95% CI 0.84 to 0.97). Neither approach suggested that any particular type of women benefited more or less from antiplatelets. There were no material differences in results between different types of one-stage model.

Conclusions

For these data, two-stage and one-stage approaches to analysis produce similar results. Although one-stage models offer a flexible environment for exploring model structure and are useful where across study patterns relating to types of participant, intervention and outcome mask similar relationships within trials, the additional insights provided by their usage may not outweigh the costs of statistical support for routine application in syntheses of randomised controlled trials. Researchers considering undertaking an IPD meta-analysis should not necessarily be deterred by a perceived need for sophisticated statistical methods when combining information from large randomised trials.     

Interaction between Maternal Passive Smoking during Pregnancy and CYP1A1 and GSTs Polymorphisms on Spontaneous Preterm Delivery

Objective

The present study aimed to examine the association between maternal passive smoking during pregnancy and the risk of spontaneous PTD and to explore the potential interaction of the single or joint gene polymorphism of CYP1A1 and GSTs with maternal passive smoking on the risk of spontaneous PTD.

Method

We investigated whether the association between maternal passive smoking and PTD can be modified by 2 metabolic genes, i.e. cytochrome P4501A1 (CYP1A1) and glutathione S-transferases (GSTs), in a case-control study with 198 spontaneous preterm and 524 term deliveries in Shenzhen and Foshan, China. We used logistic regression to test gene-passive smoking interaction, adjusting for maternal socio-demographics and prepregnancy body mass index.

Results

Overall, maternal passive smoking during pregnancy was associated with higher risk of PTD (adjusted odds ratio = 2.20 [95% confidence interval: 1.56–3.12]). This association was modified by CYP1A1 and GSTs together, but not by any single genotype. For cross-categories of CYP1A1 Msp I and GSTs, maternal passive smoking was associated with higher risk of PTD among those women with CYP1A1 “TC/CC”+ GSTs “null”, but not among women with other genotypes; and this interaction was significant (OR = 2.66 [95% CI: 1.19–5.97]; P-value: 0.017). For cross-categories of CYP1A1 BsrD I and GSTs, maternal passive smoking was associated with higher risk of PTD only among those women with CYP1A1“AG/GG”+ GSTs “null”, but not among women with other genotypes; and this interaction was significant (OR = 3.00 [95% CI: 1.17–7.74]; P-value: 0.023).

Conclusions

Our findings suggest that the combined genotypes of CYP1A1 and GSTs can help to identify vulnerable pregnant women who are subject to high risk of spontaneous PTD due to passive smoking.     

Outcome of planned home births in an inner city practice.

OBJECTIVE--To assess the outcome of pregnancy for women booking for home births in an inner London practice between 1977 and 1989. DESIGN--Retrospective review of practice obstetric records. SETTING--A general practice in London. SUBJECTS--285 women registered with the practice or referred by neighbouring general practitioners or local community midwives. MAIN OUTCOME MEASURES--Place of birth and number of cases transferred to specialist care before, during, and after labour. RESULTS--Of 285 women who booked for home births, eight left the practice area before the onset of labour, giving a study population of 277 women. Six had spontaneous abortions, 26 were transferred to specialist care during pregnancy, another 26 were transferred during labour, and four were transferred in the postpartum period. 215 women (77.6%, 95% confidence interval 72.7 to 82.5) had normal births at home without needing specialist help. Transfer to specialist care during pregnancy was not significantly related to parity, but nulliparous women were significantly more likely to require transfer during labour (p = 0.00002). Postnatal complications requiring specialist attention were uncommon among mothers delivered at home (four cases) and rare among their babies (three cases). CONCLUSIONS--Birth at home is practical and safe for a self selected population of multiparous women, but nulliparous women are more likely to require transfer to hospital during labour because of delay in labour. Close cooperation between the general practitioner and both community midwives and hospital obstetricians is important in minimising the risks of trial of labour at home.     

Ectopic Pregnancy: A Review of 113 Selected Cases

One hundred and thirteen selected cases of ectopic pregnancy were analyzed to clarify the diagnostic and therapeutic factors. The incidence of this condition was higher in “ward” patients and in the Negro. Salpingitis was the commonest etiological factor. The common symptoms were pain, a missed period, vaginal bleeding, faintness, nausea and vomiting, and shoulder pain. The common signs were abdominal tenderness, a positive “chandelier sign”, rebound tenderness, a pelvic mass and pallor. Fertility of the women in this series was equal to that of women in the general population of the same age group. The frog (pregnancy) test was the only significant laboratory test. Colpocentesis proved very helpful, whereas dilatation and curettage did not. Conservative operation, consisting of salpingectomy plus a uterine wedge, was recommended for tubal pregnancy and was performed in 107 patients. The ovary was removed only if involved. Interstitial pregnancies were treated by removal of the corneal portion of the uterus and by salpingectomy, rather than hysterectomy; this procedure was successful in four out of four patients. Incidental appendectomy is not recommended.     

Reduction of Pavlovian Bias in Schizophrenia: Enhanced Effects in Clozapine-Administered Patients

The negative symptoms of schizophrenia (SZ) are associated with a pattern of reinforcement learning (RL) deficits likely related to degraded representations of reward values. However, the RL tasks used to date have required active responses to both reward and punishing stimuli. Pavlovian biases have been shown to affect performance on these tasks through invigoration of action to reward and inhibition of action to punishment, and may be partially responsible for the effects found in patients. Forty-five patients with schizophrenia and 30 demographically-matched controls completed a four-stimulus reinforcement learning task that crossed action (“Go” or “NoGo”) and the valence of the optimal outcome (reward or punishment-avoidance), such that all combinations of action and outcome valence were tested. Behaviour was modelled using a six-parameter RL model and EEG was simultaneously recorded. Patients demonstrated a reduction in Pavlovian performance bias that was evident in a reduced Go bias across the full group. In a subset of patients administered clozapine, the reduction in Pavlovian bias was enhanced. The reduction in Pavlovian bias in SZ patients was accompanied by feedback processing differences at the time of the P3a component. The reduced Pavlovian bias in patients is suggested to be due to reduced fidelity in the communication between striatal regions and frontal cortex. It may also partially account for previous findings of poorer “Go-learning” in schizophrenia where “Go” responses or Pavlovian consistent responses are required for optimal performance. An attenuated P3a component dynamic in patients is consistent with a view that deficits in operant learning are due to impairments in adaptively using feedback to update representations of stimulus value.     

Structural transition produced by electric fields in aqueous sodium deoxyribonucleate

It was found that the birefringence of aqueous solutions of sodium DNA is anomalous when electric fields of high intensity (≥10⁴ v/cm) are applied. The magnitude of the birefringence first rose upon application of the orienting pulse, then fell as the field was sustained above a critical value. The occurrence of the effect depended upon macromolecular and electrolyte concentrations. Upon removal of the field, the birefringence was rapidly restored and then it decayed with an increase of the reorientational relaxation times, relative to those observed below the critical field. It is proposed that the electric field may cause aggregation of the macromolecules and then produce a structural transition concomitant with the electric field orientation effect. This transition may correspond to the “B” “A” structures identified in x-ray studies, or to a “B” “V” structure change, where “V” is a postulated new helical form stabilized by cooperative interactions of base and dipoles in the electric field. Field induced transitions of this type would be of interest in connection with molecular mechanisms of transport through membranes, nerve impulse transmission, or information storage.